Effects of metallic nanoparticle doped flux on the interfacial intermetallic compounds between lead-free solder ball and copper substrate

Energy Technology Data Exchange (ETDEWEB)

Sujan, G.K., E-mail: sgkumer@gmail.com; Haseeb, A.S.M.A., E-mail: haseeb@um.edu.my; Afifi, A.B.M., E-mail: amalina@um.edu.my

2014-11-15

of flux with appropriate metallic nanoparticles can be successfully used to control the morphology and growth of intermetallic compound layers at the solder/substrate interface which is expected to lead to better reliability of electronic devices. - Highlights: • A novel nanodoped flux method has been developed to control the growth of IMCs. • Ni doped flux improves the wettability, but Co, Mo and Ti deteriorate it. • Ni and Co doped flux gives planer IMC morphology through in-situ alloying effect. • 0.1 wt.% Ni and Co addition into flux gives the lowest interfacial IMC thickness. • Mo and Ti doped flux does not have any influence at the interfacial reaction.

Role of intermetallics on the mechanical fatigue behavior of Cu–Al ball bond interfaces

Energy Technology Data Exchange (ETDEWEB)

Lassnig, A., E-mail: alice.lassnig@univie.ac.at [University of Vienna, Faculty of Physics, Physics of Nanostructured Materials, Boltzmanngasse 5, 1090 Wien (Austria); Pelzer, R. [Infineon Technologies Austria AG, Siemensstrae 2, 9500 Villach (Austria); Gammer, C. [University of Vienna, Faculty of Physics, Physics of Nanostructured Materials, Boltzmanngasse 5, 1090 Wien (Austria); National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Khatibi, G. [Vienna University of Technology, Institute of Chemical Technology and Analytics, Getreidemarkt 9, 1060 Wien (Austria)

2015-10-15

The mechanical fatigue behavior of Cu–Al interfaces occurring in thermosonic ball bonds –typically used in microelectronic packages for automotive applications – is investigated by means of a specially designed fatigue test technique. Fully reversed cyclic shear stresses are induced at the bond interface, leading to subsequent fatigue lift off failure and revealing the weakest site of the bond. A special focus is set on the role of interfacial intermetallic compounds (IMC) on the fatigue performance of such interfaces. Therefore fatigue life curves were obtained for three representative microstructural states: The as-bonded state is compared to two annealed states at 200 °C for 200 h and at 200 °C for 2000 h respectively. In the moderately annealed state two IMC layers (Al{sub 2}Cu, Al{sub 4}Cu{sub 9}) could be identified, whereas in the highly aged state the original pad metallization was almost entirely consumed and AlCu is formed as a third IMC. Finally, the crack path is traced back as a function of interfacial microstructure by means of electron microscopy techniques. Whereas conventional static shear tests reveal no significant decrease of the bond shear force with increased IMC formation the fatigue tests prove a clear degradation in the cyclic mechanical performance. It can be concluded that during cycling the crack deflects easily into the formed intermetallics, leading to early failure of the ball bonds due to their brittle nature. - Highlights: • High cycle fatigue of various miniaturized Cu–Al interfaces is investigated. • Interfacial intermetallic compounds consist of Al2Cu, AlCu and Al4Cu9. • Static shear strength shows minor dependency on interfacial phase formation. • Fatigue tests prove significant degradation with intermetallic compound evolution. • Fatigue fracture surface analysis reveal microstructure dependent crack path.

Role of intermetallics on the mechanical fatigue behavior of Cu–Al ball bond interfaces

International Nuclear Information System (INIS)

Lassnig, A.; Pelzer, R.; Gammer, C.; Khatibi, G.

2015-01-01

The mechanical fatigue behavior of Cu–Al interfaces occurring in thermosonic ball bonds –typically used in microelectronic packages for automotive applications – is investigated by means of a specially designed fatigue test technique. Fully reversed cyclic shear stresses are induced at the bond interface, leading to subsequent fatigue lift off failure and revealing the weakest site of the bond. A special focus is set on the role of interfacial intermetallic compounds (IMC) on the fatigue performance of such interfaces. Therefore fatigue life curves were obtained for three representative microstructural states: The as-bonded state is compared to two annealed states at 200 °C for 200 h and at 200 °C for 2000 h respectively. In the moderately annealed state two IMC layers (Al 2 Cu, Al 4 Cu 9 ) could be identified, whereas in the highly aged state the original pad metallization was almost entirely consumed and AlCu is formed as a third IMC. Finally, the crack path is traced back as a function of interfacial microstructure by means of electron microscopy techniques. Whereas conventional static shear tests reveal no significant decrease of the bond shear force with increased IMC formation the fatigue tests prove a clear degradation in the cyclic mechanical performance. It can be concluded that during cycling the crack deflects easily into the formed intermetallics, leading to early failure of the ball bonds due to their brittle nature. - Highlights: • High cycle fatigue of various miniaturized Cu–Al interfaces is investigated. • Interfacial intermetallic compounds consist of Al2Cu, AlCu and Al4Cu9. • Static shear strength shows minor dependency on interfacial phase formation. • Fatigue tests prove significant degradation with intermetallic compound evolution. • Fatigue fracture surface analysis reveal microstructure dependent crack path

Massive spalling of Cu-Zn and Cu-Al intermetallic compounds at the interface between solders and Cu substrate during liquid state reaction

Science.gov (United States)

Kotadia, H. R.; Panneerselvam, A.; Mokhtari, O.; Green, M. A.; Mannan, S. H.

2012-04-01

The interfacial intermetallic compound (IMC) formation between Cu substrate and Sn-3.8Ag-0.7Cu-X (wt.%) solder alloys has been studied, where X consists of 0-5% Zn or 0-2% Al. The study has focused on the effect of solder volume as well as the Zn or Al concentration. With low solder volume, when the Zn and Al concentrations in the solder are also low, the initial Cu-Zn and Al-Cu IMC layers, which form at the solder/substrate interface, are not stable and spall off, displaced by a Cu6Sn5 IMC layer. As the total Zn or Al content in the system increases by increasing solder volume, stable CuZn or Al2Cu IMCs form on the substrate and are not displaced. Increasing concentration of Zn has a similar effect of stabilizing the Cu-Zn IMC layer and also of forming a stable Cu5Zn8 layer, but increasing Al concentration alone does not prevent spalling of Al2Cu. These results are explained using a combination of thermodynamic- and kinetics-based arguments.

Void formation and its impact on Cu−Sn intermetallic compound formation

International Nuclear Information System (INIS)

Ross, Glenn; Vuorinen, Vesa; Paulasto-Kröckel, Mervi

2016-01-01

Void formation in the Cu−Sn system has been identified as a major reliability issue with small volume electronic interconnects. Voids form during the interdiffusion of electrochemically deposited Cu and Sn, with varying magnitude and density. Electroplating parameters include the electrolytic chemistry composition and the electroplating current density, all of which appear to effect the voiding characteristics of the Cu−Sn system. In addition, interfacial voiding affects the growth kinetics of the Cu_3Sn and Cu_6Sn_5 intermetallic compounds of the Cu−Sn system. The aim here is to present voiding data as a function of electroplating chemistry and current density over a duration (up to 72 h) of isothermal annealing at 423 K (150 °C). Voiding data includes the average interfacial void size and average void density. Voids sizes grew proportionally as a function of thermal annealing time, whereas the void density grew initially very quickly but tended to saturate at a fixed density. A morphological evolution analysis called the physicochemical approach is utilised to understand the processes that occur when a voided Cu/Cu_3Sn interface causes changes to the IMC phase growth. The method is used to simulate the intermetallic thickness growths' response to interfacial voiding. The Cu/Cu_3Sn interface acts as a Cu diffusion barrier disrupting the diffusion of Cu. This resulted in a reduction in the Cu_3Sn thickness and an accelerated growth rate of Cu_6Sn_5. - Highlights: • Average void size is proportional linearly to thermal annealing time. • Average void density grows initially very rapidly followed by saturation. • Voids located close to the Cu/Cu_3Sn interface affect IMC growth rates. • Voids act as a diffusion barrier inhibiting Cu diffusion towards Sn. • Voids located at the interface cause Cu_3Sn to be consumed by Cu_6Sn_5.

Microstructure and tribological properties of Ti–Cu intermetallic compound coating

International Nuclear Information System (INIS)

Guo, Chun; Zhou, Jiansong; Yu, Youjun; Wang, Lingqian; Zhou, Huidi; Chen, Jianmin

2012-01-01

Highlights: ► Ti–Cu coating has been synthesized on pure Ti substrate by laser cladding. ► Microstructure and tribological properties of Ti–Cu coating were analyzed. ► The prepared Ti–Cu intermetallic compound coating has excellent wear resistance. -- Abstract: Ti–Cu intermetallic compound coating has been in situ synthesized successfully on pure Ti substrate by laser cladding using copper powder as the precursor. It has been found that the prepared coating mainly contains of TiCu, TiCu 3 , Ti 3 Cu, and Ti phases. The transmission electron microscopy results conform further the existence of Ti–Cu intermetallic compound in the fabricated coating. Tribological properties of the prepared Ti–Cu intermetallic compound coating were systematically evaluated. It was found that normal loads and sliding speeds have a strong influence on the friction coefficient and wear rate of Ti–Cu intermetallic compound coating. Namely, the friction coefficient of the Ti–Cu intermetallic compound coating decreased with increasing normal load and sliding speed. The wear rate of the Ti–Cu intermetallic compound coating decreased rapidly with increasing sliding speed, while the wear rate increased as the normal load increased.

Rare earth intermetallic compounds produced by a reduction-diffusion process

International Nuclear Information System (INIS)

Cech, R.E.

1975-01-01

A reduction-diffusion process is given for producing novel rare earth intermetallic compounds, such as cobalt--rare earth intermetallic compounds, especially compounds useful in preparing permanent magnets. A particulate mixture of rare earth metal halide, cobalt and calcium hydride is heated to effect reduction of the rare earth metal halide and to diffuse the resulting rare earth metal into the cobalt to form the intermetallic compound

Microstructure and tribological properties of TiAg intermetallic compound coating

International Nuclear Information System (INIS)

Guo Chun; Chen Jianmin; Zhou Jiansong; Zhao Jierong; Wang Linqian; Yu Youjun; Zhou Huidi

2011-01-01

TiAg intermetallic compound coating has been in situ synthesized successfully on pure Ti substrate by laser cladding using Ag powder as the precursor. It has been found that the prepared coating mainly comprised TiAg and Ti phases. The high resolution transmission electron microscopy results further conform the existence of TiAg intermetallic compound in the prepared coating. The magnified high resolution transmission electron microscopy images shown that the laser cladding coating contains TiAg nanocrystalline with the size of about 4 nm. Tribological properties of the prepared TiAg intermetallic compound coating were systematically evaluated. It was found that the friction coefficient and wear rate was closely related to the normal load and sliding speed, i.e., the friction coefficient of the prepared TiAg intermetallic compound coating decreased with increasing normal load and sliding speed. The wear rate of the TiAg intermetallic compound coating decreased rapidly with increasing sliding speed, while the wear rate increased as the normal load increased.

Microstructure and tribological properties of TiAg intermetallic compound coating

Energy Technology Data Exchange (ETDEWEB)

Guo Chun [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Graduate University of Chinese Academy of Sciences, Beijing 100039 (China); Chen Jianmin, E-mail: chenjm@lzb.ac.cn [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Zhou Jiansong [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Zhao Jierong; Wang Linqian; Yu Youjun [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Graduate University of Chinese Academy of Sciences, Beijing 100039 (China); Zhou Huidi [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

2011-10-01

TiAg intermetallic compound coating has been in situ synthesized successfully on pure Ti substrate by laser cladding using Ag powder as the precursor. It has been found that the prepared coating mainly comprised TiAg and Ti phases. The high resolution transmission electron microscopy results further conform the existence of TiAg intermetallic compound in the prepared coating. The magnified high resolution transmission electron microscopy images shown that the laser cladding coating contains TiAg nanocrystalline with the size of about 4 nm. Tribological properties of the prepared TiAg intermetallic compound coating were systematically evaluated. It was found that the friction coefficient and wear rate was closely related to the normal load and sliding speed, i.e., the friction coefficient of the prepared TiAg intermetallic compound coating decreased with increasing normal load and sliding speed. The wear rate of the TiAg intermetallic compound coating decreased rapidly with increasing sliding speed, while the wear rate increased as the normal load increased.

Void formation and its impact on Cu−Sn intermetallic compound formation

Energy Technology Data Exchange (ETDEWEB)

Ross, Glenn, E-mail: Glenn.Ross@aalto.fi; Vuorinen, Vesa; Paulasto-Kröckel, Mervi

2016-08-25

Void formation in the Cu−Sn system has been identified as a major reliability issue with small volume electronic interconnects. Voids form during the interdiffusion of electrochemically deposited Cu and Sn, with varying magnitude and density. Electroplating parameters include the electrolytic chemistry composition and the electroplating current density, all of which appear to effect the voiding characteristics of the Cu−Sn system. In addition, interfacial voiding affects the growth kinetics of the Cu{sub 3}Sn and Cu{sub 6}Sn{sub 5} intermetallic compounds of the Cu−Sn system. The aim here is to present voiding data as a function of electroplating chemistry and current density over a duration (up to 72 h) of isothermal annealing at 423 K (150 °C). Voiding data includes the average interfacial void size and average void density. Voids sizes grew proportionally as a function of thermal annealing time, whereas the void density grew initially very quickly but tended to saturate at a fixed density. A morphological evolution analysis called the physicochemical approach is utilised to understand the processes that occur when a voided Cu/Cu{sub 3}Sn interface causes changes to the IMC phase growth. The method is used to simulate the intermetallic thickness growths' response to interfacial voiding. The Cu/Cu{sub 3}Sn interface acts as a Cu diffusion barrier disrupting the diffusion of Cu. This resulted in a reduction in the Cu{sub 3}Sn thickness and an accelerated growth rate of Cu{sub 6}Sn{sub 5}. - Highlights: • Average void size is proportional linearly to thermal annealing time. • Average void density grows initially very rapidly followed by saturation. • Voids located close to the Cu/Cu{sub 3}Sn interface affect IMC growth rates. • Voids act as a diffusion barrier inhibiting Cu diffusion towards Sn. • Voids located at the interface cause Cu{sub 3}Sn to be consumed by Cu{sub 6}Sn{sub 5}.

Effects of Metallic Nanoparticles on Interfacial Intermetallic Compounds in Tin-Based Solders for Microelectronic Packaging

Science.gov (United States)

Haseeb, A. S. M. A.; Arafat, M. M.; Tay, S. L.; Leong, Y. M.

2017-10-01

Tin (Sn)-based solders have established themselves as the main alternative to the traditional lead (Pb)-based solders in many applications. However, the reliability of the Sn-based solders continues to be a concern. In order to make Sn-based solders microstructurally more stable and hence more reliable, researchers are showing great interest in investigating the effects of the incorporation of different nanoparticles into them. This paper gives an overview of the influence of metallic nanoparticles on the characteristics of interfacial intermetallic compounds (IMCs) in Sn-based solder joints on copper substrates during reflow and thermal aging. Nanocomposite solders were prepared by mechanically blending nanoparticles of nickel (Ni), cobalt (Co), zinc (Zn), molybdenum (Mo), manganese (Mn) and titanium (Ti) with Sn-3.8Ag-0.7Cu and Sn-3.5Ag solder pastes. The composite solders were then reflowed and their wetting characteristics and interfacial microstructural evolution were investigated. Through the paste mixing route, Ni, Co, Zn and Mo nanoparticles alter the morphology and thickness of the IMCs in beneficial ways for the performance of solder joints. The thickness of Cu3Sn IMC is decreased with the addition of Ni, Co and Zn nanoparticles. The thickness of total IMC layer is decreased with the addition of Zn and Mo nanoparticles in the solder. The metallic nanoparticles can be divided into two groups. Ni, Co, and Zn nanoparticles undergo reactive dissolution during solder reflow, causing in situ alloying and therefore offering an alternative route of alloy additions to solders. Mo nanoparticles remain intact during reflow and impart their influence as discrete particles. Mechanisms of interactions between different types of metallic nanoparticles and solder are discussed.

Concurrent nucleation, formation and growth of two intermetallic compounds (Cu6Sn5 and Cu3Sn) during the early stages of lead-free soldering

International Nuclear Information System (INIS)

Park, M.S.; Arróyave, R.

2012-01-01

This study investigates the concurrent nucleation, formation and growth of two intermetallic compounds (IMCs), Cu 6 Sn 5 (η) and Cu 3 Sn (ε), during the early stages of soldering in the Cu–Sn system. The nucleation, formation and growth of the IMC layers is simulated through a multiphase-field model in which the concurrent nucleation of both IMC phases is considered to be a stochastic Poisson process with nucleation rates calculated from classical nucleation theory. CALPHAD thermodynamic models are used to calculate the local contributions to the free energy of the system and the driving forces for precipitation of the IMC phases. The nucleation parameters of the η phase are estimated from experimental results and those of the ε phase are assumed to be similar. A parametric investigation of the effects of model parameters (e.g. grain boundary (GB) diffusion rates, interfacial and GB energies) on morphological evolution and IMC layer growth rate is presented and compared with previous works in which nucleation was ignored . In addition, the resulting growth rates are compared with the available literature and it is found that, for a certain range in the model parameters, the agreement is quite satisfactory. This work provides valuable insight into the dominant mechanisms for mass transport as well as morphological evolution and growth of IMC layers during early stages of Pb-free soldering.

Microstructure and tribological properties of TiCu2Al intermetallic compound coating

International Nuclear Information System (INIS)

Guo Chun; Zhou Jiansong; Zhao Jierong; Wang Linqian; Yu Youjun; Chen Jianmin; Zhou Huidi

2011-01-01

TiCu 2 Al ternary intermetallic compound coating has been in situ synthesized successfully on pure Ti substrate by laser cladding. Tribological properties of the prepared TiCu 2 Al intermetallic compound coating were systematically evaluated. It was found that the friction coefficient and wear rate was closely related to the normal load and sliding speed, i.e., the friction coefficient of the prepared TiCu 2 Al intermetallic compound coating decreased with increasing normal load and sliding speed. The wear rate of the TiCu 2 Al intermetallic compound coating decreased rapidly with increasing sliding speed, while the wear rate first increased and then decreased at normal load from 5 to 15 N.

Containerless automated processing of intermetallic compounds and composites

Science.gov (United States)

Johnson, D. R.; Joslin, S. M.; Reviere, R. D.; Oliver, B. F.; Noebe, R. D.

1993-01-01

An automated containerless processing system has been developed to directionally solidify high temperature materials, intermetallic compounds, and intermetallic/metallic composites. The system incorporates a wide range of ultra-high purity chemical processing conditions. The utilization of image processing for automated control negates the need for temperature measurements for process control. The list of recent systems that have been processed includes Cr, Mo, Mn, Nb, Ni, Ti, V, and Zr containing aluminides. Possible uses of the system, process control approaches, and properties and structures of recently processed intermetallics are reviewed.

Studies about interaction of hydrogen isotopes with metals and intermetallic compounds

International Nuclear Information System (INIS)

Vasut, F.; Anisoara, P.; Zamfirache, M.

2003-01-01

Hydrogen is a non-toxic but highly inflammable gas. Compared to other inflammable gases, its range of inflammability in air is much broader (4-74.5%) but it also vaporizes much more easily. Handling of hydrogen in form of hydrides enhances safety. The interaction of hydrogen with metals and intermetallic compounds is a major field within physical chemistry. Using hydride-forming metals and intermetallic compounds, for example, recovery, purification and storage of heavy isotopes in tritium containing system can solve many problems arising in the nuclear-fuel cycle. The paper presents the thermodynamics and the kinetics between hydrogen and metal or intermetallic compounds. (author)

Crystal field in rare-earth metals and intermetallic compounds

International Nuclear Information System (INIS)

Ray, D.K.

1978-01-01

Reasons for the success of the crystal-field model for the rare-earth metals and intermetallic compounds are discussed. A review of some of the available experimental results is made with emphasis on cubic intermetallic compounds. Various sources of the origin of the crystal field in these metals are discussed in the background of the recent APW picture of the conduction electrons. The importance of the non-spherical part of the muffin-tin potential on the single-ion anisotropy is stressed. (author)

Microstructure and tribological properties of TiCu{sub 2}Al intermetallic compound coating

Energy Technology Data Exchange (ETDEWEB)

Guo Chun, E-mail: guochun@licp.cas.cn [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Graduate University of Chinese Academy of Sciences, Beijing 100039 (China); Zhou Jiansong [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Zhao Jierong; Wang Linqian; Yu Youjun [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Graduate University of Chinese Academy of Sciences, Beijing 100039 (China); Chen Jianmin; Zhou Huidi [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

2011-04-15

TiCu{sub 2}Al ternary intermetallic compound coating has been in situ synthesized successfully on pure Ti substrate by laser cladding. Tribological properties of the prepared TiCu{sub 2}Al intermetallic compound coating were systematically evaluated. It was found that the friction coefficient and wear rate was closely related to the normal load and sliding speed, i.e., the friction coefficient of the prepared TiCu{sub 2}Al intermetallic compound coating decreased with increasing normal load and sliding speed. The wear rate of the TiCu{sub 2}Al intermetallic compound coating decreased rapidly with increasing sliding speed, while the wear rate first increased and then decreased at normal load from 5 to 15 N.

Hydrogenations of alloys and intermetallic compounds of magnesium

International Nuclear Information System (INIS)

Gavra, Z.

1981-08-01

A kinetic and thermodynamic study of the hydrogenation of alloys and intermetallic compounds of magnesium is presented. It was established that the addition of elements of the IIIA group (Al, Ga, In) to magnesium catalyses its hydrogenation. This is explained by the mechanism of diffusion of magnesium cation vacancies. The hydride Mg 2 NiH 4 was characterized by thermal analysis, x-ray diffraction and NMR measurements. The possibility of forming pseudo-binary compounds of Mg 2 Ni by the substitution of nickel or magnesium was examined. The hydrogenation of the inter-metallic compounds of the Mg-Al system was investigated. It was found that the addition of indium and nickel affected the hydrogenation kinetics. A preliminary study of the hydrogenation of various binary and ternary alloys of magnesium was carried out. (Author)

Diffusion mechanisms in intermetallic compounds

Energy Technology Data Exchange (ETDEWEB)

Larikov, L N [ANU, Inst. Metallofiziki, Kiev (Ukraine)

1992-08-01

Recent research aimed at the identification of the principal mechanisms of diffusion in intermetallics is reviewed. In particular, attention is given to the effect of the type of interatomic bond on the contribution of different mechanisms to diffusion in ordered metallic compounds. Results of an analysis of experimental determinations of diffusion coefficients D(A) and D(B) in binary intermetallics (CuZn, Cu3Sn, AuCd, AgZn, AgMg, InSb, GaSb, AlSb, Fe3Al, FeAl, FeAl3, Ni3Al, Ni3Nb, FeSn, FeSn2, Ni3Sn2, Ni3Sn4, Co3Sn2, CoSn, CoSn2, and CoGa) are presented, and it is shown that the D(A)/D(B) ratio differs substantially for different diffusion mechanisms. 60 refs.

Large positive magnetoresistance in intermetallic compound NdCo2Si2

Science.gov (United States)

Roy Chowdhury, R.; Dhara, S.; Das, I.; Bandyopadhyay, B.; Rawat, R.

2018-04-01

The magnetic, magneto-transport and magnetocaloric properties of antiferromagnetic intermetallic compound NdCo2Si2 (TN = 32K) have been studied. The compound yields a positive magnetoresistance (MR) of about ∼ 123 % at ∼ 5K in 8 T magnetic field. The MR value is significantly large vis - a - vis earlier reports of large MR in intermetallic compounds, and possibly associated with the changes in magnetic structure of the compound. The large MR value can be explained in terms of field induced pseudo-gaps on Fermi surface.

Oxygen stabilized rare-earth iron intermetallic compounds

International Nuclear Information System (INIS)

Dariel, M.P.; Malekzadeh, M.; Pickus, M.R.

1975-10-01

A new, oxygen-stabilized intermetallic compound was identified in sintered, pre-alloyed rare-earth iron powder samples. Its composition corresponds to formula R 12 Fe 32 O 2 and its crystal structure belongs to space group Im3m. The presence of these compounds was observed, so far, in several R--Fe--O systems, with R = Gd, Tb, Dy, Ho, Er, and Y

Preparation of Ti3Al intermetallic compound by spark plasma sintering

Science.gov (United States)

Ito, Tsutomu; Fukui, Takahiro

2018-04-01

Sintered compacts of single phase Ti3Al intermetallic compound, which have excellent potential as refractory materials, were prepared by spark plasma sintering (SPS). A raw powder of Ti3Al intermetallic compound with an average powder diameter of 176 ± 56 μm was used in this study; this large powder diameter is disadvantageous for sintering because of the small surface area. The samples were prepared at sintering temperatures (Ts) of 1088, 1203, and 1323 K, sintering stresses (σs) of 16, 32, and 48 MPa, and a sintering time (ts) of 10 min. The calculated relative densities based on the apparent density of Ti3Al provided by the supplier were approximately 100% under all sintering conditions. From the experimental results, it was evident that SPS is an effective technique for dense sintering of Ti3Al intermetallic compounds in a short time interval. In this report, the sintering characteristics of Ti3Al intermetallic compacts are briefly discussed and compared with those of pure titanium compacts.

Effects of iron on intermetallic compound formation in scandium modified Al–Si–Mg Alloys

Energy Technology Data Exchange (ETDEWEB)

Patakham, Ussadawut [National Metal and Materials Technology Center, National Science and Technology Development Agency, 114 Thailand Science Park, Klong Nueng, Klong Luang, Pathumthani 12120 (Thailand); Limmaneevichitr, Chaowalit, E-mail: chaowalit.lim@mail.kmutt.ac.th [Production Engineering Department, Faculty of Engineering, King Mongkut’s University of Technology Thonburi, 126 Pracha-Utid Rd., Bangmod, Tungkhru, Bangkok 10140 (Thailand)

2014-12-15

Highlights: • Iron reduces the modification effects of scandium in Al–Si–Mg alloys. • Morphologies of Sc-rich intermetallic phases vary with Fe and Sc contents and the cooling rates. • Sc neutralizes effects of Fe by changing Fe-rich intermetallic phases from platelets to more cubic. - Abstract: In general, iron has a strong tendency to dissolve in molten aluminum. Iron has very low solid solubility in aluminum–silicon casting alloys, so it will form intermetallic compounds that cause detrimental effects on mechanical properties. In this work, the effects of iron on intermetallic compound formations in scandium modified Al–Si–Mg alloys were studied. There were two levels of iron addition (0.2 and 0.4 wt.%) and two levels of scandium addition (0.2 and 0.4 wt.%). We found that the effects of scandium modification decreased with increasing iron addition. The morphologies of the complex intermetallic compounds were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and electron backscatter diffraction (EBSD) techniques. It was found that scandium changes the morphology of Fe-rich intermetallic compounds from β-phase (plate-like) to α-phase, which reduces the harmful effects of β-phase.

A Correlation between the Ultimate Shear Stress and the Thickness Affected by Intermetallic Compounds in Friction Stir Welding of Dissimilar Aluminum Alloy–Stainless Steel Joints

Directory of Open Access Journals (Sweden)

Florent Picot

2018-03-01

Full Text Available In this work, Friction Stir Welding (FSW was applied to join a stainless steel 316L and an aluminum alloy 5083. Ranges of rotation and translation speeds of the tool were used to obtain welding samples with different heat input coefficients. Depending on the process parameters, the heat generated by FSW creates thin layers of Al-rich InterMetallic Compound (IMC mainly composed of FeAl3, identified by energy dispersive spectrometry. Traces of Fe2Al5 were also depicted in some samples by X-ray diffraction analysis and transmission electron microscopy. Monotonous tensile tests performed on the weld joint show the existence of a maximum mechanical resistance for a judicious choice of rotation and translation speeds. It can be linked to an affected zone of average thickness of 15 µm which encompass the presence of IMC and the chaotic mixing caused by plastic deformation in this area. A thickness of less than 15 µm is not sufficient to ensure a good mechanical resistance of the joint. For a thickness higher than 15 µm, IMC layers become more brittle and less adhesive due to high residual stresses which induces numerous cracks after cooling. This leads to a progressive decrease of the ultimate shear stress supported by the bond.

Codeformation processing of mechanically-dissimilar metal/intermetallic composites

Science.gov (United States)

Marte, Judson Sloan

A systematic and scientific approach has been applied to the study of codeformation processing. A series of composites having mechanically-dissimilar phases were developed in which the high temperature flow behavior of the reinforcement material could be varied independent of the matrix. This was accomplished through the use of a series of intermetallic matrix composites (IMCs) as discontinuous reinforcements in an otherwise conventional metal matrix composite. The IMCs are produced using an in-situ reaction synthesis technique, called the XD(TM) process. The temperature of the exothermic synthesis reaction, called the adiabatic temperature, has been calculated and shown to increase with increasing volume percentage of TiB2 reinforcement. Further, this temperature has been shown to effect the size and spacing of the TiB2, microstructural features which are often used in discontinuous composite strength models. Study of the high temperature flow behavior of the components of the metal/IMC composite is critical to the development of an understanding of codeformation. A series of compression tests performed at 1000° to 1200°C and strain-rates of 10-3 and 10-4 sec-1. Peak flow stresses were used to evaluate the influence of material properties and process conditions. These data were incorporated into phenomenologically-based constitutive equations that have been used to predict the flow behavior. It has been determined that plastic deformation of the IMCs occurs readily, and is largely TiB2 independent, at temperatures approaching the melting point of the intermetallic matrices. Ti-6Al-4V/IMC powder blends were extruded at high temperatures to achieve commensurately deformed microstructures. The results of codeformation processing were analyzed in terms of the plastic strain of the IMC particulates. IMC particle deformation was shown to increase with increasing IMC particle size, volume percentage of IMC, extrusion temperature, homologous temperature, extrusion

Effect of Ni addition to the Cu substrate on the interfacial reaction and IMC growth with Sn3.0Ag0.5Cu solder

Science.gov (United States)

Zhang, Xudong; Hu, Xiaowu; Jiang, Xiongxin; Li, Yulong

2018-04-01

The formation and growth of intermetallic compound (IMC) layer at the interface between Sn3.0Ag0.5Cu (SAC305) solder and Cu- xNi ( x = 0, 0.5, 1.5, 5, 10 wt%) substrate during reflowing and aging were investigated. The soldering was conducted at 270 °C using reflowing method, following by aging treatment at 150 °C for up to 360 h. The experimental results indicated that the total thickness of IMC increased with increasing aging time. The scallop-like Cu6Sn5 and planar-like Cu3Sn IMC layer were observed between SAC305 solder and purely Cu substrate. As the content of Ni element in Cu substrate was 0.5% or 1.5%, the scallop-like Cu6Sn5 and planar-like Cu3Sn IMC layer were still found between solder and Cu-Ni substrate and the total thickness of IMC layer decreased with the increasing Ni content. Besides, when the Ni content was up to 5%, the long prismatic (Cu,Ni)6Sn5 phase was the only product between solder and substrate and the total thickness of IMC layer increased significantly. Interestingly, the total thickness of IMC decreased slightly as the Ni addition was up to 10%. In the end, the grains of interfacial IMC layer became coarser with aging time increasing while the addition of Ni in Cu substrate could refine IMC grains.

An Investigation of the Microstructure of an Intermetallic Layer in Welding Aluminum Alloys to Steel by MIG Process.

Science.gov (United States)

Nguyen, Quoc Manh; Huang, Shyh-Chour

2015-12-02

Butt joints of A5052 aluminum alloy and SS400 steel, with a new type of chamfered edge, are welded by means of metal inert gas welding and ER4043 Al-Si filler metal. The microhardness and microstructure of the joint are investigated. An intermetallic layer is found on the surface of the welding seam and SS400 steel sheet. The hardness of the intermetallic layer is examined using the Vickers hardness test. The average hardness values at the Intermetallic (IMC) layer zone and without the IMC layer zone were higher than that of the welding wire ER4043. The tensile strength test showed a fracture at the intermetallic layer when the tensile strength is 225.9 MPa. The tensile value test indicated the average of welds was equivalent to the 85% tensile strength of the A5052 aluminum alloy. The thickness of the intermetallic layers is non-uniform at different positions with the ranges from 1.95 to 5 μm. The quality of the butt joint is better if the intermetallic layer is minimized. The Si crystals which appeared at the welding seam, indicating that this element participated actively during the welding process, also contributed to the IMC layer's formation.

The behavior of intermetallic compounds at large plastic strains

International Nuclear Information System (INIS)

Gray, G.T.; Embury, J.D.

1993-01-01

This paper contains a summary of a broad study of intermetallics which includes the following materials, Ni 3 Al, Ti-48Al-1V, Ti-24Al-11Nb, Ti-48Al-2Cr-2Nb, and Ti-24.5 Al-10.5Nb-1.5Mo. Much effort has been devoted to the study of ordered materials at modes plastic strains and the problem of premature failure. However by utilizing stress states other than simple tension it is possible to study the deformation of intermetallic compounds up to large plastic strains and to consider the behavior of these materials in the regime where stresses approach the theoretical stress. The current work outlines studies of the work hardening rate of a number of titanium and nickel-based intermetallic compounds deformed in compression. Attention is given to the structural basis of the sustained work hardening. The large strain plasticity of these materials is summarized in a series of diagrams. Fracture in these materials in compression occurs via catastrophic shear at stresses of the order of E/80 (where E is the elastic modulus)

Structural and Electronic Investigations of Complex Intermetallic Compounds

Energy Technology Data Exchange (ETDEWEB)

Ko, Hyunjin [Iowa State Univ., Ames, IA (United States)

2008-01-01

In solid state chemistry, numerous investigations have been attempted to address the relationships between chemical structure and physical properties. Such questions include: (1) How can we understand the driving forces of the atomic arrangements in complex solids that exhibit interesting chemical and physical properties? (2) How do different elements distribute themselves in a solid-state structure? (3) Can we develop a chemical understanding to predict the effects of valence electron concentration on the structures and magnetic ordering of systems by both experimental and theoretical means? Although these issues are relevant to various compound classes, intermetallic compounds are especially interesting and well suited for a joint experimental and theoretical effort. For intermetallic compounds, the questions listed above are difficult to answer since many of the constituent atoms simply do not crystallize in the same manner as in their separate, elemental structures. Also, theoretical studies suggest that the energy differences between various structural alternatives are small. For example, Al and Ga both belong in the same group on the Periodic Table of Elements and share many similar chemical properties. Al crystallizes in the fcc lattice with 4 atoms per unit cell and Ga crystallizes in an orthorhombic unit cell lattice with 8 atoms per unit cell, which are both fairly simple structures (Figure 1). However, when combined with Mn, which itself has a very complex cubic crystal structure with 58 atoms per unit cell, the resulting intermetallic compounds crystallize in a completely different fashion. At the 1:1 stoichiometry, MnAl forms a very simple tetragonal lattice with two atoms per primitive unit cell, while MnGa crystallizes in a complicated rhombohedral unit cell with 26 atoms within the primitive unit cell. The mechanisms influencing the arrangements of atoms in numerous crystal structures have been studied theoretically by calculating electronic

The effect of intermetallic compound morphology on Cu diffusion in Sn-Ag and Sn-Pb solder bump on the Ni/Cu Under-bump metallization

Science.gov (United States)

Jang, Guh-Yaw; Duh, Jenq-Gong

2005-01-01

The eutectic Sn-Ag solder alloy is one of the candidates for the Pb-free solder, and Sn-Pb solder alloys are still widely used in today’s electronic packages. In this tudy, the interfacial reaction in the eutectic Sn-Ag and Sn-Pb solder joints was investigated with an assembly of a solder/Ni/Cu/Ti/Si3N4/Si multilayer structures. In the Sn-3.5Ag solder joints reflowed at 260°C, only the (Ni1-x,Cux)3Sn4 intermetallic compound (IMC) formed at the solder/Ni interface. For the Sn-37Pb solder reflowed at 225°C for one to ten cycles, only the (Ni1-x,Cux)3Sn4 IMC formed between the solder and the Ni/Cu under-bump metallization (UBM). Nevertheless, the (Cu1-y,Niy)6Sn5 IMC was observed in joints reflowed at 245°C after five cycles and at 265°C after three cycles. With the aid of microstructure evolution, quantitative analysis, and elemental distribution between the solder and Ni/Cu UBM, it was revealed that Cu content in the solder near the solder/IMC interface played an important role in the formation of the (Cu1-y,Niy)6Sn5 IMC. In addition, the diffusion behavior of Cu in eutectic Sn-Ag and Sn-Pb solders with the Ni/Cu UBM were probed and discussed. The atomic flux of Cu diffused through Ni was evaluated by detailed quantitative analysis in an electron probe microanalyzer (EPMA). During reflow, the atomic flux of Cu was on the order of 1016-1017 atoms/cm2sec in both the eutectic Sn-Ag and Sn-Pb systems.

Miniaturization of Micro-Solder Bumps and Effect of IMC on Stress Distribution

Science.gov (United States)

Choudhury, Soud Farhan; Ladani, Leila

2016-07-01

As the joints become smaller in more advanced packages and devices, intermetallic (IMCs) volume ratio increases, which significantly impacts the overall mechanical behavior of joints. The existence of only a few grains of Sn (Tin) and IMC materials results in anisotropic elastic and plastic behavior which is not detectable using conventional finite element (FE) simulation with average properties for polycrystalline material. In this study, crystal plasticity finite element (CPFE) simulation is used to model the whole joint including copper, Sn solder and Cu6Sn5 IMC material. Experimental lap-shear test results for solder joints from the literature were used to validate the models. A comparative analysis between traditional FE, CPFE and experiments was conducted. The CPFE model was able to correlate the experiments more closely compared to traditional FE analysis because of its ability to capture micro-mechanical anisotropic behavior. Further analysis was conducted to evaluate the effect of IMC thickness on stress distribution in micro-bumps using a systematic numerical experiment with IMC thickness ranging from 0% to 80%. The analysis was conducted on micro-bumps with single crystal Sn and bicrystal Sn. The overall stress distribution and shear deformation changes as the IMC thickness increases. The model with higher IMC thickness shows a stiffer shear response, and provides a higher shear yield strength.

Behavior of aluminum oxide, intermetallics and voids in Cu-Al wire bonds

International Nuclear Information System (INIS)

Xu, H.; Liu, C.; Silberschmidt, V.V.; Pramana, S.S.; White, T.J.; Chen, Z.; Acoff, V.L.

2011-01-01

Nanoscale interfacial evolution in Cu-Al wire bonds during isothermal annealing from 175 deg. C to 250 deg. C was investigated by high resolution transmission electron microscopy (HRTEM). The native aluminum oxide film (∼5 nm thick) of the Al pad migrates towards the Cu ball during annealing. The formation of intermetallic compounds (IMC) is controlled by Cu diffusion, where the kinetics obey a parabolic growth law until complete consumption of the Al pad. The activation energies to initiate crystallization of CuAl 2 and Cu 9 Al 4 are 60.66 kJ mol -1 and 75.61 kJ mol -1 , respectively. During IMC development, Cu 9 Al 4 emerges as a second layer and grows together with the initial CuAl 2 . When Al is completely consumed, CuAl 2 transforms to Cu 9 Al 4 , which is the terminal product. Unlike the excessive void growth in Au-Al bonds, only a few voids nucleate in Cu-Al bonds after long-term annealing at high temperatures (e.g., 250 o C for 25 h), and their diameters are usually in the range of tens of nanometers. This is due to the lower oxidation rate and volumetric shrinkage of Cu-Al IMC compared with Au-Al IMC.

Soldering-induced Cu diffusion and intermetallic compound formation between Ni/Cu under bump metallization and SnPb flip-chip solder bumps

Science.gov (United States)

Huang, Chien-Sheng; Jang, Guh-Yaw; Duh, Jenq-Gong

2004-04-01

Nickel-based under bump metallization (UBM) has been widely used as a diffusion barrier to prevent the rapid reaction between the Cu conductor and Sn-based solders. In this study, joints with and without solder after heat treatments were employed to evaluate the diffusion behavior of Cu in the 63Sn-37Pb/Ni/Cu/Ti/Si3N4/Si multilayer structure. The atomic flux of Cu diffused through Ni was evaluated from the concentration profiles of Cu in solder joints. During reflow, the atomic flux of Cu was on the order of 1015-1016 atoms/cm2s. However, in the assembly without solder, no Cu was detected on the surface of Ni even after ten cycles of reflow. The diffusion behavior of Cu during heat treatments was studied, and the soldering-process-induced Cu diffusion through Ni metallization was characterized. In addition, the effect of Cu content in the solder near the solder/intermetallic compound (IMC) interface on interfacial reactions between the solder and the Ni/Cu UBM was also discussed. It is evident that the (Cu,Ni)6Sn5 IMC might form as the concentration of Cu in the Sn-Cu-Ni alloy exceeds 0.6 wt.%.

Thermochemical investigations on intermetallic UMe3 compounds (Me=Ru,Rh,Pd)

International Nuclear Information System (INIS)

Wijbenga, G.

1981-10-01

The subject of this thesis is the determination of the thermodynamic properties of the intermetallic compounds of uranium with the light platinum metals, ruthenium, rhodium and palladium. These intermetallics are formed as very stable compounds during fission in nuclear fuel by the reaction of the fission products Ru, Rh and Pd with the matrix. Methods for the preparation of URu 3 , URh 3 and UPd 3 , experiments showing the chemical reactivities of these compounds, and studies of the stoichiometry of hexagonal UPd 3 by X-ray diffraction of solubility experiments of UN and palladium in UPd 3 , are described. Thermodynamic properties of the UMe 3 compounds have been obtained using several experimental thermodynamic techniques: fluorine bomb calorimetry, low-temperature cryogenic calorimetry, high-temperature drop calorimetry and EMF measurements of reversible cells. (Auth.)

Charge and spin density in s-stable rare earth intermetallic compounds

International Nuclear Information System (INIS)

Graaf, H. de.

1982-01-01

This thesis deals with a study of the electronic structure of rare earth intermetallic compounds, in particular the electronic charge and spin density distribution. These are closely related to the properties of the rare earth ions, which carry the partly filled 4f shell. In chapter 1 a survey of the theory of hyperfine interaction as far as it has a bearing on the Moessbauer effect of 155 Gd and 151 Eu is given. Also some details of the Moessbauer spectra, which have practical importance are discussed. In chapter 2 the experimental set-up is described. Special attention is paid to the gamma radiation source and gamma detection requirements. In chapter 3 the author introduces the theoretical framework which will be used to interpret the measurements. In chapter 4 the results of the 155 Gd Moessbauer measurements are presented. Also it is discussed how the result can be understood in terms of the charge and spin density in rare earth intermetallic compounds. In order to lend support to the picture emerging from the previous chapter, in chapter 5 the conduction electron band structure of some representative Gd intermetallics is computed with an approximate semi-empirical LCAO method. The results are compared with those from chapter 4. Finally, in chapter 6, the 151 Eu resonance is used to investigate the temperature dependence of the hyperfine field and line width in the Eu intermetallic compounds Eu 2 Mg 17 and EuMg 5 . (Auth.)

Environmental embrittlement of intermetallic compounds in Fe-Al alloys

Institute of Scientific and Technical Information of China (English)

张建民; 张瑞林; S.H.YU; 余瑞璜

1996-01-01

First,it is proposed that hydrogen atoms occupy the interstitial sites in Fe3Al and FeAl.Then the environmental embrittlement of intermetallic compounds in Fe-Al alloys is studied in the light of calculated valence electron structures and bond energy of Fe3Al and FeAl containing hydrogen atoms.From the analyses it is found that the states of metal atoms will change,in which more lattice electrons will become covalent electrons to bond with hydrogen atoms when the atomic hydrogen diffuses into the intermetallic compounds in Fe-Al alloys,which will result in the decrease of local metallicity in Fe3Al and FeAl.Meanwhile,it is found that the crystal will easily cleave since solute hydrogen bonds with metal atoms and severely anisotropic bonds form.As a conclusion,these factors result in the environmental embrittlement of Fe3Al and FeAl.

Incorporation of Interfacial Intermetallic Morphology in Fracture Mechanism Map for Sn-Ag-Cu Solder Joints

Science.gov (United States)

Huang, Z.; Kumar, P.; Dutta, I.; Sidhu, R.; Renavikar, M.; Mahajan, R.

2014-01-01

A fracture mechanism map (FMM) is a powerful tool which correlates the fracture behavior of a material to its microstructural characteristics in an explicit and convenient way. In the FMM for solder joints, an effective thickness of the interfacial intermetallic compound (IMC) layer ( t eff) and the solder yield strength ( σ ys,eff) are used as abscissa and ordinate axes, respectively, as these two predominantly affect the fracture behavior of solder joints. Earlier, a definition of t eff, based on the uniform thickness of IMC ( t u) and the average height of the IMC scallops ( t s), was proposed and shown to aptly explain the fracture behavior of solder joints on Cu. This paper presents a more general definition of t eff that is more widely applicable to a range of metallizations, including Cu and electroless nickel immersion gold (ENIG). Using this new definition of t eff, mode I FMM for SAC387/Cu joints has been updated and its validity was confirmed. A preliminary FMM for SAC387/Cu joints with ENIG metallization is also presented.

2. Intermetallic compounds with lanthanides

International Nuclear Information System (INIS)

Elemans, J.B.A.A.

1975-01-01

Theoretical considerations are given concerning the structures of intermetallic compounds of the lanthanides and thorium (R) on the one hand, and with Fe, Co or Ni (M) on the other. They all derive from the parent composition RM 5 with the CaCu 5 hexagonal structure. This consists of alternate layers in which the M atoms are distinguished as M 1 and M 2 . The other compounds whose structures are studied are obtained by systematic replacement of R by M, or vice versa. In the first type, every third R is replaced by two M's yielding R 2 M 17 compounds. The substitution may be truly random or structured in two ways: so that either the hexagonal structure is maintained or that it is converted into a rhombihedral one. In the second type, one M (in a M 1 position) out of every five is replaced by one R, giving rise to RM 2 compounds which form Laves phases. In the third type, the M 1 's are replaced by R's, resulting in compounds RM 3 . In the fourth type, every third M is replaced by R, yielding R 2 M 7 compounds. With M = Co and R a light lanthanide, the compounds are ferromagnets; with R yttrium, thorium, or a heavy lanthanide, they are ferrimagnets. The preparation of the compounds in an arc-melting apparatus under an Ar-atmosphere followed by annealing is described

Experimental and computational study of the morphological evolution of intermetallic compound (Cu6Sn5) layers at the Cu/Sn interface under isothermal soldering conditions

International Nuclear Information System (INIS)

Park, M.S.; Stephenson, M.K.; Shannon, C.; Cáceres Díaz, L.A.; Hudspeth, K.A.; Gibbons, S.L.; Muñoz-Saldaña, J.; Arróyave, R.

2012-01-01

Cu/Sn soldering alloys have emerged as a viable alternative to Pb-based solders, and thus have been extensively explored in the past decade, although the fine-scale behavior of the resulting intermetallic compounds (IMCs), particularly during the early stages of interface formation, is still a source of debate. In this work, the microstructural evolution of Cu 6 Sn 5 , in a Cu/Sn soldering reaction at 523 K, was experimentally investigated by dipping a single Cu sample into molten Sn at a near-constant speed, yielding a continuous set of time evolution samples. The thickness, coarsening and morphology evolution of the Cu 6 Sn 5 layer is investigated through the use of scanning electron microscopy. The experimental results are also compared to phase-field simulations of the microstructural evolution of the Cu 6 Sn 5 layer. The influence of model parameters on the kinetics and morphological evolution of the IMC layer was examined. In general, good qualitative agreement is found between experiments and simulations and for a limited parameter set there appears to be good quantitative agreement between the growth kinetics of the Cu 6 Sn 5 layer, the grain boundary (GB) effect on grain coarsening, and the substrate/IMC interface roughness evolution. Furthermore, the parametric investigations of the model suggests that good agreement between experiments and simulations is achieved when the dominant transport mechanism for the reacting elements (Cu and Sn) is GB diffusion.

Asymmetrical Precipitation of Ag3Sn Intermetallic Compounds Induced by Thermomigration of Ag in Pb-Free Microbumps During Solid-State Aging

Science.gov (United States)

Su, Yu-Ping; Wu, Chun-Sen; Ouyang, Fan-Yi

2016-01-01

Three-dimensional integrated circuit technology has become a major trend in electronics packaging in the microelectronics industry. To effectively remove heat from stacked integrated circuitry, a temperature gradient must be established across the chips. Furthermore, because of the trend toward higher device current density, Joule heating is more serious and temperature gradients across soldered joints are expected to increase. In this study we used heat-sink and heat-source devices to establish a temperature gradient across SnAg microbumps to investigate the thermomigration behavior of Ag in SnAg solder. Compared with isothermal conditions, small Ag3Sn particles near the hot end were dissolved and redistributed toward the cold end under a temperature gradient. The results indicated that temperature gradient-induced movement of Ag atoms occurred from the hot side toward the cold side, and asymmetrical precipitation of Ag3Sn resulted. The mechanism of growth of the intermetallic compound (IMC) Ag3Sn, caused by thermomigration of Ag, is discussed. The rate of growth Ag3Sn IMC at the cold side was found to increase linearly with solid-aging time under a temperature gradient. To understand the force driving Ag diffusion under the temperature gradient, the molar heat of transport ( Q*) of Ag in Sn was calculated as +13.34 kJ/mole.

Intermetallic compound development for the 21st century

International Nuclear Information System (INIS)

Munroe, P.R.

2000-01-01

lntermetallic compounds have been vigorously researched for the past twenty years. As a result of these studies the fundamental behaviour of a number of transition metal aluminides and suicides is now well understood, and a number of alloys with commercially acceptable properties have been developed. Future challenges for these alloys, for example Ni 3 AI, TiAI and Fe 3 AI, are focused on the development of large-scale production routes. However, there remain a number of other intermetallic compounds, such as Laves phases, which exhibit some promising properties, but little is presently known about their intrinsic behaviour. For compounds such as these more fundamental studies are required

Development of melting and casting process for Nb-Al intermetallic compounds and mechanical properties

International Nuclear Information System (INIS)

Kamata, Kinya; Degawa, Toru; Nagashima, Yoshinori

1993-01-01

The shaping methods of Nb-Al intermetallic compounds, especially melting and casting, have considerably different characteristics as compared with those for other metals and alloys. The authors have investigated melting and casting processes for Nb-Al compounds to develop precision casting processes for these intermetallics. Fundamental properties of Nb-Al compound castings have been also investigated for high temperature structural use in this work. An advanced Induction Skull Melting (ISM) furnace has been developed and the advantages of ISM have been recognized as a result of this study. The mechanical properties, such as hardness and compression strength, are dependent upon the Al content in Nb-Al binary compounds

Phase transformation and morphology of the intermetallic compounds formed at the Sn-9Zn-3.5Ag/Cu interface in aging

International Nuclear Information System (INIS)

Hon, M.-H.; Chang, T.-C.; Wang, M.-C.

2008-01-01

The morphology and phase transformation of the intermetallic compounds (IMCs) formed at the Sn-9Zn-3.5Ag/Cu interface in a solid-state reaction have been investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), electron diffraction (ED), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). The monoclinic η'-Cu 6 Sn 5 transforms to the hexagonal η-Cu 6 Sn 5 and the orthorhombic Cu 5 Zn 8 transforms to the body-centered cubic (bcc) γ-Cu 5 Zn 8 as aged at 180 deg. C. The scallop-shaped Cu 6 Sn 5 layer is retained after aging at 180 deg. C for 1000 h. In the solid-state reaction, Ag is repelled from η'-Cu 6 Sn 5 and reacts with Sn to form Ag 3 Sn, and the Cu 5 Zn 8 layer decomposes. Kirkendall voids are not observed at the Sn-9Zn-3.5Ag/Cu interface even after aging at 180 deg. C for 1000 h

Lattice and magnetic anisotropies in uranium intermetallic compounds

DEFF Research Database (Denmark)

Havela, L.; Mašková, S.; Adamska, A.

2013-01-01

Examples of UNiAlD and UCoGe illustrate that the soft crystallographic direction coincides quite generally with the shortest U-U links in U intermetallics. Added to existing experimental evidence on U compounds it leads to a simple rule, that the easy magnetization direction and the soft crystall...... crystallographic direction (in the sense of highest compressibility under hydrostatic pressure) must be mutually orthogonal....

Thermal Expansion of Ni3Al Intermetallic Compound: Experiment and Simulation

International Nuclear Information System (INIS)

Wang Hai-Peng; Lü Peng; Zhou Kai; Wei Bing-Bo

2016-01-01

The thermal expansion of Ni 3 Al intermetallic compound is determined by a thermal dilatometer and simulated by the molecular dynamics method. The results of the linear thermal expansion coefficients are presented from 200 K up to the maximum temperature of 1600 K. The single phase of Ni 3 Al intermetallic compound is confirmed by x-ray diffraction together with DSC melting and solidification peaks, from which the solidus and the liquidus temperatures are obtained to be 1660 and 1695 K, respectively. The measured linear thermal expansion coefficient increases from 1.5 × 10 −5 to 2.7 × 10 −5 K −1 in the experimental temperature range, in good agreement with the data obtained by the molecular dynamics simulation, just a slight difference from the temperature dependence coefficient. Furthermore, the atomic structure and position are presented to reveal the atom distribution change during thermal expansion of Ni 3 Al compound. (paper)

X-Ray Diffraction of Intermetallic Compounds: A Physical Chemistry Laboratory Experiment

Science.gov (United States)

Varberg, Thomas D.; Skakuj, Kacper

2015-01-01

Here we describe an experiment for the undergraduate physical chemistry laboratory in which students synthesize the intermetallic compounds AlNi and AlNi3 and study them by X-ray diffractometry. The compounds are synthesized in a simple one-step reaction occurring in the solid state. Powder X-ray diffractograms are recorded for the two compounds…

A new method to estimate the atomic volume of ternary intermetallic compounds

International Nuclear Information System (INIS)

Pani, M.; Merlo, F.

2011-01-01

The atomic volume of an A x B y C z ternary intermetallic compound can be calculated starting from volumes of some proper A-B, A-C and B-C binary phases. The three methods by Colinet, Muggianu and Kohler, originally used to estimate thermodynamic quantities, and a new method here proposed, were tested to derive volume data in eight systems containing 91 ternary phases with the known structure. The comparison between experimental and calculated volume values shows the best agreement both for the Kohler method and for the new proposed procedure. -- Graphical abstract: Synopsys: the volume of a ternary intermetallic compound can be calculated starting from volumes of some binary phases, selected by the methods of Colinet, Muggianu, Kohler and a new method proposed here. The so obtained values are compared with the experimental ones for eight ternary systems. Display Omitted Research highlights: → The application of some thermodinamic methods to a crystallochemical problem. → The prevision of the average atomic volume of ternary intermetallic phases. → The proposal of a new procedure to select the proper starting set of binary phases.

Investigations on Ce- and Yb-based intermetallic compounds

International Nuclear Information System (INIS)

Elenbaas, R.A.

1980-01-01

The author describes investigations on a number of cerium- and ytterbium-based intermetallic compounds and alloys, yielding a lot of experimental results which could not always be put in a quantitative picture. All experimental data are consistent with a single-ion behaviour, where the 4f state is more or less modified by the conduction electrons. In the investigated systems several different features of the magnetism of cerium atoms in metals were studied. (Auth.)

Pitting Corrosion of Ni3(Si,Ti Intermetallic Compound at Various Chloride Concentrations

Directory of Open Access Journals (Sweden)

Gadang Priyotomo

2013-10-01

Full Text Available The pitting corrosion of Ni3(Si,Ti intermetallic compound was investigated as function of chloride concentration by using electrochemical method and scanning electron microscope in sodium chloride solutions at 293 K.  In addition, the pitting corrosion of type C276 alloy was also studied under the same experimental condition for comparison.  The pitting potential obtained for the intermetallic compound decreased with increasing chloride concentration.  The specific pitting potential and pitting potential of Ni3(Si,Ti were lower than those of C276 alloy, which means that the pitting corrosion resistance of C276 alloy was higher than that of Ni3(Si,Ti.

Real structure and selected properties of the superconducting intermetallic compound V3Si

International Nuclear Information System (INIS)

Kleinstueck, K.; Kraemer, U.; Paufler, P.; Ullrich, H.J.

1980-01-01

Plasticity and electro-plastic effects have been detected at temperatures above 1200 0 C in the intermetallic compound V 3 Si which can not plastically be deformed under normal conditions. The mechanisms of plastic deformation were elucidated. The critical temperature and the critical current density could be altered by plastic deformation. It was found that the mechanisms of plastic deformation as well as the alteration of the critical parameters are dependent on the chemical composition of the intermetallic compound within the range of homogeneity. For measuring such alterations Kossel's interference method was used. Intense plastic deformation of crystals resulted in an influence on the martensite transformation

Discovery of Intermetallic Compounds from Traditional to Machine-Learning Approaches.

Science.gov (United States)

Oliynyk, Anton O; Mar, Arthur

2018-01-16

Intermetallic compounds are bestowed by diverse compositions, complex structures, and useful properties for many materials applications. How metallic elements react to form these compounds and what structures they adopt remain challenging questions that defy predictability. Traditional approaches offer some rational strategies to prepare specific classes of intermetallics, such as targeting members within a modular homologous series, manipulating building blocks to assemble new structures, and filling interstitial sites to create stuffed variants. Because these strategies rely on precedent, they cannot foresee surprising results, by definition. Exploratory synthesis, whether through systematic phase diagram investigations or serendipity, is still essential for expanding our knowledge base. Eventually, the relationships may become too complex for the pattern recognition skills to be reliably or practically performed by humans. Complementing these traditional approaches, new machine-learning approaches may be a viable alternative for materials discovery, not only among intermetallics but also more generally to other chemical compounds. In this Account, we survey our own efforts to discover new intermetallic compounds, encompassing gallides, germanides, phosphides, arsenides, and others. We apply various machine-learning methods (such as support vector machine and random forest algorithms) to confront two significant questions in solid state chemistry. First, what crystal structures are adopted by a compound given an arbitrary composition? Initial efforts have focused on binary equiatomic phases AB, ternary equiatomic phases ABC, and full Heusler phases AB 2 C. Our analysis emphasizes the use of real experimental data and places special value on confirming predictions through experiment. Chemical descriptors are carefully chosen through a rigorous procedure called cluster resolution feature selection. Predictions for crystal structures are quantified by evaluating

An experimental study of praseodymium intermetallic compounds at low temperatures

International Nuclear Information System (INIS)

Greidanus, F.J.A.M.

1982-01-01

In this thesis the author studies the low temperature properties of praseodymium intermetallic compounds. In chapter 2 some of the techniques used for the experiments described in the subsequent chapters are discussed. A set-up to perform specific-heat experiments below 1 K and a technique for performing magnetic susceptibility measurments below 1 K, using a superconducting quantum interference device (SQUID) are described. Chapter 3 is devoted to the theory of interacting Pr 3+ ions. Both bilinear and biquadratic interactions are dealt with in a molecular-field approximation. It is shown that first as well as second-order phase transitions can occur, depending on the nature of the ground state, and on the ratio of magnetic to crystal-field interactions. In chapters 4, 5, 6 and 7 experimental results on the cubic Laves phase compounds PrRh 2 , PrIr 2 , PrPt 2 , PrRu 2 and PrNi 2 are presented. From inelastic neutron scattering experiments the crystalline electric field parameters of the above compounds are determined. In chapters 5 and 6 susceptibility, neutron-diffraction, hyperfine specific-heat, low-field magnetization, pulsed-field magnetization, specific-heat and resistivity measurements are presented. In chapter 7 the specific heat and differential susceptibility of PrNi 2 below 1 K are studied. Finally, in chapter 8 praseodymium intermetallic compounds with low-symmetry singlet ground states, and cubic compounds with magnetic doublet ground states are studied. (Auth.)

Spin polarization in rare earth intermetallic compounds

International Nuclear Information System (INIS)

Steenwijk, F.J. van

1976-01-01

In this thesis the results of Moessbauer experiments performed on a series of intermetallic compounds of europium and gadolinium are reported. For each of these compounds the magnetic hyperfine field, the electric field gradient at the nuclear site and the isomer shift were determined. For most of the compounds the magnetic ordering temperature was also measured. For some of the europium compounds (e.g. EuAu 5 , EuAg 5 , and EuCu 5 ) it could be derived from the measurements that the easy direction of magnetization falls along the crystallographic c-axis. In a number of compounds (e.g. EuCu 5 , EuZn 5 , EuAu 2 and GdCu 5 ), the various contributions to the magnetic hyperfine field were disentangled by the investigation of suitable pseudobinary compounds that are dilute in Eu. The neighbour contribution Hsub(N) and the paramagnetic Curie temperature thetasub(p) were compared with each other in terms of the RKKY model for EuCu 5 and GdCu 5 . Since the correspondence was found to be poor it was concluded that the magnetic behaviour in these compounds cannot be described by a simple free electron picture as is the basis for the RKKY model

New intermetallic compounds Ln(Ag, AL)4 (Ln-Y, Gd, Tb, Dy) and their structure

International Nuclear Information System (INIS)

Kuz'ma, Yu.B.; Stel'makhovich, B.M.

1990-01-01

By the methods of X-ray analysis crystal structure of compounds Ln(Ag,Al) 4 , where Ln-Y, Gd, Tb, Dy, posessing rhombic structure, is determined. The intermetallics have been prepared for the first time. Ways of atom distribution and their coordinates in DyAg 0.55 Al 3.45 structure (a=0.4296(1), b=04179(1), c=0.9995(3), R=0.093) are specified. Other compounds are formed in case of LnAgAl 3 compositions. Interatomic distances in Dy(Ag,Al) 4 structure are considered. A supposition is made on the formation in Ln-Ag-Al systems of a greater number of intermetallic compounds

Pressure effect on magnetic and magnetotransport properties of intermetallic and colossal magnetoresistance oxide compounds

International Nuclear Information System (INIS)

Arnold, Z; Ibarra, M R; Algarabel, P A; Marquina, C; Teresa, Jose MarIa de; Morellon, L; Blasco, J; Magen, C; Prokhnenko, O; Kamarad, J; Ritter, C

2005-01-01

The joint power of neutron diffraction and pressure techniques allows us to characterize under unique conditions the nature and different role of basic interactions in solids. We have covered a broad phenomenology in archetypical compounds: intermetallics and magnetic oxides. We have selected compounds in which the effect of moderate pressure is able to modify the electronic structure and bond angles that in turn are in the bases of magnetic and structural transitions. Complex magnetic and structural phase diagrams are reported for compounds with magnetic (Tb 1-X Y X Mn 2 ) and structural (RE 5 Si 4-X Ge X ) instabilities. Pressure-induced change of the magnetic structure in (R 2 Fe 17 ) intermetallics and the effect on the colossal magnetoresistance manganites are described

Electronic Structure of GdCuGe Intermetallic Compound

Science.gov (United States)

Lukoyanov, A. V.; Knyazev, Yu. V.; Kuz'min, Yu. I.

2018-04-01

The electronic structure of GdCuGe intermetallic compound has been studied. Spin-polarized energy spectrum calculations have been performed by the band method with allowance for strong electron correlations in the 4 f-shell of gadolinium ions. Antiferromagnetic ordering of GdCuGe at low temperatures has been obtained in a theoretical calculation, with the value of the effective magnetic moment of gadolinium ions reproduced in fair agreement with experimental data. The electronic density of states has been analyzed. An optical conductivity spectrum has been calculated for GdCuGe; it reveals specific features that are analogous to the ones discovered previously in the GdCuSi compound with a similar hexagonal structure.

Phase transformation and morphology of the intermetallic compounds formed at the Sn-9Zn-3.5Ag/Cu interface in aging

Energy Technology Data Exchange (ETDEWEB)

Hon, M.-H. [Department of Materials Science and Engineering, National Cheng Kung University, 1 Ta-Hsueh Road, Tainan 70101, Taiwan (China); Chang, T.-C. [Department of Materials Science and Engineering, National Cheng Kung University, 1 Ta-Hsueh Road, Tainan 70101, Taiwan (China); Electronic and Optoelectronics Research Laboratories, Industrial Technology Research Institute, Bldg. 11, 195, Sec. 4, Chung-Hsing Road, Chutung, Hsinchu, 310, Taiwan (China); Wang, M.-C. [Faculty of Fragrance and Cosmetics, Kaohsiung Medical University, 100 Shi-Chuan 1st Road, Kaohsiung 807, Taiwan (China)], E-mail: mcwang@kmu.edu.tw

2008-06-30

The morphology and phase transformation of the intermetallic compounds (IMCs) formed at the Sn-9Zn-3.5Ag/Cu interface in a solid-state reaction have been investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), electron diffraction (ED), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). The monoclinic {eta}'-Cu{sub 6}Sn{sub 5} transforms to the hexagonal {eta}-Cu{sub 6}Sn{sub 5} and the orthorhombic Cu{sub 5}Zn{sub 8} transforms to the body-centered cubic (bcc) {gamma}-Cu{sub 5}Zn{sub 8} as aged at 180 deg. C. The scallop-shaped Cu{sub 6}Sn{sub 5} layer is retained after aging at 180 deg. C for 1000 h. In the solid-state reaction, Ag is repelled from {eta}'-Cu{sub 6}Sn{sub 5} and reacts with Sn to form Ag{sub 3}Sn, and the Cu{sub 5}Zn{sub 8} layer decomposes. Kirkendall voids are not observed at the Sn-9Zn-3.5Ag/Cu interface even after aging at 180 deg. C for 1000 h.

Mechanism of forming interfacial intermetallic compounds at interface for solid state diffusion bonding of dissimilar materials

International Nuclear Information System (INIS)

He, P.; Liu, D.

2006-01-01

The formation of brittle intermetallic compounds at the interfaces of diffusion bonds is the main cause which leads to poor bond strength. Therefore, it is very important to study and establish the formation and growth model of intermetallic compounds at the interfaces for the control process of diffusion bonding. In this paper, according to the diffusion kinetics and the thermodynamics, the principle of formation of intermetallic compounds at interfaces in the multi-component diffusion couple, the flux-energy principle, is put forward. In the light of diffusion theory, the formation capacity of the phase at the interfaces is determined by specific properties of the composition in the diffusion couple and the composition ratio of the formed phase is in agreement with the diffusion flux. In accordance with the flux-energy principle, the microstructure of the Ni/TC4 interface is Ni/TiNi 3 /TiNi/Ti 2 Ni/TC4, the microstructure of the TC4/00Cr18Ni9Ti interface is 00Cr18Ni9Ti/TiFe 2 /TiFe/Ti 2 Fe/TC4, and the microstructure of the TiAl/40Cr interface is 40Cr/TiC/Ti 3 Al + FeAl + FeAl 2 /TiAl. Multi-intermetallic compounds with the equivalent flux-energy can be formed at the interfaces at the same time

Thermal stress effects in intermetallic matrix composites

Science.gov (United States)

Wright, P. K.; Sensmeier, M. D.; Kupperman, D. S.; Wadley, H. N. G.

1993-01-01

Intermetallic matrix composites develop residual stresses from the large thermal expansion mismatch (delta-alpha) between the fibers and matrix. This work was undertaken to: establish improved techniques to measure these thermal stresses in IMC's; determine residual stresses in a variety of IMC systems by experiments and modeling; and, determine the effect of residual stresses on selected mechanical properties of an IMC. X ray diffraction (XRD), neutron diffraction (ND), synchrotron XRD (SXRD), and ultrasonics (US) techniques for measuring thermal stresses in IMC were examined and ND was selected as the most promising technique. ND was demonstrated on a variety of IMC systems encompassing Ti- and Ni-base matrices, SiC, W, and Al2O3 fibers, and different fiber fractions (Vf). Experimental results on these systems agreed with predictions of a concentric cylinder model. In SiC/Ti-base systems, little yielding was found and stresses were controlled primarily by delta-alpha and Vf. In Ni-base matrix systems, yield strength of the matrix and Vf controlled stress levels. The longitudinal residual stresses in SCS-6/Ti-24Al-llNb composite were modified by thermomechanical processing. Increasing residual stress decreased ultimate tensile strength in agreement with model predictions. Fiber pushout strength showed an unexpected inverse correlation with residual stress. In-plane shear yield strength showed no dependence on residual stress. Higher levels of residual tension led to higher fatigue crack growth rates, as suggested by matrix mean stress effects.

The corrosion behavior of the T1 (Al2CuLi) intermetallic compound in aqueous environments

Science.gov (United States)

Buchheit, R. G.; Stoner, G. E.

1989-01-01

The intermetallic compound T1 (Al2CuLi) is suspected to play an important role in the localized corrosion at subgrain boundaries in Al-Li-Cu alloys. The intermetallic was synthesized for characterization of its corrosion behavior. Experiments performed included open circuit potential measurements, potentiodynamic polarization, and corrosion rate vs. pH in solutions whose pH was varied over the range of 3 to 11. Subgrain boundary pitting and continuous subgrain boundary corrosion are discussed in terms of the data obtained. Evidence suggesting the dealloying of copper from this compound is also presented.

Effect of solder bump size on interfacial reactions during soldering between Pb-free solder and Cu and Ni/ Pd/ Au surface finishes

International Nuclear Information System (INIS)

NorAkmal, F.; Ourdjini, A.; Azmah Hanim, M.A.; Siti Aisha, I.; Chin, Y.T.

2007-01-01

Flip chip technology provides the ultimate in high I/ O-density and count with superior electrical performance for interconnecting electronic components. Therefore, the study of the intermetallic compounds was conducted to investigate the effect of solder bumps sizes on several surface finishes which are copper and Electroless Nickel/ Electroless Palladium/ Immersion Gold (ENEPIG) which is widely used in electronics packaging as surface finish for flip-chip application nowadays. In this research, field emission scanning electron microscopy (FESEM) analysis was conducted to analyze the morphology and composition of intermetallic compounds (IMCs) formed at the interface between the solder and UBM. The IMCs between the SAC lead-free solder with Cu surface finish after reflow were mainly (Cu, Ni) 6 Sn 5 and Cu 6 Sn 5 . While the main IMCs formed between lead-free solder on ENEPIG surface finish are (Ni, Cu) 3 Sn 4 and Ni 3 Sn 4 . The results from FESEM with energy dispersive x-ray (EDX) have revealed that isothermal aging at 150 degree Celsius has caused the thickening and coarsening of IMCs as well as changing them into more spherical shape. The thickness of the intermetallic compounds in both finishes investigated was found to be higher in solders with smaller bump size. From the experimental results, it also appears that the growth rate of IMCs is higher when soldering on copper compared to ENEPIG finish. Besides that, the results also showed that the thickness of intermetallic compounds was found to be proportional to isothermal aging duration. (author)

Four-branched compounds coupled Si and iron-rich intermetallics in near eutectic Al-Si alloys

International Nuclear Information System (INIS)

Wu, Yuying; Liu, Xiangfa; Jiang, Binggang; Bian, Xiufang

2007-01-01

Many four-branched compounds coupled Si and iron-rich intermetallics were observed in near eutectic Al-Si alloy modified with Al-P master alloy. Such four-branched compounds have never been reported before, but in our case it seems to be commonly observed. In this work the growth characterization of the four-branched compounds are scrutinized with a JXA-8800 electron microprobe (EPMA). More deep study of the formation of four-branched compounds is performed by SEM and TEM analysis. The characterization of the four-branched compounds is that of a primary silicon in the center with four iron-rich intermetallics around. Experimental results also show that the precipitation of primary silicon is the key factor for the formation of four-branched compounds. And WHS-theory explains the growth mechanism of the four-branched compounds. In detail, subsequent twinning within the primary silicon provides four-fold coordination sites on the surface, and then the α-Al(Fe,Mn)-Si phase nucleates on the surface of the primary silicon

Quantifying the dependence of Ni(P) thickness in ultrathin-ENEPIG metallization on the growth of Cu–Sn intermetallic compounds in soldering reaction

Energy Technology Data Exchange (ETDEWEB)

Ho, Cheng-Ying; Duh, Jenq-Gong, E-mail: jgd@mx.nthu.edu.tw

2014-11-14

A new multilayer metallization, ENEPIG (Electroless Ni(P)/Electroless Pd/Immersion Au) with ultrathin Ni(P) deposit (ultrathin-ENEPIG), was designed to be used in high frequency electronic packaging in this study because of its ultra-low electrical impedance. Sequential interfacial microstructures of commercial Sn–3.0Ag–0.5Cu solders reflowed on ultarthin-ENEPIG with Ni(P) deposit thickness ranged from 4.79 μm to 0.05 μm were first investigated. Accelerated thermal aging test was then conducted to evaluate the long-term thermal stabilization of solder joints. The results showed that P-rich intermetallic compound (IMC) layer formed when the Ni(P) thickness was greater than a critical vale (about 0.18 μm). Besides, it is interesting to mention that the growth of (Cu,Ni){sub 6}Sn{sub 5} and (Cu,Ni){sub 3}Sn IMCs was suppressed with the formation of P-rich layer, i.e., Ni{sub 3}P and Ni{sub 2}Sn{sub 1+x}P{sub 1−x} phase, even though the electroless-plated Ni(P) layer was exhausted at initial stage of reflow process. The atomic Cu flux in solder joints without P-rich layer was calculated to be several times larger than that with P-rich layer formation after calculation, which implies that the P-rich layer and ultrathin Ni(P) deposit in ENEPIG served as diffusion barrier against rapid Cu diffusion. - Highlights: • Microstructures in ultrathin-ENEPIG with various Ni(P) thickness are investigated. • P-rich IMC layer formed when the Ni(P) thickness is greater than 0.18 μm. • Secondary (Cu,Ni){sub 6}Sn{sub 5} formed when the Ni(P) thickness is between 0.18 and 0.31 μm. • Cu diffusion flux without P-rich layer is larger than those with P-rich layer. • P-rich layer in ultrathin-ENEPIG exhibits good diffusion barrier characteristic.

NMR and domain wall mobility in intermetallic compounds

International Nuclear Information System (INIS)

Guimaraes, A.P.; Sampaio, L.C.; Cunha, S.F.; Alves, K.M.B.

1991-01-01

The technique of pulsed NMR can be used to study the distribution of hyperfine fields in a magnetic matrix. The dynamics of the domain walls are relevant to the generation of NMR signals. In the present study on the (R x Y 1-x ) Fe 2 intermetallic compounds, the reduction in the signals is associated to increased propagation fields. This indicates that a smaller domain wall mobility is at the origin of these effects. NMR spectra in this system show the importance of direct and indirect (i.e., mediated by Fe atoms) terms in the transferred hyperfine field. (author)

Effects of filling material and laser power on the formation of intermetallic compounds during laser-assisted friction stir butt welding of steel and aluminum alloys

Science.gov (United States)

Fei, Xinjiang; Jin, Xiangzhong; Peng, Nanxiang; Ye, Ying; Wu, Sigen; Dai, Houfu

2016-11-01

In this paper, two kinds of materials, Ni and Zn, are selected as filling material during laser-assisted friction stir butt welding of Q235 steel and 6061-T6 aluminum alloy, and their influences on the formation of intermetallic compounds on the steel/aluminum interface of the joints were first studied. SEM was used to analyze the profile of the intermetallic compound layer and the fractography of tensile fracture surfaces. In addition, EDS was applied to investigate the types of the intermetallic compounds. The results indicate that a thin iron-abundant intermetallic compound layer forms and ductile fracture mode occurs when Ni is added, but a thick aluminum-abundant intermetallic compound layer generates and brittle fracture mode occurs when Zn is added. So the tensile strength of the welds with Ni as filling material is greater than that with Zn as filling material. Besides, the effect of laser power on the formation of intermetallic compound layer when Ni is added was investigated. The preheated temperature field produced by laser beam in the cross section of workpiece was calculated, and the tensile strength of the joints at different laser powers was tested. Results show that only when suitable laser power is adopted, can suitable preheating temperature of the steel reach, then can thin intermetallic compound layer form and high tensile strength of the joints reach. Either excessive or insufficient laser power will reduce the tensile strength of the joints.

Interfacial reaction of Ni{sub 3}Sn{sub 4} intermetallic compound in Ni/SnAg solder/Ni system under thermomigration

Energy Technology Data Exchange (ETDEWEB)

Yang, Yi-Shan; Yang, Chia-Jung; Ouyang, Fan-Yi, E-mail: fyouyang@ess.nthu.edu.tw

2016-07-25

The growth of Ni{sub 3}Sn{sub 4} intermetallic compound (IMC) between liquid–solid interface in micro-scale Ni/SnAg/Ni system was investigated under a temperature gradient of 160 °C/cm at 260 °C on a hot plate. In contrast to a symmetrical growth of Ni{sub 3}Sn{sub 4} on both interfaces under isothermally annealed at 260 °C, the interfacial Ni{sub 3}Sn{sub 4} IMC exhibited asymmetric growth under a temperature gradient; the growth of Ni{sub 3}Sn{sub 4} at cold interface was faster than that at hot side because of temperature gradient induced mass migration of Ni atoms from the hot end toward the cold end. It was found that two-stage growth behavior of Ni{sub 3}Sn{sub 4} IMC under a temperature gradient. A growth model was established and growth kinetic analysis suggested that the chemical potential gradient controlled the growth of Ni{sub 3}Sn{sub 4} at stage I (0–120 min) whereas the dynamic equilibrium between chemical potential gradient and temperature gradient forces was attained at the hot end at stage II (120–210 min). When dynamic equilibrium was achieved at 260 °C, the critical length-temperature gradient product at the hot end was experimentally estimated to be 489.18 μm × °C/cm and the moving velocity of Ni{sub 3}Sn{sub 4} interface due to Ni consumption was calculated to be 0.134 μm/h. The molar heat of transport (Q*) of Ni atoms in molten SnAg solder was calculated to be +0.76 kJ/mol. - Highlights: • Interfacial reaction in Ni/SnAg solder/Ni system under thermal gradient. • Growth rate of Ni{sub 3}Sn{sub 4} at cold end is faster than that at hot end. • Critical length-temperature gradient product at hot end is 489.2 μm°C/cm at 260 °C. • Velocity of Ni{sub 3}Sn{sub 4} moving interface is 0.134 μm/h during dynamic equilibrium. • Molar heat of transport (Q*) of Ni in molten SnAg was +0.76 kJ/mol.

Intermetallic nanoparticles

Science.gov (United States)

Singh, Dileep; Yusufoglu, Yusuf; Timofeeva, Elena; Routbort, Jules

2015-07-14

A process for preparing intermetallic nanoparticles of two or more metals is provided. In particular, the process includes the steps: a) dispersing nanoparticles of a first metal in a solvent to prepare a first metal solution, b) forming a reaction mixture with the first metal solution and a reducing agent, c) heating the reaction mixture to a reaction temperature; and d) adding a second metal solution containing a salt of a second metal to the reaction mixture. During this process, intermetallic nanoparticles, which contain a compound with the first and second metals are formed. The intermetallic nanoparticles with uniform size and a narrow size distribution is also provided. An electrochemical device such as a battery with the intermetallic nanoparticles is also provided.

Development of New Cryocooler Regenerator Materials-Ductile Intermetallic Compounds

International Nuclear Information System (INIS)

Gschneidner, K.A.; Pecharsky, A.O.; Pecharsky, V.K.

2004-01-01

The volumetric heat capacities of a number of binary and ternary Er- and Tm-based intermetallic compounds, which exhibited substantial ductilities, were measured from ∼3 to ∼350 K. They have the RM stoichiometry (where R = Er or Tm, and M is a main group or transition metal) and crystallize in the CsCl-type structure. The heat capacities of the Tm-based compounds are in general larger than the corresponding Er-based materials. Many of them have heat capacities which are significantly larger than those of the low temperature ( 2 , Er 3 Ni and ErNi. Utilization of the new materials as regenerators in the various cryocoolers should improve the performance of these refrigeration units for cooling below 15 K

Process for the manufacture of a superconductor with an intermetallic compound

International Nuclear Information System (INIS)

Wilhelm, M.

1980-01-01

A superconductor with a superconducting intermetallic compound consisting of at least two elements can be manufactured by producing a conductor preproduct with a first component containing one element of the compound and a second component consisting of a carrier metal and the remaining element or elements of the alloy containing the compound, and by heat treating the conductor preproduct, so that the compound is formed by the reaction of the element of the first compound with the remaining element or elements of the second compound. In such a superconductor, one tries to increase the effective current density and critical current. The invention states that the heat treatment should be carried out in a hydrogen atmosphere. Superconductors produced by this process can be used for superconductor devices whose magnetic fields have a flux density above 10 Tesla. (orig.) [de

Magnetic properties of rare-earth intermetallics

International Nuclear Information System (INIS)

Kirchmayr, H.

1978-01-01

A review is given of the concepts at present used to explain the magnetic properties of rare-earth intermetallics which have been the subject of numerous investigations in recent years. Rare-earth intermetallics with the formula Rsub(a)Bsub(b) are divided according to the magnetic moment of the B atom(s). If there is no magnetic moment present at the B-site, the exchange is only between the magnetic moments at the R-sites, which can only be of indirect character. One possible model is still the RKKY model, although it usually gives in practice only a qualitative description of the magnetic properties. Typical R-B compounds with the B-moment equal to zero are (for instance) the RA1 2 compounds, and related compounds such as the RZn and RCd compounds as well as compounds of the general formula RB 2 (B = Ni, Os, Ir, Pd, Ru or Rh). Of all intermetallics with nonzero B-moment, the R-3d intermetallics are the most important. These intermetallics can be formed with Mn, Fe, Co and Ni. In these systems there exist in principle three interactions, namely between the R-R, R-3d and 3d-3d atoms. The most important is usually the latter interaction. After a short discussion of the crystal structures which occur with R-3d intermetallics, the basic magnetic properties of R-3d intermetallics are presented. These properties are discussed with respect to the formation of a magnetic moment at the 3d site in the framework of present band theories. Special emphasis is given to a discussion of the localized or itinerant character of 3d electrons. (author)

A spin echo study of A15 intermetallic compounds

International Nuclear Information System (INIS)

Schoep, G.K.

1976-01-01

This thesis mainly concerns the measurement of spin-lattice relaxation times in intermetallic compounds of the bcc lattice structure, having the formula V 3 X (C = Pt, Ir, Os, Pd, Rh, Ni, Co, Au). When, in a spin echo experiment, a two-pulse sequence was applied, several quadrupolar echoes were observed. Special attention is given to the 'forbidden' echoes (absol.(Δm')GT1) in V 3 Au and V 3 Co. In relation to the V 3 X compounds, several characteristics are discussed including temperature dependence and concentration dependence of spin relaxation times, superconductivity and the importance of d-state electrons in determination of the spin relaxation times. Finally, the above characteristics were determined for 6 different samples of the vanadium-gold alloy, V 3 Au, specifically

Experimental formation enthalpies for intermetallic phases and other inorganic compounds

Science.gov (United States)

Kim, George; Meschel, S. V.; Nash, Philip; Chen, Wei

2017-01-01

The standard enthalpy of formation of a compound is the energy associated with the reaction to form the compound from its component elements. The standard enthalpy of formation is a fundamental thermodynamic property that determines its phase stability, which can be coupled with other thermodynamic data to calculate phase diagrams. Calorimetry provides the only direct method by which the standard enthalpy of formation is experimentally measured. However, the measurement is often a time and energy intensive process. We present a dataset of enthalpies of formation measured by high-temperature calorimetry. The phases measured in this dataset include intermetallic compounds with transition metal and rare-earth elements, metal borides, metal carbides, and metallic silicides. These measurements were collected from over 50 years of calorimetric experiments. The dataset contains 1,276 entries on experimental enthalpy of formation values and structural information. Most of the entries are for binary compounds but ternary and quaternary compounds are being added as they become available. The dataset also contains predictions of enthalpy of formation from first-principles calculations for comparison. PMID:29064466

Pressure effect on magnetic and magnetotransport properties of intermetallic and colossal magnetoresistance oxide compounds

Czech Academy of Sciences Publication Activity Database

Arnold, Zdeněk; Ibarra, M. R.; Algarabel, P. A.; Marquina, C.; De Teresa, J. M.; Morellon, L.; Blasco, J.; Magen, C.; Prokhnenko, Olexandr; Kamarád, Jiří; Ritter, C.

2005-01-01

Roč. 17, - (2005), S3035-S3055 ISSN 0953-8984 Institutional research plan: CEZ:AV0Z10100521 Keywords : pressure effect * intermetallic compounds * magnetic properties * magnetic phase transitions * magnetotransport properties * oxides Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.145, year: 2005

Synthesis and Characterization of Nanocrystalline Ni50Al50-xMox (X=0-5 Intermetallic Compound During Mechanical Alloying Process

Directory of Open Access Journals (Sweden)

A. Khajesarvi

2015-07-01

Full Text Available In the present study, nanocrystalline Ni50Al50-xMox (X = 0, 0.5, 1, 2.5, 5 intermetallic compound was produced through mechanical alloying of nickel, aluminum, and molybdenum powders. AlNi compounds with good and attractive properties such as high melting point, high strength to weight ratio and high corrosion resistance especially at high temperatures have attracted the attention of many researchers. Powders produced from milling were analyzed using scanning electron microscopy (SEM and X-ray diffractometry (XRD. The results showed that intermetallic compound of NiAl formed at different stage of milling operation. It was concluded that at first disordered solid solution of (Ni,Al was formed then it converted into ordered intermetallic compound of NiAl. With increasing the atomic percent of molybdenum, average grain size decreased from 3 to 0.5 μm. Parameter lattice and lattice strain increased with increasing the atomic percent of molybdenum, while the crystal structure became finer up to 10 nm. Also, maximum microhardness was obtained for NiAl49Mo1 alloy.

Diffusion in intermetallic compounds studied using short-lived radioisotopes

CERN Multimedia

Diffusion – the long range movement of atoms – plays an important role in materials processing and in determining suitable applications for materials. Conventional radiotracer methods for measuring diffusion can determine readily how distributions of radioactive probe atoms in samples evolve under varying experimental conditions. It is possible to obtain limited information about atomic jump rates and pathways from these measurements; however, it is desirable to make more direct observations of the atomic jumps by using experimental methods that are sensitive to atomic scale processes. One such method is time-differential perturbed $\\gamma$–$\\gamma$-angular correlation spectroscopy (PAC). Two series of PAC experiments using $^{111m}$Cd are proposed to contribute to fundamental understanding of diffusion in intermetallic compounds. The goal of the first is to determine the dominant vacancy species in several Li$_{2}$-structured compounds and see if the previously observed change in diffusion mechanism th...

Spontaneous growth of whiskers on RE-bearing intermetallic compounds of Sn-RE, In-RE, and Pb-RE

International Nuclear Information System (INIS)

Liu Meng; Xian Aiping

2009-01-01

A phenomenon of the whiskers growth on the bulk rare earth (RE)-intermetallic compounds of NdSn 3 , NdIn 3 , and LaPb 3 is reported. The whiskers formed spontaneously on all of the RE-intermetallic compounds after exposed to room ambience (21-28 deg. C/20-56% RH, relative humidity) for several days. Among the samples, the propensity of whisker growth for NdSn 3 is the strongest, on which the tin whiskers were flourishing and covered all of the surfaces after exposed to room ambience for 22 days; while LaPb 3 is the secondary and NdIn 3 is the last one. Observed by SEM, the whiskers were exhibited as different morphology, size, and number density. The XRD analysis confirms the existence of RE(OH) 3 after whiskers formed, also, the weight gain curve of the samples exposed to room ambience supports that a spontaneous chemical reaction of the RE-intermetallic compounds with water in room ambience takes place. In discussion, it is proposed that the fresh metal atoms released by the chemical reaction could be causative to result in nucleation and spontaneous growth of the whiskers, while the anisotropy of crystal structure could be a reason to understand the difference of the whisker growth behaviors between Sn and Pb.

Magnetic and electronic properties of some actinide intermetallic compounds

International Nuclear Information System (INIS)

Yaar, Ilan

1992-06-01

The electronic structure and magnetic properties of the light actinide intermetallic compounds are often related to interplay between localized and itinerant (band like) behavior of the 5f- electrons. In the present work, the properties of some actinide, mainly Np, intermetallic compounds were studied by Mossbauer effect, ac and dc susceptibility, X-ray and Neutron diffraction techniques. 1. NpX 2 (X=Ga,Si) - Both compounds order ferromagnetically at TC=55(2) and 48(2) K respectively. A comparison of our data with the results for other NpX 2 (X=Al,As,Sb,Tl) compounds indicates that NpGa 2 is a highly localized 5f electron system, whereas in NpSi 2 the 5f electrons are partially delocalized. The magnetic properties of NpX 2 compounds can neither be consistently explained within the conventional crystal electric field picture (CEF) nor by takink into account hybridization dressing of local spin density models. 2. NpX 3 (X=Ga,Si,In,Al) in the cubic AuCu 3 (Pm3m) crystallographic structure - From the Mossbauer isomer shift (IS) data we argue that the Np ion in the NpX 3 family is close to the formal 3+ (5I 4 ) charge state. The magnetic moment of the Np in NpSi 3 is totally suppressed whereas in NpGa 3 and NpAl 3 a localized (narrow band) moment is established. However, in NpIn 3 at 4.2 K, a modulated magnetic moment (0-1.5μB) is observed. Comparing the magnetic behavior of the NpX 3 family (X=Si,Ge,Ga, Al,In and Sn), we find an impressive variation of the magnetic properties, from temperature independent paramagnetism (TIP), localized and modulated ordered moments, to the formation of a concentrated Kondo lattice. Hybridization of 5f electrons with ligand electrons appears to play a crucial role in establishing these magnetic properties. However, at present a consistent theoretical picture can not be drawn. 3. XFe 4 Al 8 (X=Ho,Np,U) spin galss (SG) systems in the ThMn 12 (I 4 /mmm) crystallographic structure - Localized and itinerant behaviour of the f electrons

PDSS/IMC requirements and functional specifications

Science.gov (United States)

1983-01-01

The system (software and hardware) requirements for the Payload Development Support System (PDSS)/Image Motion Compensator (IMC) are provided. The PDSS/IMC system provides the capability for performing Image Motion Compensator Electronics (IMCE) flight software test, checkout, and verification and provides the capability for monitoring the IMC flight computer system during qualification testing for fault detection and fault isolation.

Characterization of intermetallic compounds in Cu-Al ball bonds: layer growth, mechanical properties and oxidation

NARCIS (Netherlands)

Kouters, M.H.M.; Gubbels, G.H.M.; O'Halloran, O.; Rongen, R.

2011-01-01

In high power automotive electronics copper wire bonding is regarded as most promising alternative for gold wire bonding in 1 st level interconnects and therefore subjected to severe functional requirements. In the Cu-Al ball bond interface the growth of intermetallic compounds may deteriorate the

Properties of vacancies type defects in intermetallic compounds of the Al-Mo system

International Nuclear Information System (INIS)

Pascuet, M.I; Fernandez, J.R; Monti, A.M

2006-01-01

There are five intermetallic compounds in the Al-Mo system that are stable at low temperatures. Of these, the richest phases in some of the two components are the compounds Al 12 Mo and AlMo 3 , whose Pearson symbols are cI26 and cP8, respectively. In both structures, the atoms of the minority component occupy positions bcc and each one of them is surrounded by 12 atoms first neighbors of the other component. These 13 atoms form icosahedron shaped units or heaps. Unlike what occurs in Al 12 Mo, the AlMo 3 heaps are superposed by sharing atoms from the majority component. The neighboring environment of the majority component is mixed but differs considerably in one or another intermetallic. In each structure, the sites occupied by any given species are crystallographically equivalent, that is, they can self generate from one of the positions and from the crystalline structure's elements of symmetry. This work studies the energy of vacancies and antisites in both compounds and the atomic-jump processes to vacant sites. Computer simulation techniques were used based on minimizing the system's energy. Many-body embedded-atom potentials were used to represent the atomic interactions. The potential mixture used resulted in an adjustment to the crystalline structure of the AlMo 3 phase at low temperatures and to its formation energy (cw)

Spontaneous growth of whiskers on RE-bearing intermetallic compounds of Sn-RE, In-RE, and Pb-RE

Energy Technology Data Exchange (ETDEWEB)

Liu Meng [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Science, 72 Wenhua Road, Shenyang 110016 (China); Xian Aiping, E-mail: ap.xian@imr.ac.c [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Science, 72 Wenhua Road, Shenyang 110016 (China)

2009-11-03

A phenomenon of the whiskers growth on the bulk rare earth (RE)-intermetallic compounds of NdSn{sub 3}, NdIn{sub 3}, and LaPb{sub 3} is reported. The whiskers formed spontaneously on all of the RE-intermetallic compounds after exposed to room ambience (21-28 deg. C/20-56% RH, relative humidity) for several days. Among the samples, the propensity of whisker growth for NdSn{sub 3} is the strongest, on which the tin whiskers were flourishing and covered all of the surfaces after exposed to room ambience for 22 days; while LaPb{sub 3} is the secondary and NdIn{sub 3} is the last one. Observed by SEM, the whiskers were exhibited as different morphology, size, and number density. The XRD analysis confirms the existence of RE(OH){sub 3} after whiskers formed, also, the weight gain curve of the samples exposed to room ambience supports that a spontaneous chemical reaction of the RE-intermetallic compounds with water in room ambience takes place. In discussion, it is proposed that the fresh metal atoms released by the chemical reaction could be causative to result in nucleation and spontaneous growth of the whiskers, while the anisotropy of crystal structure could be a reason to understand the difference of the whisker growth behaviors between Sn and Pb.

Determination of the enthalpy of formation of Ni-Al intermetallic compounds using differential scanning calorimetry technique

International Nuclear Information System (INIS)

Kubaski, Evaldo Toniolo; Capocchi, Jose Deodoro Trani; Cintho, Osvaldo Mitsuyuki

2010-01-01

The compositions Ni20Al80, Ni25Al75, Ni40Al60, Ni50Al50, Ni60Al40 and Ni75Al25 (at. %) were heated in a calibrated thermal analysis equipment. All runs were conducted at a heating rate of 10 deg C/min under a dynamic argon atmosphere. Each composition was heated until the completion of the corresponding exothermic reaction responsible for intermetallic compound formation, and, also heated to 1480 deg C. The products obtained were characterized using X ray diffraction in order to identify the intermetallic compounds that were synthesized. Moreover, the results were evaluated using variance analysis. As a result, enthalpies of formation of Ni 2 Al 3 and Ni 3 Al compounds were determined by means of this methodology. Experimental values were 167 kJ/mol and 93 kJ/mol for Ni 2 Al 3 and Ni 3 Al, respectively. The former is 18% lower than the value found on literature, while the latter is 6% greater. (author)

B2 intermetallic compounds of Zr. New class of the shape memory alloys

International Nuclear Information System (INIS)

Koval, Yu.N.; Delaey, L.; Jang, W.Y.

1995-01-01

It is known that the B2 equiatomic intermetallic compounds of Zr (ZrCo-based) undergo a martensitic transformation (MT) with wide temperature hysteresis. It was found that the MT is accompanied by the perfect shape memory effect (SME) for ZrCu and ZrRh. In this report we represent the results of structural analysis, electrical resistivity, calorimetric and SME measurements for ZrCu- and ZrCo-based compounds. Interrelation between structural, thermodynamical parameters of MT and SME in this alloys will be described. The shape memory aspects of this potential alloys for the application at high temperatures will be discussed. (orig.)

Characterization of intermetallic compounds in Cu-Al ball bonds: thermo-mechanical properties, interface delamination and corrosion

NARCIS (Netherlands)

Gubbels, G.H.M.; Kouters, M.H.M.; Dos Santos Ferreira, O.

2012-01-01

In high power automotive electronics copper wire bonding is regarded as the most promising alternative for gold wire bonding in 1st level interconnects. In the Cu-Al ball bond interface the growth of intermetallic compounds can deteriorate the electrical and mechanical properties of the

Effect of Intermetallic on Electromigration and Atomic Diffusion in Cu/SnAg3.0Cu0.5/Cu Joints: Experimental and First-Principles Study

Science.gov (United States)

Zhou, Wei; Liu, Lijuan; Li, Baoling; Wu, Ping

2009-06-01

Electromigration phenomena in a one-dimensional Cu/SnAg3.0Cu0.5/Cu joint were investigated with current stressing. The special effect of intermetallic compound (IMC) layers on the formation of serious electromigration damage induced by nonuniform current density distribution was discussed based on experimental results. Meanwhile, hillocks were observed both at the anode and near the cathode of the joint, and they were described as the result of diffusion of atoms and compressive stress released along grain boundaries to the relatively free surface. Moreover, the diffusion behavior of Cu at the cathode was analyzed with the electromigration equation, and the stability of Ag atoms in the solder during electromigration was evaluated with a first-principles method.

Reaction of intermetallic compounds of the ScT composition (T=Ag, Cu, Zn, Ni) with hydrogen

International Nuclear Information System (INIS)

Shilkin, S.P.; Volkova, L.S.; Tarasov, B.P.

1995-01-01

Reaction of intermetallic compounds of ScT composition (T=Ag, Cu, Zn, Ni), crystallized in CsCl structural type, with hydrogen at 0.2-10 MPa pressure and 293-673 K temperature is studied by chemical, x-ray phase and complex thermogravimetry analysis methods. It is shown that under such conditions hydrogen absorption by ScAg and ScCu is accompanied by the decay of their source matrices into scandium dihydride and metal silver and copper respectively. For ScZn a fine-dispersion mixture of scandium dihydride with zinc and hydride phase of a new zinc-containing intermetallic compound appears to be the finite reaction product. In case of ScNi a hydride phase of ScNiH 2.6 composition is produced, which is crystallized in a rhombic syngony with the lattice periods: a=0.5281±0.0007, b=0.7393±0.0009 and c=0.3327±0.0004 nm. 9 refs.; 2 tabs

Thermodynamic data for uranium and thorium intermetallic compounds: A historical perspective

International Nuclear Information System (INIS)

Alcock, C.B.

1989-01-01

The development of quantitative information concerning the stabilities of uranium and thorium intermetallic compounds since the publication of Rough and Bauer's phase diagram compilation are reviewed. During this era a number of high temperature measurement techniques have been developed, from gas/solid equilibration to mass spectrometry and from high temperature calorimetry to solid state electrochemistry, and the growth of quantitative information has run parallel to this evolution. The amount of experimental effort now appears to be declining, and the task presently of major importance is to integrate and rationalize the quantitative information, an effort which will undoubtedly lead to new experimental initiatives. (orig.)

Structure evolution of multilayer materials of heat-resistant intermetallic compounds under the influence of temperature in the process of diffusion welding under pressure and their mechanical properties

Energy Technology Data Exchange (ETDEWEB)

Korzhov, Valeriy P.; Karpov, Michael I.; Prokhorov, Dmitriy V. [Institute of Solid State Physics, Russian Academy of Sciences, Chernogolovka (Russian Federation)

2013-07-01

Multilayer materials of high-resistant intermetallic compounds of some transition metals with aluminum and silicon were obtained by diffusion welding of packages, collected from a large number of the respective foils, such as niobium and aluminum. Materials of intermetallics with silicon were obtained by the welding of packages built from metal foils with Si-coating. The change in the structure according to the temperature of the welding was studied, and the high-temperature bending strength was determined. Key words: multilayer composite, high-resistant material, intermetallic compound, diffusion welding, package rolling, layered structure, bending strength.

Effects of elastic anisotropy on mechanical behavior of intermetallic compounds

International Nuclear Information System (INIS)

Yoo, M.H.

1991-01-01

Fundamental aspects of the deformation and fracture behavior of ordered intermetallic compounds are examined within the framework of linear anisotropic elasticity theory of dislocations and cracks. The orientation dependence and the tension/compression asymmetry of yield stress are explained in terms of the anisotropic coupling effect of non-glide stresses to the glide strain. The anomalous yield behavior is related to the disparity (edge/screw) of dislocation mobility and the critical stress required for the dislocation multiplication mechanism of Frank-Read type. The slip-twin conjugate relationship, extensive faulting, and pseudo-twinning (martensitic transformation) at a crack tip can be enhanced also by the anisotropic coupling effect, which may lead to transformation toughening of shear type

On the valence state of Yb and Ce in transition metal intermetallic compounds

International Nuclear Information System (INIS)

Boer, F.R. de; Dijkman, W.H.; Mattens, W.C.M.

1979-01-01

In the pure state Yb is a divalent metal, similar to Ca; in alloys it can become trivalent like the majority of the rare earth metals. Using a value of 38 kJ (mol Yb) -1 for the energy difference between divalent and trivalent Yb metal and using model calculations for the heat of formation of intermetallic compounds, the authors are able to account for the existing information on the valence state of Yb in transition metal compounds. A similar analysis of compounds of Ce with transition metals shows that a model in which the 4f electron is treated as a core electron, i.e. being absent in the tetravalent modification of Ce and present as a fully localized electron in trivalent Ce, does not apply. (Auth.)

Pathway analysis of IMC

DEFF Research Database (Denmark)

Skrypnyuk, Nataliya; Nielson, Flemming; Pilegaard, Henrik

2009-01-01

We present the ongoing work on the pathway analysis of a stochastic calculus. Firstly we present a particular stochastic calculus that we have chosen for our modeling - the Interactive Markov Chains calculus, IMC for short. After that we specify a few restrictions that we have introduced into the...... into the syntax of IMC in order to make our analysis feasible. Finally we describe the analysis itself together with several theoretical results that we have proved for it.......We present the ongoing work on the pathway analysis of a stochastic calculus. Firstly we present a particular stochastic calculus that we have chosen for our modeling - the Interactive Markov Chains calculus, IMC for short. After that we specify a few restrictions that we have introduced...

Contribution to the study of magnetic properties of rare-earth iron intermetallic compounds

International Nuclear Information System (INIS)

Morariu, M.

1976-01-01

The intermetallic binary compounds Ysub(x)Fesub(y)(YFe 2 ,YFe 3 ,Y 6 Fe 23 ,Y 2 Fe 17 ), RFe 2 (R=Gd,Tb,Dy,Ho,Er and Tm) and the intermetallic pseudobinary compounds (Gdsub(x)Ysub(1-x))Fe 2 and Dy(Fesub(x)Nisub(1-x)) 3 were studied, using magnetic measurements and Moessbauer spectroscopy, in order to obtain information on their magnetic behaviour. The different models which describe magnetic interactions in rare-earths with 3d transition element compounds are reviewed. The magnetic hyperfine field Hsub(n) at the Fe 57 nucleus, measured by Moessbauer spectroscopy, depends on the atom position in the lattice, being sensitive to magnetic interactions with neighbouring atoms. The mean value of the magnetic hyperfine field, average Hsub(n) is proportional to the mean magnetic moment of the iron atom: average Hsub(n)/average μsub(Fe) approximately 150 kOe. The comparative study of the temperature dependence of average Hsub(n) and average μsub(Fe) values shows that this relation is valid for the whole range of magnetic ordering (T>Tsub(c)). The mean magnetic hyperfine fields at the Fe 57 nucleus in RFe 2 compounds depend on the rare-earth partner and vary approximative linearly with the Gennes factor. The spin reorientation diagram for the (Gdsub(x)Ysub(1-x))Fe 2 system is obtained. All results on Moessbauer spectroscopy are in good agreement with the magnetic measurements. The magnetic behaviour of iron atoms is justified using a model in which the most electrons are in a narrow band, so they could be considered localized, and the magnetic interactions between these atoms take place through a fraction (<5%) of 3d itinerant electrons. (author)

Vacuum brazing of TiAl48Cr2Nb2 casting alloys based on TiAl (γ intermetallic compound

Directory of Open Access Journals (Sweden)

Z. Mirski

2010-01-01

Full Text Available A growing interest in modern engineering materials characterised by increasingly better operational parameters combined with a necessity to obtain joints of such materials representing good operation properties create important research and technological problems of today. These issues include also titanium joints or joints of titanium alloys based on intermetallic compounds. Brazing is one of the basic and sometimes even the only available welding method used for joining the aforesaid materials in production of various systems, heat exchangers and, in case of titanium alloys based on intermetallic compounds, turbine elements and space shuttle plating etc. This article presents the basic physical and chemical properties as well as the brazability of alloys based on intermetallic compounds. The work also describes the principle and mechanisms of diffusion-brazed joint formation as well as reveals the results of metallographic and strength tests involving diffusion-welded joints of TiAl48Cr3Nb2 casting alloy based on TiAl (γ phase with the use of sandwich-type layers of silver-based parent metal (grade B- Ag72Cu-780 (AG 401 and copper (grade CF032A. Structural examination was performed by means of light microscopy, scanning electron microscope (SEM and energy dispersion spectrometer (EDS. Furthermore, the article reveals the results of shear strength tests involving the aforementioned joints.

Mictomagnetic, ferromagnetic, and antiferromagnetic transitions in La(FexAl1–x)13 intermetallic compounds

NARCIS (Netherlands)

Palstra, T.T.M.; Nieuwenhuys, G.J.; Mydosh, J.A.; Buschow, K.H.J.

1985-01-01

Cubic La(FexAl1–x)13 intermetallic compounds can be stabilized with iron concentration x between 0.46 and 0.92 in the NaZn13-type structure (D23) with Fm3c (Oh6) space-group symmetry. Here the Fe-Fe coordination number can increase up to 12. At low x values, a mictomagnetic regime occurs with

Electronic and magnetic properties of intermetallic compound YCo5

International Nuclear Information System (INIS)

Zhang, G.W.; Feng, Y.P.; Ong, C.K.

1998-01-01

The electronic and magnetic properties of the intermetallic compound YCo 5 have been studied using density functional theory with the local spin density approximation. The calculated magnetic moments of Y, Co(2c) and Co(3g) are -0.61, 1.68 and 2.04 μ B , respectively, and the total magnetic moment is about 8.87 μ B per formula unit, which agrees well with the previous experimental results. The dependence of the magnetic moments of Y, Co(2c) and Co(3g) on the lattice spacing has been investigated. The local electronic structure of Y, Co(2c) and Co(3g) are discussed in detail. The local magnetic susceptibilities of Y, Co(2c) and Co(3g) are calculated. Based on our results, YCo 5 was found to have characteristic of a strong ferromagnet. (orig.)

The intermetallic ThRh5: microstructure and enthalpy increments

International Nuclear Information System (INIS)

Banerjee, Aparna; Joshi, A.R.; Kaity, Santu; Mishra, R.; Roy, S.B.

2013-01-01

Actinide intermetallics are one of the most interesting and important series of compounds. Thermochemistry of these compounds play significant role in understand the nature of bonding in alloys and nuclear fuel performance. In the present paper we report synthesis and characterization of thorium based intermetallic compound ThRh 5 (s) by SEM/EDX technique. The mechanical properties and enthalpy increment as a function of temperature of the alloy has been measured. (author)

Microstructural evolution of Ni40Zr60 alloy during early stage of mechanical alloying of intermetallic compounds NiZr2 and Ni11Zr9

International Nuclear Information System (INIS)

Lee Peeyew; Koch, C.C.

1994-01-01

The microstructural change of Ni 40 Zr 60 alloy during mechanical alloying of mixtures of the intermetallic compounds NiZr 2 and Ni 11 Zr 9 has been studied by transmission electron microscopy. A specific ''cauliflower'' phase was formed during early stage of mechanical alloying process. It is suggested that the solid state reaction between intermetallic compounds NiZr 2 and Ni 11 Zr 9 is not the only origin for the formation of the ''cauliflower'' phase. ((orig.))

Nucleation and Growth of Cu-Al Intermetallics in Al-Modified Sn-Cu and Sn-Ag-Cu Lead-Free Solder Alloys

Science.gov (United States)

Reeve, Kathlene N.; Anderson, Iver E.; Handwerker, Carol A.

2015-03-01

Lead-free solder alloys Sn-Cu (SC) and Sn-Ag-Cu (SAC) are widely used by the microelectronics industry, but enhanced control of the microstructure is needed to improve solder performance. For such control, nucleation and stability of Cu-Al intermetallic compound (IMC) solidification catalysts were investigated by variation of the Cu (0.7-3.0 wt.%) and Al (0.0-0.4 wt.%) content of SC + Al and SAC + Al alloys, and of SAC + Al ball-grid array (BGA) solder joints. All of the Al-modified alloys produced Cu-Al IMC particles with different morphologies and phases (occasionally non-equilibrium phases). A trend of increasing Cu-Al IMC volume fraction with increasing Al content was established. Because of solidification of non-equilibrium phases in wire alloy structures, differential scanning calorimetry (DSC) experiments revealed delayed, non-equilibrium melting at high temperatures related to quenched-in Cu-Al phases; a final liquidus of 960-1200°C was recorded. During cooling from 1200°C, the DSC samples had the solidification behavior expected from thermodynamic equilibrium calculations. Solidification of the ternary alloys commenced with formation of ternary β and Cu-Al δ phases at 450-550°C; this was followed by β-Sn, and, finally, Cu6Sn5 and Cu-Al γ1. Because of the presence of the retained, high-temperature phases in the alloys, particle size and volume fraction of the room temperature Cu-Al IMC phases were observed to increase when the alloy casting temperature was reduced from 1200°C to 800°C, even though both temperatures are above the calculated liquidus temperature of the alloys. Preliminary electron backscatter diffraction results seemed to show Sn grain refinement in the SAC + Al BGA alloy.

Description of structure of Fe-Zn intermetalic compounds present in hot-dip galvanized coatings on steel

Directory of Open Access Journals (Sweden)

P. Pokorny

2015-10-01

Full Text Available The article is describing formation, composition, morphology and crystallographic characteristics of intermetalic compounds Fe - Zn present in the coating formed during the process of low-temperature hot-dip galvanizing of carbon steels. In mutual confrontation we introduce older bibliography and results of latest modern researches based on combination of most precise analytical methods.

Valence behavior of Eu-ions in intermetallic compound Ce{sub 0.5}Eu{sub 0.5}Pd{sub 3}B{sub 0.5}

Energy Technology Data Exchange (ETDEWEB)

Pandey, Abhishek, E-mail: apandey@ameslab.gov [Experimental Condensed Matter Physics Division, Saha Institute of Nuclear Physics, 1/AF, Bidhannagar, Kolkata 700064 (India); S.N. Bose National Centre for Basic Sciences, Block-JD, Sector-III, Salt Lake, Kolkata 700098 (India); Mazumdar, Chandan, E-mail: chandan.mazumdar@saha.ac.in [S.N. Bose National Centre for Basic Sciences, Block-JD, Sector-III, Salt Lake, Kolkata 700098 (India); Ranganathan, R. [S.N. Bose National Centre for Basic Sciences, Block-JD, Sector-III, Salt Lake, Kolkata 700098 (India); Raghavendra Reddy, V.; Gupta, Ajay [UGC-DAE Consortium for Scientific Research, University Campus, Khandawa Road, Indore (India)

2011-12-15

We have studied the valence behavior of rare-earth ions, in particular Eu-ions, in a cubic intermetallic compound Ce{sub 0.5}Eu{sub 0.5}Pd{sub 3}B{sub 0.5} which is a homogeneous solid solution of two mixed-valent compounds CePd{sub 3} and EuPd{sub 3}B. Results of {sup 151}Eu Moessbauer spectroscopic measurements show that two different valence states, i.e., divalent- and trivalent-like states of Eu-ions exist in the compound. The possible reason for the observed heterogeneous valency vis-a-vis the variation in the chemical environment and the number of nearest-neighbor B atoms surrounding the Eu-ions has been discussed. Our results demonstrate that B incorporation in such Eu-based cubic intermetallic compounds leads to a situation where heterogeneous-valence state of Eu-ions is an energetically favorable ground state. - Highlights: > Intermetallic compound Ce{sub 0.5}Eu{sub 0.5}Pd{sub 3}B{sub 0.5} crystallizes in a single phase. > Eu-ions in Ce{sub 0.5}Eu{sub 0.5}Pd{sub 3}B{sub 0.5} are charge-ordered compared to +2.3 valency in Ce{sub 0.5}Eu{sub 0.5}Pd{sub 3}. > B incorporation makes charge-ordered state of Eu-ions energetically more favorable. > Nearest-neighbor chemical environment affects the Eu valency.

Phase transformations in intermetallic phases in zirconium alloys

Energy Technology Data Exchange (ETDEWEB)

Filippov, V. P., E-mail: vpfilippov@mephi.ru [National Research Nuclear University MEPhI (Moscow Engineering Physics Institute) (Russian Federation); Kirichenko, V. G. [Kharkiv National Karazin University (Ukraine); Salomasov, V. A. [National Research Nuclear University MEPhI (Moscow Engineering Physics Institute) (Russian Federation); Khasanov, A. M. [University of North Carolina – Asheville, Chemistry Department (United States)

2017-11-15

Phase change was analyzed in intermetallic compounds of zirconium alloys (Zr – 1.03 at.% Fe; Zr – 0.51 at.% Fe; Zr – 0.51 at.% Fe – M(M = Nb, Sn). Mössbauer spectroscopy on {sup 57}Fe nuclei in backscattering geometry with the registration of the internal conversion electrons and XRD were used. Four types of iron bearing intermetallic compounds with Nb were detected. A relationship was found between the growth process of intermetallic inclusions and segregation of these phases. The growth kinetics of inclusions possibly is not controlled by bulk diffusion, and a lower value of the iron atom’s activation energy of migration can be attributed to the existence of enhanced diffusion paths and interface boundaries.

FY 1992 Report on the survey results. Surveys on trends of research and development of advanced materials for severe environments (Intermetallic compounds); 1992 nendo chotaikankyosei senshin zairyo no kenkyu kaihatsu (kinzokukan kagobutsu) ni kakawaru kenkyu doko chosa

Energy Technology Data Exchange (ETDEWEB)

NONE

1993-03-01

The trends of the ongoing researches on intermetallic compounds are surveyed through interviews and inquiries, in order to evaluate the results of the projects and research and development of the advanced materials for severe environments, and also to survey the research trends. The survey results are pigeonholed into 4 general categories; (1) research trends in the USA, UK and Germany, (2) notable topics of recent progress in intermetallic research and development, (3) evaluation of the projects, and (4) lists of the results of the researches on the Al-Ti and Al-Nb intermetallic compounds. The ongoing projects include those for intermetallic compounds of high specific strength and of high melting point, the former being represented by Al-Ti compounds and the latter by Al-Nb compounds, for aircraft and space development purposes. The projects are evaluated, viewed from materials and purposes/targets pursued by the projects, R and D organizations, and degree of attention the projects are attracting. The intermetallic compounds are extensively studied and attracting attention in various countries, but possibilities of achieving the set targets are rather pessimistic. (NEDO)

Multi-component intermetallic electrodes for lithium batteries

Science.gov (United States)

Thackeray, Michael M; Trahey, Lynn; Vaughey, John T

2015-03-10

Multi-component intermetallic negative electrodes prepared by electrochemical deposition for non-aqueous lithium cells and batteries are disclosed. More specifically, the invention relates to composite intermetallic electrodes comprising two or more compounds containing metallic or metaloid elements, at least one element of which can react with lithium to form binary, ternary, quaternary or higher order compounds, these compounds being in combination with one or more other metals that are essentially inactive toward lithium and act predominantly, but not necessarily exclusively, to the electronic conductivity of, and as current collection agent for, the electrode. The invention relates more specifically to negative electrode materials that provide an operating potential between 0.05 and 2.0 V vs. metallic lithium.

Influence of Difference Solders Volume on Intermetallic Growth of Sn-4.0Ag-0.5Cu/ENEPIG

Directory of Open Access Journals (Sweden)

Saliza Azlina O.

2016-01-01

Full Text Available In recent years, portable electronic packaging products such as smart phones, tablets, notebooks and other gadgets have been developed with reduced size of component packaging, light weight, high speed and with enhanced performance. Thus, flip chip technology with smaller solder sphere sizes that would produce fine solder joint interconnections have become essential in order to fulfill these miniaturization requirements. This study investigates the interfacial reactions and intermetallics formation during reflow soldering and isothermal aging between Sn-4.0Ag-0.5Cu (SAC405 and electroless nickel/immersion palladium/immersion gold (EN(PEPIG. Solder diameters of 300 μm and 700 μm were used to compare the effect of solder volume on the solder joint microstructure. The solid state isothermal aging was performed at 125°C starting from 250 hours until 2000 hours. The results revealed that only (Cu,Ni6Sn5 IMC was found at the interface during reflow soldering while both (Cu,Ni6Sn5 and (Ni,Cu3Sn4 IMC have been observed after aging process. Smaller solder sizes produced thinner IMC than larger solder joints investigated after reflow soldering, whereas the larger solders produced thinner IMC than the smaller solders after isothermal aging. Aging duration of solder joints has been found to be increase the IMC’s thickness and changed the IMC morphologies to spherical-shaped, compacted and larger grain size.

Ab-initio thermodynamic and elastic properties of AlNi and AlNi3 intermetallic compounds

Science.gov (United States)

Yalameha, Shahram; Vaez, Aminollah

2018-04-01

In this paper, thermodynamic and elastic properties of the AlNi and AlNi3 were investigated using density functional theory (DFT). The full-potential linearized augmented plane-wave (APW) in the framework of the generalized gradient approximation as used as implemented in the Wien2k package. The temperature dependence of thermal expansion coefficient, bulk modulus and heat capacity in a wide range of temperature (0-1600 K) were investigated. The calculated elastic properties of the compounds show that both intermetallic compounds of AlNi and AlNi3 have surprisingly negative Poisson’s ratio (NPR). The results were compared with other experimental and computational data.

A theoretical search for intermetallic compounds and solution phases in the binary system Sn/Zn

Energy Technology Data Exchange (ETDEWEB)

Appen, Joerg von; Dronskowski, Richard; Hack, Klaus

2004-10-06

The binary system Sn/Zn was theoretically investigated by a classical thermodynamic analysis (CALPHAD approach) and by density-functional total-energy calculations on the basis of the LDA/GGA, plane waves/muffin-tin orbitals, and supercell geometries. In harmony with experimental data, both methods agree in that there is only very small solubility between the elements and no formation of a stable intermetallic phase over the entire compositional range. For the hypothetical composition Sn{sub 2}Zn, a total of 30 different crystal structures was quantum-mechanically optimized, and the chemical bondings of Sn{sub 2}Zn adopting the CaF{sub 2} and HgBr{sub 2} structures were analyzed in detail; generally, the more ionic structure types are better suited for the Sn{sub 2}Zn composition than typical intermetallic ones. Theoretical enthalphy-pressure diagrams were generated to explore high-pressure compound formation, and the observed transition pressures between the {alpha}, {beta} and {gamma} allotropes of tin were correctly reproduced by electronic structure theory.

INVESTIGATING THE fFORMATION OF INTERMETALLIC COMPOUNDS AND THE VARIATION OF BOND STRENGTH BETWEEN Al-Cu LAYERS AFTER ANNEALING IN PRESENCE OF NICKEL BETWEEN LAYERS

Directory of Open Access Journals (Sweden)

A. Shabani

2016-06-01

Full Text Available In the present study, the effect of post-rolling annealing heat treatment on the formation of intermetallic compounds between Al-Cu strips, in the presence of nickel coating on the Cu strips, was investigated. In addition, the effect of post-rolling annealing and intermetallic compounds on the bond strength of Al-Cu strips was evaluated. In order to prepare samples, Cu strips were coated with nickel by electroplating process. After surface preparing, Cu strips were placed between two Al strips and roll bonded. This method is used for producing Al-Ni-Cu composites. Then the samples were annealed at 773K for 2 h. The formation of intermetallic compounds was studied using energy dispersive spectroscopy (EDS and X-ray diffraction (XRD. Also, in order to investigate bond strength of Al-Cu after post-rolling annealing heat treatment, samples were produced using nickel powder and nickel coating. Then bond strength of strips was investigated using peeling test. The results revealed that by post-rolling annealing of layers, the bond strength between Al-Cu strips decreases dramatically.

Electrochemical preparation of Al–Sm intermetallic compound whisker in LiCl–KCl Eutectic Melts

International Nuclear Information System (INIS)

Ji, De−Bin; Yan, Yong−De; Zhang, Mi−Lin; Li, Xing; Jing, Xiao−Yan; Han, Wei; Xue, Yun; Zhang, Zhi−Jian; Hartmann, Thomas

2015-01-01

Highlights: • The reduction process of Sm(III) was investigated in LiCl–KCl melt on an aluminum electrode at 773 K. • Al–Sm alloy with different phase structure (Al 2 Sm and Al 3 Sm) was prepared by potentiostatic electrolysis on an aluminum electrode with the change of electrolytic potentials and time in LiCl–KCl–SmCl 3 melts. • Al − Sm alloy containing whiskers (Al 4 Sm) was obtained by potentiostatic electrolysis (−2.10 V) on an aluminum electrode for 7 hours with the change of electrolytic temperature and cooling rate in LiCl–KCl–SmCl 3 (16.5 wt. %) melts. The results from micro–hardness test and potentiodynamic polarization test show the micro hardness and corrosion property are remarkably improved with the help of Al–Sm intermetallic compound whiskers. - Abstract: This work presents the electrochemical study of Sm(III) on an aluminum electrode in LiCl–KCl melts at 773 K by different electrochemical methods. Three electrochemical signals in cyclic voltammetry, square wave voltammetry, open circuit chronopotentiometry, and cathode polarization curve are attributed to different kinds of Al–Sm intermetallic compounds, Al 2 Sm, Al 3 Sm, and Al 4 Sm, respectively. Al–Sm alloy with different phase structure (Al 2 Sm and Al 3 Sm) could be obtained by the potentiostatic electrolysis with the change of electrolytic potentials and time. Al–Sm alloy containing whiskers (Al 4 Sm) was obtained by potentiostatic electrolysis (−2.10 V) on an aluminum electrode for 7 hours with the change of electrolytic temperature and cooling rate in LiCl–KCl–SmCl 3 (16.5 wt. %) melts. The XRD and SEM&EDS were employed to investigate the phase composition and microstructure of Al–Sm alloy. SEM analysis shows that lots of needle−like precipitates formed in Al–Sm alloy, and their ratios of length to diameter are found to be greater than 10 to 1. The TEM and electron diffraction pattern were performed to investigate the crystal structure of the

Characterization of intermetallics in aluminum to zinc coated interstitial free steel joining by pulsed MIG brazing for automotive application

Energy Technology Data Exchange (ETDEWEB)

Basak, Sushovan, E-mail: sushovanbasak@gmail.com [Metallurgical and Material Engineering Department, Jadavpur University, Kolkata–700032 (India); Das, Hrishikesh, E-mail: hrishichem@gmail.com [Metallurgical and Material Engineering Department, Jadavpur University, Kolkata–700032 (India); Pal, Tapan Kumar, E-mail: tkpal.ju@gmail.com [Metallurgical and Material Engineering Department, Jadavpur University, Kolkata–700032 (India); Shome, Mahadev, E-mail: mshome@tatasteel.com [Material Characterization & Joining Group, R & D, Tata Steel, Jamshedpur–831007 (India)

2016-02-15

In order to meet the demand for lighter and more fuel efficient vehicles, a significant attempt is currently being focused toward the substitution of aluminum for steel in the car body structure. It generates vital challenge with respect to the methods of joining to be used for fabrication. However, the conventional fusion joining has its own difficulty owing to formation of the brittle intermetallic phases. In this present study AA6061-T6 of 2 mm and HIF-GA steel sheet of 1 mm thick are metal inert gas (MIG) brazed with 0.8 mm Al–5Si filler wire under three different heat inputs. The effect of the heat inputs on bead geometry, microstructure and joint properties of MIG brazed Al-steel joints were exclusively studied and characterized by X-ray diffraction, field emission scanning electron microscopy (FESEM), electron probe micro analyzer (EPMA) and high resolution transmission electron microscopy (HRTEM) assisted X-ray spectroscopy (EDS) and selective area diffraction pattern. Finally microstructures were correlated with the performance of the joint. Diffusion induced intermetallic thickness measured by FESEM image and concentration profile agreed well with the numerically calculated one. HRTEM assisted EDS study was used to identify the large size FeAl{sub 3} and small size Fe{sub 2}Al{sub 5} type intermetallic compounds at the interface. The growth of these two phases in A2 (heat input: 182 J mm{sup −1}) is attributed to the slower cooling rate with higher diffusion time (~ 61 s) along the interface in comparison to the same for A1 (heat input: 155 J mm{sup −1}) with faster cooling rate and shorter diffusion time (~ 24 s). The joint efficiency as high as 65% of steel base metal is achieved for A2 which is the optimized parameter in the present study. - Highlights: • AA 6061 and HIF-GA could be successfully joined by MIG brazing. • Intermetallics are exclusively studied and characterized by XRD, FESEM and EPMA. • Intermetallic formation by diffusion is

Valence instabilities in cerium intermetallics

International Nuclear Information System (INIS)

Dijkman, W.H.

1982-01-01

The primary purpose of this investigation was to study the magnetic behaviour of cerium in intermetallic compounds, that show an IV behaviour, e.g. CeSn 3 . In the progress of the investigations, it became of interest to study the effect of changes in the lattice of the IV compound by substituting La or Y for Ce, thus constituting the Cesub(1-x)Lasub(x)Sn 3 and Cesub(1-x)Ysub(x)Sn 3 quasibinary systems. A second purpose was to examine the possibility of introducing instabilities in the valency of a trivalent intermetallic cerium compound: CeIn 3 , also by La and Y-substitutions in the lattice. Measurements on the resulting Cesub(1-x)Lasub(x)In 3 and Cesub(1-x)Ysub(x)In 3 quasibinaries are described. A third purpose was to study the (gradual) transition from a trivalent cerium compound into an IV cerium compound. This was done by examining the magnetic properties of the CeInsub(x)Snsub(3-x) and CePbsub(x)Snsub(3-x) systems. Finally a new possibility was investigated: that of the occurrence of IV behaviour in CeSi 2 , CeSi, and in CeGa 2 . (Auth.)

Synthesis, growth, and studies (crystal chemistry, magnetic chemistry) of actinide-based intermetallic compounds and alloys with a 1.1.1 stoichiometry

International Nuclear Information System (INIS)

Kergadallan, Yann

1993-01-01

The first part of this research thesis reports the study of the synthesis and reactivity of intermetallic compounds with a 1.1.1 stoichiometry. It presents the thermal properties of 1.1.1 compounds: general presentation of physical transitions, and of solid solutions and formation heat, application to actinides (reactivity analysis from phase diagrams, techniques of crystal synthesis and crystal growth. It describes experimental techniques: synthesis, determination of fusion temperature by dilatometry, methods used for crystal growth, characterisation techniques (metallography, X ray diffraction on powders, dilatometry). It discusses the obtained results in terms of characterisation of synthesised samples, of crystal growth, and of measurements of fusion temperature. The second part addresses crystal chemistry studies: structure of compounds with a 1.1.1 stoichiometry (Laves structures, Zr, Ti and Pu compounds), techniques of analysis by X-ray diffraction (on powders and on single crystals), result interpretation (UNiX compounds, AnTAl compounds with T being a metal from group VIII, AnTGa compounds, AnNiGe compounds, distance comparison, structure modifications under pressure). The third part concerns physical issues. The author addresses the following topics: physical properties of intermetallic 1.1.1 compounds (magnetism of yttrium phases, behaviour of uranium-based Laves phases, analysis of pseudo-binary diagrams, physical characteristics of uranium-based 1.1.1 compounds, predictions of physical measurements), analysis techniques (Moessbauer spectroscopy, SQUID for Superconducting Quantum Interference Device), and result interpretation

Sodium borohydride hydrolysis in the presence of intermetallic compound LaNi5

International Nuclear Information System (INIS)

Korobov, I.I.; Mozgina, N.G.

1992-01-01

Kinetics of catalytic hydrolysis of sodium borohydride in the 1 mol/l solution of caustic sodium within the range of 298-318 K in presence of LaNi 5 intermetallic compound is studied. It is established that the reaction has zero order by NaBH 4 and the first one by LaNi 5 . The apparent activation energy of NaBH 4 catalytic hydrolysis in presence of LaNi 5 , calculated on the basis of temperature dependence of reaction velocity, is constant within the temperature range under investigation and constitutes 56$+-$1.5 kJ/mol. Recombination of surface hydrogen on LaNi 5 in molecular one is limiting stage determining NaBH 4 hydrolysis rate

Study on interfacial reaction between lead-free solders and alternative surface finishes

International Nuclear Information System (INIS)

Siti Rabiatul Aisha; Ourdjini, A.; Saliza Osman

2007-01-01

This study investigates the interfacial reactions occurring during reflow soldering between Sn-Ag-Cu lead-free solder and two surface finishes: electroless nickel/ immersion gold (ENIG) and immersion silver (IAg). The study focuses on interfacial reactions evolution and growth kinetics of intermetallic compounds (IMC) formed during soldering and isothermal ageing at 150 degree Celsius for up to 2000 hours. Optical and scanning electron microscopy were used to measure IMC thickness and examine the morphology of IMC respectively, whereas the IMC phases were identified by energy dispersive X-ray analysis (EDX). The results showed that the IMC formed on ENIG finish is thinner compared to that formed on IAg finish. For IAg surface finish, Cu 6 Sn 5 IMCs with scallop morphology are formed at the solder/ surface finish interface after reflow while a second IMC, Cu 3 Sn was formed between the copper and Cu 6 Sn 5 IMC after the isothermal ageing treatment. For ENIG surface finish both (Cu,Ni) 6 Sn 5 and (Ni,Cu) 3 Sn 4 are formed after soldering. Isothermal aging of the solder joints formed on ENIG finish was found to have a significant effect on the morphology of the intermetallics by transforming to more spherical and denser morphology in addition to increase i their thickness with increased ageing time. (author)

NMR measurements in milled GdCo2 and GdFe2 intermetallic compounds

International Nuclear Information System (INIS)

Tribuzy, C.V.B.; Guimaraes, A.P.; Biondo, A.; Larica, C.; Alves, K.M.B.

1998-12-01

We have used the nuclear magnetic resonance technique to study the magnetic and structural properties of the Gd-Co and Gd-Fe metallic systems, starting with the C15 laves phase intermetallic compounds, and submitting them to a high energy milling process. This leads to the amorphization of the samples, as determined by the X-ray diffraction spectra. For the Gd-Co system the NMR study used the 59 Co nucleus; in the Gd-Fe system, 155,157 Gd and 57 Fe were used. Both systems showed segregation of the pure elements, after a few hours of milling. In the Gd-Co system, a single line, of increasing width, was observed in the 59 Co spectrum. In the Gd-Fe system, the 155 Gd and 157 Gd resonances show three lines, arising from electrical quadrupole interaction. With increasing milling time, the lines broaden, and extra lines appear attributed to a cubic phase of Gd; this interpretation is supported by the X-ray analysis of the samples. The 57 Fe NMR spectrum of this system also informs on the direction of magnetization of the samples in the early stages of milling. From 1 h to 7 h of milling, a spectrum of α-Fe was observed. The study of the NMR line intensity as a function of radio frequency (r.f.) power in Gd Co 2 suggests the existence of regions of the samples with different degrees of disorder. We have observed the persistence of NMR signals from the original intermetallic compounds in the samples with up to 10 h and 7 h of milling, respectively, for Gd Co 2 and Gd Fe 2 . (author)

Magneto-caloric effect in the pseudo-binary intermetallic YPrFe{sub 17} compound

Energy Technology Data Exchange (ETDEWEB)

Alvarez, Pablo [Departamento de Fisica, Universidad de Oviedo, Calvo Sotelo, s/n, 33007 Oviedo (Spain); Gorria, Pedro, E-mail: pgorria@uniovi.es [Departamento de Fisica, Universidad de Oviedo, Calvo Sotelo, s/n, 33007 Oviedo (Spain); Sanchez Llamazares, Jose L. [Division de Materiales Avanzados, Instituto Potosino de Investigacion Cientifica y Tecnologica, Camino a la presa San Jose 2055, CP 78216, San Luis Potosi (Mexico); Perez, Maria J. [Departamento de Fisica, Universidad de Oviedo, Calvo Sotelo, s/n, 33007 Oviedo (Spain); Franco, Victorino [Departamento de Fisica de la Materia Condensada, ICMSE-CSIC, Universidad de Sevilla, P.O. Box 1065, 41080 Sevilla (Spain); Reiffers, Marian; Kovac, Jozef [Institute of Experimental Physics, Watsonova 47, SK-04001 Kosice (Slovakia); Puente-Orench, Ines [Institute Laue Langevin, 6 rue Jules Horowitz, 38042 Grenoble (France); Blanco, Jesus A. [Departamento de Fisica, Universidad de Oviedo, Calvo Sotelo, s/n, 33007 Oviedo (Spain)

2011-12-15

Highlights: Black-Right-Pointing-Pointer YPrFe{sub 17} exhibits a broad {Delta}S{sub M}(T) associated with the ferro-to-paramagnetic phase transition (T{sub C} Almost-Equal-To 290 K). Black-Right-Pointing-Pointer We obtain |{Delta}S{sub M}| Almost-Equal-To 2.3 J kg{sup -1} K{sup -1} and RCP Almost-Equal-To 100 J kg{sup -1}for a magnetic field change of 1.5 T. Black-Right-Pointing-Pointer A single master curve for {Delta}S{sub M} is found when compared with other isostructural R{sub 2}Fe{sub 17} binary alloys. - Abstract: We have synthesized the intermetallic YPrFe{sub 17} compound by arc-melting. X-ray and neutron powder diffraction show that the crystal structure is rhombohedral with R3{sup Macron }m space group (Th{sub 2}Zn{sub 17}-type). The investigated compound exhibits a broad isothermal magnetic entropy change {Delta}S{sub M}(T) associated with the ferro-to-paramagnetic phase transition (T{sub C} Almost-Equal-To 290 K). The |{Delta}S{sub M}| ( Almost-Equal-To 2.3 J kg{sup -1} K{sup -1}) and the relative cooling power ( Almost-Equal-To 100 J kg{sup -1}) have been calculated for applied magnetic field changes up to 1.5 T. A single master curve for {Delta}S{sub M} under different values of the magnetic field change can be obtained by a rescaling of the temperature axis. The results are compared and discussed in terms of the magneto-caloric effect in the isostructural R{sub 2}Fe{sub 17} (R = Y, Pr and Nd) binary intermetallic alloys.

The system analysis of temperature and melting enthalpy of intermetallic compounds of antimony-lanthanoids system of Sb Ln, Sb2Ln composition

International Nuclear Information System (INIS)

Badalova, M.A.; Chamanova, M.; Dodkhoev, E.S.; Badalov, A.; Abdusalyamova, M.N.

2015-01-01

Present article is devoted to system analysis of temperature and melting enthalpy of intermetallic compounds of antimony-lanthanoids system of Sb Ln, Sb 2 Ln composition. The melting enthalpy was estimated. The temperature value was determined.

Computer simulations of disordering and amorphization kinetics in intermetallic compounds

International Nuclear Information System (INIS)

Spaczer, M.; Victoria, M.

1995-01-01

Molecular dynamics computer simulations on three intermetallic compounds, Cu 3 Au, Ni 3 Al and NiAl, have been performed to investigate the kinetics of the disordering and amorphization processes. These systems were chosen because reliable embedded atom potentials were developed for the constituent species and their alloys, and also because extended experimental results are available for them. Previous simulations of collision cascades with 5 keV Cu and Ni primary knock-out atom (PKA) showed a significant difference between the evolution of the short range order (SRO) and the crystalline order (CO) parameters in all of the intermetallics: a complete loss of the crystalline structure and only partial chemical disorder in the core of the cascade [T. Diaz de la Rubia et al., Phys. Rev. B 47 (1993) 11483; M. Spaczer et al., Phys. Rev. B 50 (1994) 13204]. The present paper deals with the simulation of the amorphization process in NiAl by 5 and 15 keV Ni PKAs. The kinetic energy of the atoms in the simulated systems was removed on different time scales to mimic strong or weak coupling between electrons and phonons. No evidence of amorphization was found at the end of the cascades created by the 5 keV recoils. However, the 15 keV PKA events showed that (i) in the no-coupling case the system evolved to a highly disordered state, (ii) an amorphous region with about 100 non-lattice atoms was found in the case of weak coupling, (iii) the locally melted and recrystallized region collapsed to a small dislocation loop when medium coupling was used and (iv) a highly ordered state resulted in the case of strong coupling. (orig.)

Effects of surface polishing and annealing on the optical conductivity of intermetallic compounds

CERN Document Server

Rhee, J Y

1999-01-01

The optical conductivity spectra of several intermetallic compounds were measured by spectroscopic ellipsometry. Three spectra were measured for each compound; just after the sample was mechanically polished, at high temperature, and after the sample was annealed at 110 .deg. C for at least one day and cooled to room temperature. An equiatomic FeTi alloy showed the typical effects of annealing after mechanical polishing of surface. The spectrum after annealing had a larger magnitude and sharper structures than the spectrum before annealing. We also observed shifts of peaks in the spectrum. A relatively low-temperature annealing gave rise to unexpectedly substantial effects, and the effects were explained by recrystallization and/or a disorder -> order transition of the surface of the sample which was damaged and, hence, became highly disordered by mechanical polishing. Similar effects were also observed when the sample temperature was lowered. The observed changes upon annealing could partly be explained by p...

The iterative thermal emission method: A more implicit modification of IMC

Energy Technology Data Exchange (ETDEWEB)

Long, A.R., E-mail: arlong.ne@tamu.edu [Department of Nuclear Engineering, Texas A and M University, 3133 TAMU, College Station, TX 77843 (United States); Gentile, N.A. [Lawrence Livermore National Laboratory, L-38, P.O. Box 808, Livermore, CA 94550 (United States); Palmer, T.S. [Nuclear Engineering and Radiation Health Physics, Oregon State University, 100 Radiation Center, Corvallis, OR 97333 (United States)

2014-11-15

For over 40 years, the Implicit Monte Carlo (IMC) method has been used to solve challenging problems in thermal radiative transfer. These problems typically contain regions that are optically thick and diffusive, as a consequence of the high degree of “pseudo-scattering” introduced to model the absorption and reemission of photons from a tightly-coupled, radiating material. IMC has several well-known features that could be improved: a) it can be prohibitively computationally expensive, b) it introduces statistical noise into the material and radiation temperatures, which may be problematic in multiphysics simulations, and c) under certain conditions, solutions can be nonphysical, in that they violate a maximum principle, where IMC-calculated temperatures can be greater than the maximum temperature used to drive the problem. We have developed a variant of IMC called iterative thermal emission IMC, which is designed to have a reduced parameter space in which the maximum principle is violated. ITE IMC is a more implicit version of IMC in that it uses the information obtained from a series of IMC photon histories to improve the estimate for the end of time step material temperature during a time step. A better estimate of the end of time step material temperature allows for a more implicit estimate of other temperature-dependent quantities: opacity, heat capacity, Fleck factor (probability that a photon absorbed during a time step is not reemitted) and the Planckian emission source. We have verified the ITE IMC method against 0-D and 1-D analytic solutions and problems from the literature. These results are compared with traditional IMC. We perform an infinite medium stability analysis of ITE IMC and show that it is slightly more numerically stable than traditional IMC. We find that significantly larger time steps can be used with ITE IMC without violating the maximum principle, especially in problems with non-linear material properties. The ITE IMC method does

The iterative thermal emission method: A more implicit modification of IMC

International Nuclear Information System (INIS)

Long, A.R.; Gentile, N.A.; Palmer, T.S.

2014-01-01

For over 40 years, the Implicit Monte Carlo (IMC) method has been used to solve challenging problems in thermal radiative transfer. These problems typically contain regions that are optically thick and diffusive, as a consequence of the high degree of “pseudo-scattering” introduced to model the absorption and reemission of photons from a tightly-coupled, radiating material. IMC has several well-known features that could be improved: a) it can be prohibitively computationally expensive, b) it introduces statistical noise into the material and radiation temperatures, which may be problematic in multiphysics simulations, and c) under certain conditions, solutions can be nonphysical, in that they violate a maximum principle, where IMC-calculated temperatures can be greater than the maximum temperature used to drive the problem. We have developed a variant of IMC called iterative thermal emission IMC, which is designed to have a reduced parameter space in which the maximum principle is violated. ITE IMC is a more implicit version of IMC in that it uses the information obtained from a series of IMC photon histories to improve the estimate for the end of time step material temperature during a time step. A better estimate of the end of time step material temperature allows for a more implicit estimate of other temperature-dependent quantities: opacity, heat capacity, Fleck factor (probability that a photon absorbed during a time step is not reemitted) and the Planckian emission source. We have verified the ITE IMC method against 0-D and 1-D analytic solutions and problems from the literature. These results are compared with traditional IMC. We perform an infinite medium stability analysis of ITE IMC and show that it is slightly more numerically stable than traditional IMC. We find that significantly larger time steps can be used with ITE IMC without violating the maximum principle, especially in problems with non-linear material properties. The ITE IMC method does

The iterative thermal emission method: A more implicit modification of IMC

Science.gov (United States)

Long, A. R.; Gentile, N. A.; Palmer, T. S.

2014-11-01

For over 40 years, the Implicit Monte Carlo (IMC) method has been used to solve challenging problems in thermal radiative transfer. These problems typically contain regions that are optically thick and diffusive, as a consequence of the high degree of ;pseudo-scattering; introduced to model the absorption and reemission of photons from a tightly-coupled, radiating material. IMC has several well-known features that could be improved: a) it can be prohibitively computationally expensive, b) it introduces statistical noise into the material and radiation temperatures, which may be problematic in multiphysics simulations, and c) under certain conditions, solutions can be nonphysical, in that they violate a maximum principle, where IMC-calculated temperatures can be greater than the maximum temperature used to drive the problem. We have developed a variant of IMC called iterative thermal emission IMC, which is designed to have a reduced parameter space in which the maximum principle is violated. ITE IMC is a more implicit version of IMC in that it uses the information obtained from a series of IMC photon histories to improve the estimate for the end of time step material temperature during a time step. A better estimate of the end of time step material temperature allows for a more implicit estimate of other temperature-dependent quantities: opacity, heat capacity, Fleck factor (probability that a photon absorbed during a time step is not reemitted) and the Planckian emission source. We have verified the ITE IMC method against 0-D and 1-D analytic solutions and problems from the literature. These results are compared with traditional IMC. We perform an infinite medium stability analysis of ITE IMC and show that it is slightly more numerically stable than traditional IMC. We find that significantly larger time steps can be used with ITE IMC without violating the maximum principle, especially in problems with non-linear material properties. The ITE IMC method does however

Abrasive wear of intermetallics

International Nuclear Information System (INIS)

Hawk, J.A.; Alman, D.E.; Wilson, R.D.

1995-01-01

The US Bureau of Mines is investigating the wear behavior of a variety of advanced materials. Among the many materials under evaluation are intermetallic alloys based on the compounds: Fe 3 Al, Ti 3 Al, TiAl, Al 3 Ti, NiAl and MoSi 2 . The high hardness, high modulus, low density, and superior environmental stability of these compounds make them attractive for wear materials. This paper reports on the abrasive wear of alloys and composites based on the above compounds. The abrasive wear behavior of these alloys and composites are compared to other engineering materials used in wear applications

Integrated Marketing Communications (IMC di PT Halo Rumah Bernyanyi

Directory of Open Access Journals (Sweden)

Rebekka Rismayanti

2017-01-01

Full Text Available Abstract: This research aims to describe the effectiveness of Integrated Marketing Communication (IMC in PT Halo Rumah Bernyanyi which, from the perspective of marketing strategy, could be studied by analyzing the segmentation, targeting, and positioning. Using case-study method with in-depth interview, the result shows that the implementation of IMC at PT Halo Rumah Bernyayi is arranged in one single strategy and tend to neglect the complexities of running multi-brand family karaoke-house. This considers as ineffective because it leads to “cannibalization” among brands, especially when costumer’s targetting is overlooked before drafting the IMC plan. Keywords: Business, Integrated Marketing Communication, Marketing   Abstrak: Penelitian ini bertujuan untuk mendeskripsikan efektivitas penerapan Integrated Marketing Communications (IMC yang dilihat dari aspek segmentation, targeting dan positioning. Metode penelitian adalah studi kasus dengan menggunakan wawancara mendalam. Hasil penelitian menunjukkan bahwa penerapan IMC di PT Halo Rumah Bernyanyi dibuat dalam satu strategi dan tidak memerhatikan kompleksitas dari aspek segmentation, targeting dan positioning sebagai pedoman dasar. Langkah tersebut dinilai tidak efektif karena dapat mengakibatkan “kanibalisasi” antar brand, terlebih jika perhatian terhadap target konsumen diabaikan sebelum menyusun perencanaan IMC. Kata Kunci: Bisnis, Integrated Marketing Communications, Pemasaran

ANÁLISE DE AGRUPAMENTO DO IMC E DO IAC E DA RELAÇÃO IAC/IMC EM INDIVÍDUOS COM IDADE ENTRE 6 A 15 ANOS

Directory of Open Access Journals (Sweden)

Julião Soares de Souza Lima Junior

2016-11-01

Full Text Available Conhecer as relações entre dados antropométricos e o estado nutricional das pessoas ajuda no entendimento das tendências em uma população. Este trabalho teve o objetivo de determinar em 62 jovens com idade entre 6 a 15 anos o IMC, o IAC e a relação entre IAC/IMC e utilizar método para agrupamento dos indivíduos. Os dados foram analisados por estatística descritiva e o método de agrupamento Joining. O IMC, o IAC e a Relação IAC/IMC, apresentaram os valores médios de 18,88; 27,62 e 1,51, respectivamente. Os grupos 1 e 2 apresentaram médias maiores que a média geral dos dados para o IMC. Os grupos 2, 3 e 4 apresentaram maiores valores médios que a média geral dos dados para o IAC. Os grupos 3 e 4 com média maior que a media geral para a relação IAC/IMC. Maiores relações de IAC/IMC ocorrem para indivíduos que apresentam menores valores de IMC e os maiores de IAC. O IMC aumenta com a idade e o IAC diminui à medida que a idade aumenta.

Ab initio study of the structural, electronic, elastic and thermal properties of RMn{sub 2}Ge{sub 2} (R = Ca, Nd and Y) intermetallic compounds

Energy Technology Data Exchange (ETDEWEB)

Miloud Abid, O.; Yakoubi, A. [Laboratoire d’Etudes des Matériaux et Instrumentations Expérimentales, Université Djilali Liabes de Sidi Bel-Abbes, 22000 (Algeria); Tadjer, A. [Modeling and Simulation in Materials Science Laboratory, Physics Department, University of Sidi Bel-Abbes, Sidi Bel-Abbes (Algeria); Khenata, R., E-mail: khenata_rabah@yahoo.fr [Laboratoire de Physique Quantique de la Modélisation Mathématique (LPQ3M), Université de Mascara, 29000 (Algeria); Ahmed, R. [Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, UTM Skudai, 81310 Johor (Malaysia); Murtaza, G. [Materials Modeling Laboratory, Department of Physics, Islamia College University, Peshawar (Pakistan); Bin Omran, S. [Department of Physics and Astronomy, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451 (Saudi Arabia); Azam, Sikander [New Technologies – Research Center, University of West Bohemia, Univerzitni 8, 306 14 Pilsen (Czech Republic)

2014-12-15

Highlights: • The calculated structural parameters of RMn{sub 2}Ge{sub 2} (R = Ca, Nd and Y) compounds are found in good agreement with the experimental data. • The structural and band structure calculation reveals that these compounds are ferromagnetic brittle metals. • The elastic and thermodynamic properties for the herein studied compounds are investigated for the first time. - Abstract: Intermetallic RMn{sub 2}Ge{sub 2} ternary compounds have attracted considerable attention from researchers in recent years because they show strong indications for novel magnetic characteristics and they have the potential to reveal the mechanism of superlattices. The study of the paramagnetic, ferromagnetic and antiferromagnetic phases affirms the strong dependence to the distance between atomic species in these compounds. In this study, we investigated the structural, elastic, electronic and thermodynamic properties of the intermetallic RMn{sub 2}Ge{sub 2} (R = Ca, Nd and Y) compounds. To carry out this study, we used the full potential (FP) linearized (L) augmented plane wave plus local orbitals (APW + lo), a scheme of calculations developed within the frame work of density functional theory (DFT). To incorporate the exchange correlation (XC) energy and corresponding potential into the total energy calculations, local density approximation (LDA) parameterized by Perdew and Wang is taken into account. Analysis of the density of states (DOS) profile illustrates the conducting nature of these intermetallic compounds; with a predominantly contribution from the R and Mn-d states. At ambient conditions, calculations for elastic constants (C{sub 11}, C{sub 12}, C{sub 13}, C{sub 44}, C{sub 33} and C{sub 66}) are also performed, which point to their brittle character. In addition, the quasi harmonic Debye model was used to predict the thermal properties, together with relative expansion coefficients and heat capacity.

In vitro evaluation of antimicrobial activity of Lactobacillus rhamnosus IMC 501(®) , Lactobacillus paracasei IMC 502(®) and SYNBIO(®) against pathogens.

Science.gov (United States)

Coman, M M; Verdenelli, M C; Cecchini, C; Silvi, S; Orpianesi, C; Boyko, N; Cresci, A

2014-08-01

Probiotic lactobacilli have a great potential to produce antimicrobial compounds that inhibit and control the microbial pathogen growth. The antimicrobial and antifungal activities of two probiotic strains, Lactobacillus rhamnosus IMC 501(®) and Lactobacillus paracasei IMC 502(®) , and their 1 : 1 combination, named SYNBIO(®) , were studied using four different methods. Using two modified streak methods and a well diffusion method, the inhibitory activity of the probiotics and their metabolites towards six Gram-positive, nine Gram-negative pathogenic bacterial strains and eight Candida strains was tested. Antagonistic effect of probiotic Lactobacillus strains was also investigated by coculturing assay highlighting a significant inhibition of most of the pathogens tested in this study. The combination SYNBIO(®) showed a microbicidal activity against most of the strains tested in the study. Compared with the control, most of the pathogenic bacteria and yeast were inhibited by all probiotic strains tested to various degrees. Screening Lactobacillus strains according to their activity in various environmental conditions could precede the clinical efficacy studies for adjunct treatment with probiotics in cure of different gastrointestinal and vaginal tract infections. © 2014 The Society for Applied Microbiology.

Structural, electronic and elastic properties of RERu{sub 2} (RE=Pr and Nd) Laves phase intermetallic compounds

Energy Technology Data Exchange (ETDEWEB)

Shrivastava, Deepika, E-mail: deepika89shrivastava@gmail.com; Sanyal, Sankar P. [Department of Physics, Barkatullah university, Bhopal, 462026 (India)

2016-05-06

We have performed the first-principles calculations to study the structural, electronic and elastic properties of RERu{sub 2} (RE = Pr and Nd) Laves phase intermetallic compounds using full-potential linearized augmented plane wave (FP-LAPW) method based on density functional theory (DFT) within the generalized gradient approximation (GGA) for exchange and correlation potential. The optimized lattices constant are in reasonable agreement with available experimental data. The electronic properties are analyzed in terms of band structures, total and partial density of states, which confirm their metallic character. The calculated elastic constants infer that these compounds are mechanically stable in C15 (MgCu{sub 2} type) structure and found to be ductile in nature.

The Effectiveness of Al-Si Coatings for Preventing Interfacial Reaction in Al - Mg Dissimilar Metal Welding

OpenAIRE

Wang, Yin; Al-Zubaidy, Basem; Prangnell, Philip

2017-01-01

The dissimilar welding of aluminum to magnesium is challenging because of the rapid formation of brittle intermetallic compounds (IMC) at the weld interface. An Al-Si coating interlayer was selected to address this problem, based on thermodynamic calculations that predicted silicon would change the reaction path to avoid formation of the normally observed binary Al-Mg IMC phases (-Al3Mg2 and -Al12Mg17). Long-term static heat treatments confirmed that a Si-rich coating will preferentially pr...

Oxidation study on as-bonded intermetallic of copper wire–aluminum bond pad metallization for electronic microchip

International Nuclear Information System (INIS)

Joseph Sahaya Anand, T.; Yau, Chua Kok; Huat, Lim Boon

2012-01-01

In this work, influence of Copper free air ball (FAB) oxidation towards Intermetallic Compound (IMC) at Copper wire–Aluminum bond pad metallization (Cu/Al) is studied. Samples are synthesized with different Copper FAB oxidation condition by turning Forming Gas supply ON and OFF. Studies are performed using Optical Microscope (OM), Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM) and line-scan Energy Dispersive X-ray (EDX). SEM result shows there is a cross-sectional position offset from center in sample synthesized with Forming Gas OFF. This is due to difficulty of determining the position of cross-section in manual grinding/polishing process and high occurrence rate of golf-clubbed shape of oxidized Copper ball bond. TEM inspection reveals that the Copper ball bond on sample synthesized with Forming Gas OFF is having intermediate oxidation. Besides, the presence of IMC at the bonding interface of Cu/Al for both samples is seen. TEM study shows voids form at the bonding interface of Forming Gas ON sample belongs to unbonded area; while that in Forming Gas OFF sample is due to volume shrinkage of IMC growth. Line-scan EDX shows the phases present in the interfaces of as-bonded samples are Al 4 Cu 9 (∼3 nm) for sample with Forming Gas ON and mixed CuAl and CuAl 2 (∼15 nm) for sample with Forming Gas OFF. Thicker IMC in sample with Forming Gas OFF is due to cross-section is positioned at high stress area that is close to edge of ball bond. Mechanical ball shear test shows that shear strength of sample with Forming Gas OFF is about 19% lower than that of sample with Forming Gas ON. Interface temperature is estimated at 437 °C for as-bonded sample with Forming Gas ON by using empirical parabolic law of volume diffusion. -- Highlights: ► 3 nm Al 4 Cu 9 are found in sample prepared with Forming Gas ON. ► 15 nm mixed CuAl + CuAl 2 are found in sample prepared with Forming Gas OFF. ► Voids are present at the bonding interfaces of both

Oxidation study on as-bonded intermetallic of copper wire-aluminum bond pad metallization for electronic microchip

Energy Technology Data Exchange (ETDEWEB)

Joseph Sahaya Anand, T., E-mail: anand@utem.edu.my [Faculty of Manufacturing Engineering, University Technical Malaysia Melaka, Hang Tuah Jaya, 76100 Durian Tunggal, Melaka (Malaysia); Yau, Chua Kok [Faculty of Manufacturing Engineering, University Technical Malaysia Melaka, Hang Tuah Jaya, 76100 Durian Tunggal, Melaka (Malaysia); University of Technical Malaysia Supported by Infineon Technology - Malaysia - Sdn. Bhd., Melaka (Malaysia); Huat, Lim Boon [Department of Innovation, Infineon Technology - Malaysia - Sdn. Bhd., FTZ Batu Berendam, 75350 Melaka (Malaysia)

2012-10-15

In this work, influence of Copper free air ball (FAB) oxidation towards Intermetallic Compound (IMC) at Copper wire-Aluminum bond pad metallization (Cu/Al) is studied. Samples are synthesized with different Copper FAB oxidation condition by turning Forming Gas supply ON and OFF. Studies are performed using Optical Microscope (OM), Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM) and line-scan Energy Dispersive X-ray (EDX). SEM result shows there is a cross-sectional position offset from center in sample synthesized with Forming Gas OFF. This is due to difficulty of determining the position of cross-section in manual grinding/polishing process and high occurrence rate of golf-clubbed shape of oxidized Copper ball bond. TEM inspection reveals that the Copper ball bond on sample synthesized with Forming Gas OFF is having intermediate oxidation. Besides, the presence of IMC at the bonding interface of Cu/Al for both samples is seen. TEM study shows voids form at the bonding interface of Forming Gas ON sample belongs to unbonded area; while that in Forming Gas OFF sample is due to volume shrinkage of IMC growth. Line-scan EDX shows the phases present in the interfaces of as-bonded samples are Al{sub 4}Cu{sub 9} ({approx}3 nm) for sample with Forming Gas ON and mixed CuAl and CuAl{sub 2} ({approx}15 nm) for sample with Forming Gas OFF. Thicker IMC in sample with Forming Gas OFF is due to cross-section is positioned at high stress area that is close to edge of ball bond. Mechanical ball shear test shows that shear strength of sample with Forming Gas OFF is about 19% lower than that of sample with Forming Gas ON. Interface temperature is estimated at 437 Degree-Sign C for as-bonded sample with Forming Gas ON by using empirical parabolic law of volume diffusion. -- Highlights: Black-Right-Pointing-Pointer 3 nm Al{sub 4}Cu{sub 9} are found in sample prepared with Forming Gas ON. Black-Right-Pointing-Pointer 15 nm mixed CuAl + CuAl{sub 2} are found

Effects of surface polishing and annealing on the optical conductivity of intermetallic compounds

International Nuclear Information System (INIS)

Rhee, Joo Yull

1999-01-01

The optical conductivity spectra of several intermetallic compounds were measured by spectroscopic ellipsometry. Three spectra were measured for each compound; just after the sample was mechanically polished, at high temperature, and after the sample was annealed at 110 .deg. C for at least one day and cooled to room temperature. An equiatomic FeTi alloy showed the typical effects of annealing after mechanical polishing of surface. The spectrum after annealing had a larger magnitude and sharper structures than the spectrum before annealing. We also observed shifts of peaks in the spectrum. A relatively low-temperature annealing gave rise to unexpectedly substantial effects, and the effects were explained by recrystallization and/or a disorder → order transition of the surface of the sample which was damaged and, hence, became highly disordered by mechanical polishing. Similar effects were also observed when the sample temperature was lowered. The observed changes upon annealing could partly be explained by presumption that the recrystallization would be realized in such a way that the average atomic spacing would be reduced

Thermal expansion and thermal diffusivity properties of Co-Si solid solutions and intermetallic compounds

International Nuclear Information System (INIS)

Ruan, Ying; Li, Liuhui; Gu, Qianqian; Zhou, Kai; Yan, Na; Wei, Bingbo

2016-01-01

Highlights: • Length change difference between rapidly and slowly solidified Co-Si alloy occurs at high temperature. • Generally CTE increases with an increasing Si content. • The thermal diffusion abilities are CoSi 2 > Co 95 Si 5 > Co 90 Si 10 > Co 2 Si > CoSi if T exceeds 565 K. • All the CTE and thermal diffusivity variations with T satisfy linear or polynomial relations. - Abstract: The thermal expansion of Co-Si solid solutions and intermetallic compounds was measured via dilatometric method, compared with the results of first-principles calculations, and their thermal diffusivities were investigated using laser flash method. The length changes of rapidly solidified Co-Si alloys are larger than those of slowly solidified alloys when temperature increases to around 1000 K due to the more competitive atom motion. The coefficient of thermal expansion (α) of Co-Si alloy increases with an increasing Si content, except that the coefficient of thermal expansion of Co 95 Si 5 influenced by both metastable structure and allotropic transformation is lower than that of Co 90 Si 10 at a higher temperature. The thermal expansion abilities of Co-Si intermetallic compounds satisfy the relationship of Co 2 Si > CoSi > CoSi 2 , and the differences of the coefficients of thermal expansion between them increase with the rise of temperature. The thermal diffusivity of CoSi 2 is evidently larger than the values of other Co-Si alloys. If temperature exceeds 565 K, their thermal diffusion abilities are CoSi 2 > Co 95 Si 5 > Co 90 Si 10 > Co 2 Si > CoSi. All the coefficient of thermal expansion and thermal diffusivity variations with temperature satisfy linear or polynomial relations.

Core-level XPS studies of Ce and La intermetallic compounds and their implications for the 4f levels of Ce compounds

International Nuclear Information System (INIS)

Freiburg, C.; Fuggle, J.C.; Hillebrecht, F.U.; Zolnierek, Z.; Laesser, R.

1983-01-01

The 3d core hole X-ray photoelectron spectra (XPS) of approximately 30 intermetallic compounds of La and Ce are reported. Transitions to final states with approximately f 0 , f 1 and f 2 character are observed in some Ce compounds (f 0 and f 1 for La compounds). The results are discussed in terms of the current ideas of the influence of f-counts and f-levels hybridization on core level lineshapes. We cannot find an explanatoin of the observed spectra consisted with the ''promotial model'' where the 4f-count varies and 4f electron was thought to be entirely promoted to the Ce 5d6s valence bands in some compounds. There may be some small charge transfer from the f level, however. In conjunction with ideas on screening processes in XPS the observed lineshapes suggest coupling of the 4f electrons to other states is strongest in those compounds previously thought to have f 0 character. This coupling increases despite a large increase in the Ce-Ce distance when Ce is diluted with Ni or Pd. Thus it cannot be due to direct f-f interaction and must be attributed to coupling with the other valence electrons; possibly those centred on the partner sites. (orig./EZ) [de

Aging treatment characteristics of solder bump joint for high reliability optical module

International Nuclear Information System (INIS)

Kim, Kyung-Seob; Yu, Chung-Hee; Yang, Jun-Mo

2004-01-01

The joint strength and fracture surfaces of Sn-37 mass% Pb and Au stud bumps for photo diode packages after isothermal aging testing were studied experimentally. Al/Au stud bumps and Cu/Sn-37 mass% Pb solders were adopted, and aged for up to 900 h to analyze the effect of intermetallic compound (IMC). The joint strength decreased with aging time. The diffraction patterns of Cu 6 Sn 5 , scallop-shaped IMCs, and planar-shaped Cu 3 Sn were characterized using transmission electron microscopy (TEM). The formation of Kirkendall voids and the growth of IMCs at the solder were found to be a possible mechanism for joint strength reduction

The nuclear quadrupole interaction of {sup 181}Ta in the intermetallic compound Hf{sub 2}Rh

Energy Technology Data Exchange (ETDEWEB)

Ivanovic, N.; Koicki, S.; Cekic, B.; Manasijevic, M.; Koteski, V.; Marjanovic, D. [Institute of Nuclear Sciences VINCA, Laboratory for Nuclear and Plasma Physics, PO Box 522, Belgrade (Yugoslavia)

1999-01-11

The time differential perturbed angular correlation technique has been used to measure the electric field gradient at {sup 181}Ta impurities in the intermetallic compound Hf{sub 2}Rh. The results of the measurements show the presence of two independent quadrupole interactions. At room temperature the interaction frequencies are {omega}{sub Q1} = 58 Mrad s{sup -1} and {omega}{sub Q2} = 239 Mrad s{sup -1}. The electric field gradient V{sub 22}, the corresponding asymmetry parameter {eta} and the distribution parameter {delta} exhibit a pronounced temperature dependence from 78 to 1223 K. (author)

The effect of high-temperature treatment on the formation of nanoscale intermetallic compounds of transition metals in Al-Cu-Mn-Zr alloy

Science.gov (United States)

Monastyrska, Tetiana O.; Berezina, Alla L.; Labur, Tetiana M.; Molebny, Oleh A.; Kotko, Andrii V.

2018-02-01

The precipitation of intermetallic compounds of transition metals during aging of the Al-5.8%Cu-0.3%Mn-0.1%Zr alloy has been studied using DSC, resistometry, X-ray and transmission electron microscopy. In these age hardenable alloys, the nanoscale metastable Θ″ and Θ' phases of the Al2Cu compound are the main strengthening phases, which are formed at low temperature aging of T stresses, etc.) on the aging with the precipitation of strengthening phases has been investigated.

Radiation-induced amorphization of intermetallic compounds: A molecular-dynamics study of CuTi and Cu4Ti3

International Nuclear Information System (INIS)

Lam, N.Q.; Okamoto, P.R.; Sabochick, M.J.

1991-06-01

In the present paper, important results of our recent computer simulation of radiation-induced amorphization in the ordered compounds CuTi and Cu 4 Ti 3 are summarized. The energetic, structural, thermodynamic and mechanical responses of these intermetallics during chemical disordering, point-defect production and heating were simulated, using molecular dynamics and embedded-atom potentials. From the atomistic details obtained, the critical role of radiation-induced structural disorder in driving the crystalline-to-amorphous phase transformation is discussed. 25 refs., 4 figs

Intermetallic compounds of Ni and Ga as catalysts for the synthesis of methanol

DEFF Research Database (Denmark)

Sharafutdinov, Irek; Elkjær, Christian Fink; de Carvalho, Hudson Wallace Pereira

2014-01-01

In this work, we present a detailed study of the formation of supported intermetallic Ni–Ga catalysts for CO2 hydrogenation to methanol. The bimetallic phase is formed during a temperature-programmed reduction of the metal nitrates. By utilizing a combination of characterization techniques......, in particular in situ and ex situ X-ray diffraction, in situ X-ray absorption spectroscopy, transmission electron microscopy combined with electron energy loss spectroscopy and X-ray fluorescence, we have studied the formation of intermetallic Ni–Ga catalysts of two compositions: NiGa and Ni5Ga3. These methods...... demonstrate that the catalysts with the desired intermetallic phase and composition are formed upon reduction in hydrogen and enable us to propose a mechanism of the Ni–Ga nanoparticles formation. By studying the effect of calcination prior to catalyst reduction, we show that the reactivity depends...

Cerium intermetallics with TiNiSi-type structure

Energy Technology Data Exchange (ETDEWEB)

Janka, Oliver; Niehaus, Oliver; Poettgen, Rainer [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie; Chevalier, Bernard [Bordeaux Univ. CNRS (UPR 9048), Pessac (France). Inst. de Chimie de la Matiere Condensee de Bordeaux (ICMCB)

2016-08-01

Intermetallic compounds with the equiatomic composition CeTX that crystallize with the orthorhombic TiNiSi-type structure can be synthesized with electron-rich transition metals (T) and X = Zn, Al, Ga, Si, Ge, Sn, As, Sb, and Bi. The present review focusses on the crystal chemistry and chemical bonding of these CeTX phases and on their physical properties, {sup 119}Sn and {sup 121}Sb Moessbauer spectra, high-pressure effects, hydrogenation reactions and the formation of solid solutions in order to elucidate structure-property relationships. This paper is the final one of a series of four reviews on equiatomic intermetallic cerium compounds [Part I: Z. Naturforsch. 2015, 70b, 289; Part II: Z. Naturforsch. 2015, 70b, 695; Part III: Z. Naturforsch. 2016, 71b, 165].

Thermal, structural, and magnetic studies of metals and intermetallic compounds. Final report

International Nuclear Information System (INIS)

Wallace, W.E.; Craig, R.S.; Rao, V.U.S.

1976-01-01

The powerful magnetism of certain intermetallics, e.g., SmCo 5 , has been established to originate with the powerful magnetic anisotropy of SmCo 5 , not its large magnetization. The anisotropy is, in turn, a crystal field effect. The crystal field interaction has been elucidated by the method of quantum mechanics. Studies of the systems RFe 2 , RFe 3 , RCo 3 , and R 2 Co 7 (R = a rare earth, Y or Th) reveals them to be important for hydrogen storage. In addition, important effects associated with hydrogenation of metals have been found--great enhancement of magnetization of certain systems (e.g., ErFe 2 ) and substantial increase in superconducting transition temperatures (e.g., Zr/sub .5/H/sub .5/V 2 ). Results of studies suggest that the surfaces of rare earth intermetallics are atypical. The spectrum of properties exhibited by the rare earth intermetallics suggests their utility in the efficient capture and storage of solar energy and the use of it for powering a vehicle. These aspects of the systems warrant further attention

Improving of Corrosion Resistance of Aluminum Alloys by Removing Intermetallic Compound

International Nuclear Information System (INIS)

Seri, Osami

2008-01-01

It is well known that iron is one of the most common impurity elements sound in aluminum and its alloys. Iron in the aluminum forms an intermetallic compounds such as FeAl 3 . The FeAl 3 particles on the aluminum surface are one of the most detrimental phases to the corrosion process and anodizing procedure for aluminum and its alloys. Trial and error surface treatment will be carried out to find the preferential and effective removal of FeAl 3 particles on the surfaces without dissolution of aluminum matrix around the particles. One of the preferable surface treatments for the aim of getting FeAl 3 free surface was an electrochemical treatment such as cathodic current density of -2 kAm -2 in a 20-30 mass% HNO 3 solution for the period of 300s. The corrosion characteristics of aluminum surface with FeAl 3 free particles are examined in a 0.1 kmol/m 3 NaCl solution. It is found that aluminum with free FeAl 3 particles shows higher corrosion resistance than aluminum with FeAl 3 particles

Interfacial microstructure and mechanical property of Ti6Al4V/A6061 dissimilar joint by direct laser brazing without filler metal and groove

International Nuclear Information System (INIS)

Song, Zhihua; Nakata, Kazuhiro; Wu, Aiping; Liao, Jinsun

2013-01-01

Laser brazing of Ti6Al4V and A6061-T6 alloys with 2 mm thickness was conducted by focusing laser beam on aluminum alloy side, and the effect of laser offset distance on microstructure and mechanical properties of the dissimilar butt joint was investigated. Laser offset has a great influence on the thickness of interfacial intermetallic compound (IMC) layer and the mechanical property of joint. The thickness of interfacial IMC layer is less than 500 nm, and the average tensile strength of the joint reaches 64% of aluminum base material strength, when suitable welding conditions are used. The interfacial IMC is TiAl 3 . The formation of interfacial IMC layer and its effect on mechanical property of the joint are discussed in the present study.

Thermodynamics and kinetics of the formation of rare earth intermetallics

International Nuclear Information System (INIS)

Deodhar, S.S.

1975-01-01

Heats of reaction of rare earth intermetallics with iron, cobalt and nickel were determined using Differential Thermal Analysis technique. The intermetallic compounds studied were of MgCu 2 type Laves phases and the rare earth elements studied were praseodymium, gadolinium, dyprosium and erbium. The reactions were exothermic and the heats of reaction were generally high. They varied from the low of -2.5 kcal/g mole for Fe 2 Gd to the high of -35.3 kcal/g mole for Ni 2 Er. The magnitudes of heats of reaction were always greater for the intermetallics of heavy rare earth elements. The rare earth intermetallics studied were either ferromagnetic or antiferromagnetic. The variations in the magnetic moments and the heats of reaction with respect to the atomic number of the rare earth elements followed certain trends. The similarities were observed in the trends of two properties. Electronic configuration for the MgCu 2 type rare earth intermetallics is proposed using Engel--Brewer correlation for metallic structures and the structural features of the Laves phase compounds. Kinetics of the reactions between the rare earth elements and iron, cobalt, and nickel was studied. The rate of reaction was diffusion controlled in each case. The Valensi--Carter equation for the diffusion mechanism satisfactorily described the kinetic behavior. The magnitudes of activation energies and frequency factors were determined. The reactions can be characterized by their reaction temperatures since they always begin at definite temperatures. It was observed that the reaction began at a higher temperature if the activation energy for the reaction was high

A Review of Dissimilar Welding Techniques for Magnesium Alloys to Aluminum Alloys

Directory of Open Access Journals (Sweden)

Liming Liu

2014-05-01

Full Text Available Welding of dissimilar magnesium alloys and aluminum alloys is an important issue because of their increasing applications in industries. In this document, the research and progress of a variety of welding techniques for joining dissimilar Mg alloys and Al alloys are reviewed from different perspectives. Welding of dissimilar Mg and Al is challenging due to the formation of brittle intermetallic compound (IMC such as Mg17Al12 and Mg2Al3. In order to increase the joint strength, three main research approaches were used to eliminate or reduce the Mg-Al intermetallic reaction layer. First, solid state welding techniques which have a low welding temperature were used to reduce the IMCs. Second, IMC variety and distribution were controlled to avoid the degradation of the joining strength in fusion welding. Third, techniques which have relatively controllable reaction time and energy were used to eliminate the IMCs. Some important processing parameters and their effects on weld quality are discussed, and the microstructure and metallurgical reaction are described. Mechanical properties of welds such as hardness, tensile, shear and fatigue strength are discussed. The aim of the report is to review the recent progress in the welding of dissimilar Mg and Al to provide a basis for follow-up research.

A Review of Dissimilar Welding Techniques for Magnesium Alloys to Aluminum Alloys

Science.gov (United States)

Liu, Liming; Ren, Daxin; Liu, Fei

2014-01-01

Welding of dissimilar magnesium alloys and aluminum alloys is an important issue because of their increasing applications in industries. In this document, the research and progress of a variety of welding techniques for joining dissimilar Mg alloys and Al alloys are reviewed from different perspectives. Welding of dissimilar Mg and Al is challenging due to the formation of brittle intermetallic compound (IMC) such as Mg17Al12 and Mg2Al3. In order to increase the joint strength, three main research approaches were used to eliminate or reduce the Mg-Al intermetallic reaction layer. First, solid state welding techniques which have a low welding temperature were used to reduce the IMCs. Second, IMC variety and distribution were controlled to avoid the degradation of the joining strength in fusion welding. Third, techniques which have relatively controllable reaction time and energy were used to eliminate the IMCs. Some important processing parameters and their effects on weld quality are discussed, and the microstructure and metallurgical reaction are described. Mechanical properties of welds such as hardness, tensile, shear and fatigue strength are discussed. The aim of the report is to review the recent progress in the welding of dissimilar Mg and Al to provide a basis for follow-up research. PMID:28788646

A Review of Dissimilar Welding Techniques for Magnesium Alloys to Aluminum Alloys.

Science.gov (United States)

Liu, Liming; Ren, Daxin; Liu, Fei

2014-05-08

Welding of dissimilar magnesium alloys and aluminum alloys is an important issue because of their increasing applications in industries. In this document, the research and progress of a variety of welding techniques for joining dissimilar Mg alloys and Al alloys are reviewed from different perspectives. Welding of dissimilar Mg and Al is challenging due to the formation of brittle intermetallic compound (IMC) such as Mg 17 Al 12 and Mg₂Al₃. In order to increase the joint strength, three main research approaches were used to eliminate or reduce the Mg-Al intermetallic reaction layer. First, solid state welding techniques which have a low welding temperature were used to reduce the IMCs. Second, IMC variety and distribution were controlled to avoid the degradation of the joining strength in fusion welding. Third, techniques which have relatively controllable reaction time and energy were used to eliminate the IMCs. Some important processing parameters and their effects on weld quality are discussed, and the microstructure and metallurgical reaction are described. Mechanical properties of welds such as hardness, tensile, shear and fatigue strength are discussed. The aim of the report is to review the recent progress in the welding of dissimilar Mg and Al to provide a basis for follow-up research.

Calorimetric study of the intermetallic compounds UAl2 and PuAl2

International Nuclear Information System (INIS)

Trainor, R.J.; Brodsky, M.B.; Knapp, G.S.

1975-01-01

Results of low temperature specific heat measurements are presented on the strongly paramagnetic intermetallic compounds UAl 2 and PuAl 2 in the temperature intervals 0.9 to 20 0 K, respectively. These compounds are characterized by very narrow 5f bands near the Fermi energy. The low-temperature properties of UAl 2 and PuAl 2 are dominated by long lived spin fluctuations within these narrow bands. In UAl 2 a nearly field-independent T 3 logT contribution dominates the specific heat below 10 0 K, consistent with the predictions of ferromagnetic spin-fluctuation theory. The specific heat, static susceptibility, and electrical resistivity are mutually consistent with T/sub sf/ = 25 +- 10 0 K, where T/sub sf/ is the characteristic spin-fluctuation temperature of the system. Below 20 0 K, the specific heat of PuAl 2 contains a very large linear term, C greater than or approximately equal to 260T (mJ/mole- 0 K), which is approximately four times the magnitude of the measured susceptibility, when both quantities are expressed in the same units. The specific heat of PuAl 2 exhibits no anomalous behavior below 10 0 K, where a resistivity anomaly has been previously obser []ed. The properties of PuAl 2 are qualitatively discussed in terms of antiferromagnetic spin fluctuations. (auth)

Intermetallic semiconducting films

CERN Document Server

Wieder, H H

1970-01-01

Intermetallic Semiconducting Films introduces the physics and technology of AшВv compound films. This material is a type of a polycrystalline semiconductor that is used for galvanomagnetic device applications. Such material has a high electron mobility that is ideal for generators and magnetoresistors. The book discusses the available references on the preparation and identification of the material. An assessment of its device applications and other possible use is also enumerated. The book describes the structures and physical parts of different films. A section of the book covers the three t

Microstructure Characterization and Wear-Resistant Properties Evaluation of an Intermetallic Composite in Ni–Mo–Si System

Directory of Open Access Journals (Sweden)

Boyuan Huang

2017-02-01

Full Text Available Intermetallic compounds have been studied for their potential application as structural wear materials or coatings on engineering steels. In the present work, a newly designed intermetallic composite in a Ni–Mo–Si system was fabricated by arc-melting process with commercially pure metal powders as starting materials. The chemical composition of this intermetallic composite is 45Ni–40Mo–15Si (at %, selected according to the ternary alloy diagram. The microstructure was characterized using optical microscopy (OM, scanning electron microscopy (SEM, X-ray diffraction (XRD, and energy dispersive spectroscopy (EDS, and the wear-resistant properties at room temperature were evaluated under different wear test conditions. Microstructure characterization showed that the composite has a dense and uniform microstructure. XRD results showed that the intermetallic composite is constituted by a binary intermetallic compound NiMo and a ternary Mo2Ni3Si metal silicide phase. Wear test results indicated that the intermetallic composite has an excellent wear-resistance at room-temperature, which is attributed to the high hardness and strong atomic bonding of constituent phases NiMo and Mo2Ni3Si.

[Zn(NH3)4][PtCl6] and [Cd(NH3)4][PtCl6] as precursors for intermetallic compounds PtZn and PtCd

International Nuclear Information System (INIS)

Zadesenets, A.V.; Venediktov, A.B.; Shubin, Yu.V.; Korenev, S.V.

2007-01-01

Double complex salts (tetraamminezinc and tetraamminecadmium hexachloroplatinates) have been synthesized. Their thermal properties have been studied, as well as the products of their degradation in hydrogen and helium atmospheres. Optimal thermolysis schedules have been determined. Thermolysis under hydrogen yields intermetallic compounds PtZn and PtCd [ru

Single crystal growth of europium and ytterbium based intermetallic ...

Indian Academy of Sciences (India)

The difference between an intermetallic compound and a regular metal (e.g., ... intriguing properties, there have not been any reports of thorough investigations of .... scanning electron microscope (SEM) equipped with an energy dispersive ...

Theoretical study of elastic, mechanical and thermodynamic properties of MgRh intermetallic compound

Directory of Open Access Journals (Sweden)

S. Boucetta

2014-03-01

Full Text Available In the last years, Magnesium alloys are known to be of great technological importance and high scientific interest. In this work, density functional theory plane-wave pseudo potential method, with local density approximation (LDA and generalized gradient approximation (GGA are used to perform first-principles quantum mechanics calculations in order to investigate the structural, elastic and mechanical properties of the intermetallic compound MgRh with a CsCl-type structure. Comparison of the calculated equilibrium lattice constant and experimental data shows good agreement. The elastic constants were determined from a linear fit of the calculated stress–strain function according to Hooke's law. From the elastic constants, the bulk modulus B, shear modulus G, Young's modulus E, Poisson's ratio σ, anisotropy factor A and the ratio B/G for MgRh compound are obtained. The sound velocities and Debye temperature are also predicted from elastic constants. Finally, the linear response method has been used to calculate the thermodynamic properties. The temperature dependence of the enthalpy H, free energy F, entropy S, and heat capacity at constant volume Cv of MgRh crystal in a quasi-harmonic approximation have been obtained from phonon density of states and discussed for the first report. This is the first quantitative theoretical prediction of these properties.

Two stages of Kondo effect and competition between RKKY and Kondo in Gd-based intermetallic compound

International Nuclear Information System (INIS)

Vaezzadeh, Mehdi; Yazdani, Ahmad; Vaezzadeh, Majid; Daneshmand, Gissoo; Kanzeghi, Ali

2006-01-01

The magnetic behavior of Gd-based intermetallic compound (Gd 2 Al (1-x) Au x ) in the form of the powder and needle, is investigated. All the samples are an orthorhombic crystal structure. Only the compound with x=0.4 shows the Kondo effect (other compounds have a normal behavior). Although, for the compound in the form of powder, with x=0.4, the susceptibility measurement χ(T) shows two different stages. Moreover for (T>T K2 ) a fall of the value of χ(T) is observable, which indicates a weak presence of ferromagnetic phase. About the two stages of Kondo effect, we observe at the first (T K1 ) an increase of χ(T) and in the second stage (T K2 ) a new remarkable decrease of χ(T) (T K1 >T K2 ). For the sample in the form of needles, the first stage is observable only under high magnetic field. This first stage could be corresponds to a narrow resonance between Kondo cloud and itinerant electron. The second stage, which is remarkably visible for the sample in the form of the powder, can be attribute to a complete polarization of Kondo cloud. Observation of these two Kondo stages could be due to the weak presence of RKKY contribution

Improving of Corrosion Resistance of Aluminum Alloys by Removing Intermetallic Compound

Energy Technology Data Exchange (ETDEWEB)

Seri, Osami [Muroran it., Hokkaido (Japan)

2008-06-15

It is well known that iron is one of the most common impurity elements sound in aluminum and its alloys. Iron in the aluminum forms an intermetallic compounds such as FeAl{sub 3}. The FeAl{sub 3} particles on the aluminum surface are one of the most detrimental phases to the corrosion process and anodizing procedure for aluminum and its alloys. Trial and error surface treatment will be carried out to find the preferential and effective removal of FeAl{sub 3} particles on the surfaces without dissolution of aluminum matrix around the particles. One of the preferable surface treatments for the aim of getting FeAl{sub 3} free surface was an electrochemical treatment such as cathodic current density of -2 kAm{sup -2} in a 20-30 mass% HNO{sub 3} solution for the period of 300s. The corrosion characteristics of aluminum surface with FeAl{sub 3} free particles are examined in a 0.1 kmol/m{sup 3} NaCl solution. It is found that aluminum with free FeAl{sub 3} particles shows higher corrosion resistance than aluminum with FeAl{sub 3} particles.

Low-Temperature Synthesis Routes to Intermetallic Superconductors

Energy Technology Data Exchange (ETDEWEB)

Schaak, Raymond E

2008-01-08

Over the past few years, our group has gained expertise at developing low-temperature solution-based synthetic pathways to complex nanoscale solids, with particular emphasis on nanocrystalline intermetallic compounds. Our synthetic capabilities are providing tools to reproducibly generate intermetallic nanostructures with simultaneous control over crystal structure, composition, and morphology. This DOE-funded project aims to expand these capabilities to intermetallic superconductors. This could represent an important addition to the tools that are available for the synthesis and processing of intermetallic superconductors, which traditionally utilize high-temperature, high-pressure, thin film, or gas-phase vacuum deposition methods. Our current knowledge of intermetallic superconductors suggests that significant enhancements could result from the inherent benefits of low-temperature solution synthesis, e.g. metastable phase formation, control over nanoscale morphology to facilitate size-dependent property studies, robust and inexpensive processability, low-temperature annealing and consolidation, and impurity incorporation (for doping, stoichiometry control, flux pinning, and improving the critical fields). Our focus is on understanding the superconducting properties as a function of synthetic route, crystal structure, crystallite size, and morphology, and developing the synthetic tools necessary to accomplish this. This research program can currently be divided into two classes of superconducting materials: intermetallics (transition metal/post transition metal) and metal carbides/borides. Both involve the development and exploitation of low-temperature synthesis routes followed by detailed characterization of structures and properties, with the goal of understanding how the synthetic pathways influence key superconducting properties of selected target materials. Because of the low-temperature methods used to synthesize them and the nanocrystalline morphologies

FP-LAPW based investigation of structural, electronic and mechanical properties of CePb{sub 3} intermetallic compound

Energy Technology Data Exchange (ETDEWEB)

Pagare, Gitanjali, E-mail: gita-pagare@yahoo.co.in; Jain, Ekta, E-mail: jainekta05@gmail.com [Department of Physics, Government M. L. B. Girls P. G. Autonomous College, Bhopal 462002 (India); Abraham, Jisha Annie, E-mail: disisjisha@yahoo.com [Department of Physics, National Defence Academy, Pune 411023 (India); Sanyal, Sankar P., E-mail: sps.physicsbu@gmail.com [Department of Physics, Barkatullah University, Bhopal 462026 (India)

2015-08-28

A theoretical study of structural, electronic, elastic and mechanical properties of CePb{sub 3} intermetallic compound has been investigated systematically using first principles density functional theory. The calculations are carried out within the three different forms of generalized gradient approximation (GGA) and LSDA for the exchange correlation potential. The ground state properties such as lattice parameter (a{sub 0}), bulk modulus (B) and its pressure derivative (B′) are calculated and obtained lattice parameter of this compound shows well agreement with the experimental results. We have calculated three independent second order elastic constants (C{sub 11}, C{sub 12} and C{sub 44}), which has not been calculated and measured yet. From energy dispersion curves, it is found that the studied compound is metallic in nature. Ductility of this compound is analyzed using Pugh’s criteria and Cauchy's pressure (C{sub 11}-C{sub 12}). The mechanical properties such as Young's modulus, shear modulus, anisotropic ratio, Poison's ratio have been calculated for the first time using the Voigt–Reuss–Hill (VRH) averaging scheme. The average sound velocities (v{sub m}), density (ρ) and Debye temperature (θ{sub D}) of this compound are also estimated from the elastic constants.

Cerium intermetallics CeTX. Review III

Energy Technology Data Exchange (ETDEWEB)

Poettgen, Rainer; Janka, Oliver [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie; Chevalier, Bernard [Bordeaux Univ., Pessac (France). Inst. de Chimie de la Matiere Condensee de Bordeaux

2016-05-01

The structure-property relationships of CeTX intermetallics with structures other than the ZrNiAl and TiNiSi type are systematically reviewed. These CeTX phases form with electron-poor and electron-rich transition metals (T) and X = Mg, Zn, Cd, Hg, Al, Ga, In, Tl, Si, Ge, Sn, Pb, P, As, Sb, and Bi. The review focusses on the crystal chemistry, the chemical bonding peculiarities, and the magnetic and transport properties. Furthermore {sup 119}Sn Moessbauer spectroscopic data, high-pressure studies, hydrogenation reactions and the formation of solid solutions are reviewed. This paper is the third of a series of four reviews on equiatomic intermetallic cerium compound [Part I: R. Poettgen, B. Chevalier, Z. Naturforsch. 2015, 70b, 289; Part II: R. Poettgen, B. Chevalier, Z. Naturforsch. 2015, 70b, 695].

First-principles screening of structural properties of intermetallic compounds on martensitic transformation

Science.gov (United States)

Lee, Joohwi; Ikeda, Yuji; Tanaka, Isao

2017-11-01

Martensitic transformation with good structural compatibility between parent and martensitic phases are required for shape memory alloys (SMAs) in terms of functional stability. In this study, first-principles-based materials screening is systematically performed to investigate the intermetallic compounds with the martensitic phases by focusing on energetic and dynamical stabilities as well as structural compatibility with the parent phase. The B2, D03, and L21 crystal structures are considered as the parent phases, and the 2H and 6M structures are considered as the martensitic phases. In total, 3384 binary and 3243 ternary alloys with stoichiometric composition ratios are investigated. It is found that 187 alloys survive after the screening. Some of the surviving alloys are constituted by the chemical elements already widely used in SMAs, but other various metallic elements are also found in the surviving alloys. The energetic stability of the surviving alloys is further analyzed by comparison with the data in Materials Project Database (MPD) to examine the alloys whose martensitic structures may cause further phase separation or transition to the other structures.

Phase transitions and magnetocaloric effects in intermetallic compounds MnFeX (X=P, As, Si, Ge)

International Nuclear Information System (INIS)

Tegus, O.; Bao Li-Hong; Song Lin

2013-01-01

Since the discovery of giant magnetocaloric effect in MnFeP 1−x As x compounds, much valuable work has been performed to develop and improve Fe 2 P-type transition-metal-based magnetic refrigerants. In this article, the recent progress of our studies on fundamental aspects of theoretical considerations and experimental techniques, effects of atomic substitution on the magnetism and magnetocalorics of Fe 2 P-type intermetallic compounds MnFeX (X=P, As, Ge, Si) is reviewed. Substituting Si (or Ge) for As leads to an As-free new magnetic material MnFeP 1−x Si(Ge) x . These new materials show large magnetocaloric effects resembling MnFe(P, As) near room temperature. Some new physical phenomena, such as huge thermal hysteresis and ‘virgin’ effect, were found in new materials. On the basis of Landau theory, a theoretical model was developed for studying the mechanism of phase transition in these materials. Our studies reveal that MnFe(P, Si) compound is a very promising material for room-temperature magnetic refrigeration and thermo-magnetic power generation. (topical review - magnetism, magnetic materials, and interdisciplinary research)

Moessbauer Study of the Ball Milling Disordering Process of FeAl Intermetallic Compounds

International Nuclear Information System (INIS)

Oleszak, Dariusz; Bruna, Pere; Crespo, Daniel; Pradell, Trinitat

2005-01-01

Structural changes during ball milling of ordered Fe50Al50 intermetallic compounds were studied. X-Ray diffraction allowed the computation of a Long Range Order parameter (LRO) which dropped to zero after a short milling time. The initial B2 ordered structure gradually transforms into a disordered BCC structure, with a final crystallite size of about 25 nm. Moessbauer spectroscopy was used for obtaining a Chemical Short Range Order parameter (CSRO). Using a semiempirical n-body noncentral potential a model of the partially disordered B2 structure was built allowing computing the distribution of Quadrupole Splitting during the disordering process. Comparison between experimental and simulated Moessbauer spectra shows a maximum of disorder in the system for 5h milling, related to the highest value of the lattice spacing and the broader quadrupole hyperfine distribution. However, after milling for times longer than 5h, there is a change on the behavior of the experimental data that cannot be explained by the simple disordering process

Calorimetric investigation into interaction in Zr0.8Ti0.2CrFe-H2 system

International Nuclear Information System (INIS)

Sirotina, R.A.; Verbetskij, V.N.

1993-01-01

For studying Zr 0.8 Ti 0.2 CrFe-H 2 system is applied the calorimetric method with usage of the Tian-Calve type calorimeter. It is shown that up to 488 K in the system there are three characteristic regions: α (hydrogen solution in an intermetallic compounds (IMC)), β (hydrogen solution in a hydride) and α + β (region of coexistence of two phases). Temperature 448 K is near to critical one, when exceeding of which exists only hydrogen solution in a metal matrix. Pressure dependence of hydrogen content in IMC is described satisfactorily by a linear equation

Interaction of intermetallic compounds formed by rare earths, scandium, yttrium and 3d-transition metals, with gaseous ammonia

International Nuclear Information System (INIS)

Shilkin, S.P.; Volkova, L.S.

1992-01-01

Interaction of the RT n intermetallic compounds, where R Sc, Y, rare earths, T = Fe, Co, Ni; n = 2,3,5, with gaseous ammonia under pressure of 1MPa and at temperatures of 293, 723 and 798 K is studied. It is established on the basis of roentgenographic studied, chemical analysis data, X-ray photoelectron spectroscopy and specific surface measurements that metallic matrixes of intermetallides decompose into nitrides and transition metal phases at temperatures of 723 and 798 K under effect of ammonia and independent of structural types of the source materials; partial or complete decomposition of intermetallides through ammonia with formation of transition metal mixture, binary hydrides and nitrides of the most electropositive metal the above systems occurs at the temperature of 293 K depending on the heat of the source compounds and their tendency to decomposition under ammonia effect

High temperature oxidation behavior of TiAl-based intermetallics

International Nuclear Information System (INIS)

Stroosnijder, M.F.; Sunderkoetter, J.D.; Haanappel, V.A.C.

1996-01-01

TiAl-based intermetallic compounds have attracted considerable interest as structural materials for high-temperature applications due to their low density and substantial mechanical strength at high temperatures. However, one major drawback hindering industrial application arises from the insufficient oxidation resistance at temperatures beyond 700 C. In the present contribution some general aspects of high temperature oxidation of TiAl-based intermetallics will be presented. This will be followed by a discussion of the influence of alloying elements, in particular niobium, and of the effect of nitrogen in the oxidizing environment on the high temperature oxidation behavior of such materials

Nanoscale grain growth behaviour of CoAl intermetallic synthesized ...

Indian Academy of Sciences (India)

Grain growth behaviour of the nanocrystalline CoAl intermetallic compound synthesized by mechanical alloying has been studied by isothermal annealing at different temperatures and durations. X-ray diffraction method was employed to investigate structural evolutions during mechanical alloying and annealing processes.

Nanoscale grain growth behaviour of CoAl intermetallic synthesized ...

Indian Academy of Sciences (India)

Administrator

Abstract. Grain growth behaviour of the nanocrystalline CoAl intermetallic compound synthesized by mechanical alloying has been studied by isothermal annealing at different temperatures and durations. X-ray diffraction method was employed to investigate structural evolutions during mechanical alloying and anneal-.

Two stages of Kondo effect and competition between RKKY and Kondo in Gd-based intermetallic compound

Energy Technology Data Exchange (ETDEWEB)

Vaezzadeh, Mehdi [Department of Physics, K.N.Toosi University of Technology, P.O. Box 15875-4416, Tehran (Iran, Islamic Republic of)]. E-mail: mehdi@kntu.ac.ir; Yazdani, Ahmad [Tarbiat Modares University, P.O. Box 14155-4838, Tehran (Iran, Islamic Republic of); Vaezzadeh, Majid [Department of Physics, K.N.Toosi University of Technology, P.O. Box 15875-4416, Tehran (Iran, Islamic Republic of); Daneshmand, Gissoo [Department of Physics, K.N.Toosi University of Technology, P.O. Box 15875-4416, Tehran (Iran, Islamic Republic of); Kanzeghi, Ali [Department of Physics, K.N.Toosi University of Technology, P.O. Box 15875-4416, Tehran (Iran, Islamic Republic of)

2006-05-01

The magnetic behavior of Gd-based intermetallic compound (Gd{sub 2}Al{sub (1-x)}Au{sub x}) in the form of the powder and needle, is investigated. All the samples are an orthorhombic crystal structure. Only the compound with x=0.4 shows the Kondo effect (other compounds have a normal behavior). Although, for the compound in the form of powder, with x=0.4, the susceptibility measurement {chi}(T) shows two different stages. Moreover for (T>T{sub K2}) a fall of the value of {chi}(T) is observable, which indicates a weak presence of ferromagnetic phase. About the two stages of Kondo effect, we observe at the first (T{sub K1}) an increase of {chi}(T) and in the second stage (T{sub K2}) a new remarkable decrease of {chi}(T) (T{sub K1}>T{sub K2}). For the sample in the form of needles, the first stage is observable only under high magnetic field. This first stage could be corresponds to a narrow resonance between Kondo cloud and itinerant electron. The second stage, which is remarkably visible for the sample in the form of the powder, can be attribute to a complete polarization of Kondo cloud. Observation of these two Kondo stages could be due to the weak presence of RKKY contribution.

Integrated Marketing Communications (IMC) di PT Halo Rumah Bernyanyi

OpenAIRE

Rebekka Rismayanti

2017-01-01

Abstract: This research aims to describe the effectiveness of Integrated Marketing Communication (IMC) in PT Halo Rumah Bernyanyi which, from the perspective of marketing strategy, could be studied by analyzing the segmentation, targeting, and positioning. Using case-study method with in-depth interview, the result shows that the implementation of IMC at PT Halo Rumah Bernyayi is arranged in one single strategy and tend to neglect the complexities of running multi-brand family karaoke-house. ...

Intermetallic Compound Growth and Stress Development in Al-Cu Diffusion Couple

Science.gov (United States)

Mishler, M.; Ouvarov-Bancalero, V.; Chae, Seung H.; Nguyen, Luu; Kim, Choong-Un

2018-01-01

This paper reports experimental observations evidencing that the intermetallic compound phase interfaced with Cu in the Al-Cu diffusion couple is most likely α2-Cu3Al phase, not γ-Cu9Al4 phase as previously assumed, and that its growth to a critical thickness may result in interface failure by stress-driven fracture. These conclusions are made based on an interdiffusion study of a diffusion couple made of a thick Cu plate coated with ˜ 2- μm-thick Al thin film. The interface microstructure and lattice parameter were characterized using scanning electron microscopy and x-ray diffraction analysis. Specimens aged at temperature between 623 K (350°C) and 723 K (450°C) for various hours produced consistent results supporting the main conclusions. It is found that disordered α2-Cu3Al phase grows in a similar manner to solid-state epitaxy, probably owing to its structural similarity to the Cu lattice. The increase in the interface strain that accompanies the α2-Cu3Al phase growth ultimately leads to interface fracture proceeding from crack initiation and growth along the interface. This mechanism provides the most consistent explanation for interface failures observed in other studies.

Electron-Poor Polar Intermetallics: Complex Structures, Novel Clusters, and Intriguing Bonding with Pronounced Electron Delocalization.

Science.gov (United States)

Lin, Qisheng; Miller, Gordon J

2018-01-16

Intermetallic compounds represent an extensive pool of candidates for energy related applications stemming from magnetic, electric, optic, caloric, and catalytic properties. The discovery of novel intermetallic compounds can enhance understanding of the chemical principles that govern structural stability and chemical bonding as well as finding new applications. Valence electron-poor polar intermetallics with valence electron concentrations (VECs) between 2.0 and 3.0 e - /atom show a plethora of unprecedented and fascinating structural motifs and bonding features. Therefore, establishing simple structure-bonding-property relationships is especially challenging for this compound class because commonly accepted valence electron counting rules are inappropriate. During our efforts to find quasicrystals and crystalline approximants by valence electron tuning near 2.0 e - /atom, we observed that compositions close to those of quasicrystals are exceptional sources for unprecedented valence electron-poor polar intermetallics, e.g., Ca 4 Au 10 In 3 containing (Au 10 In 3 ) wavy layers, Li 14.7 Mg 36.8 Cu 21.5 Ga 66 adopting a type IV clathrate framework, and Sc 4 Mg x Cu 15-x Ga 7.5 that is incommensurately modulated. In particular, exploratory syntheses of AAu 3 T (A = Ca, Sr, Ba and T = Ge, Sn) phases led to interesting bonding features for Au, such as columns, layers, and lonsdaleite-type tetrahedral frameworks. Overall, the breadth of Au-rich polar intermetallics originates, in part, from significant relativistics effect on the valence electrons of Au, effects which result in greater 6s/5d orbital mixing, a small effective metallic radius, and an enhanced Mulliken electronegativity, all leading to ultimate enhanced binding with nearly all metals including itself. Two other successful strategies to mine electron-poor polar intermetallics include lithiation and "cation-rich" phases. Along these lines, we have studied lithiated Zn-rich compounds in which structural

Chemistry and Properties of Complex Intermetallics from Metallic Fluxes

Energy Technology Data Exchange (ETDEWEB)

Kanatzidis, Mercouri G. [Northwestern Univ., Evanston, IL (United States)

2015-03-28

This project investigated the reaction chemistry and synthesis of new intermetallic materials with complex compositions and structures using metallic fluxes as solvents. It was found that the metallic fluxes offer several key advantages in facilitating the formation and crystal growth of new materials. The fluxes mostly explored were liquid aluminum, gallium and indium. The main purpose of this project was to exploit the potential of metallic fluxes as high temperature solvent for materials discovery in the broad class of intermetallics. This work opened new paths to compound formation. We discovered many new Si (or Ge)-based compounds with novel structures, bonding and physicochemical properties. We created new insights about the reaction chemistry that is responsible for stabilizing the new materials. We also studied the structural and compositional relationships to understand their properties. We investigated the use of Group-13 metals Al, Ga and In as solvents and have generated a wide variety of new results including several new ternary and quaternary materials with fascinating structures and properties as well as new insights as to how these systems are stabilized in the fluxes. The project focused on reactions of metals from the rare earth element family in combination with transition metals with Si and Ge. For example molten gallium has serves both as a reactive and non-reactive solvent in the preparation and crystallization of intermetallics in the system RE/M/Ga/Ge(Si). Molten indium behaves similarly in that it too is an excellent reaction medium, but it gives compounds that are different from those obtained from gallium. Some of the new phase identified in the aluminide class are complex phases and may be present in many advanced Al-matrix alloys. Such phases play a key role in determining (either beneficially or detrimentally) the mechanical properties of advanced Al-matrix alloys. This project enhanced our basic knowledge of the solid state chemistry

Mechanical and oxidation properties of some B2 rare earth–magnesium intermetallic

Energy Technology Data Exchange (ETDEWEB)

Stumphy, Brad [Iowa State Univ., Ames, IA (United States)

2006-12-15

The remainder of Chapter 1 provides background information on three main topics. First is a discussion about the basic structure and composition of binary B2 intermetallic compounds. Second, the mechanical properties of intermetallics are examined, starting with the cause for the typically inherent brittleness observed in B2 intermetallics. A number of B2 compounds have been found to possess an abnormal level of ductility compared to other intermetallics in this class, including a handful of other rare earth–non-rare earth (RM) B2 line compounds, and these findings are also discussed. Finally, oxidation studies of rare earth metals, focusing on yttrium and cerium, as well as magnesium and some B2 materials are discussed. Chapter 2 is an in-depth look into certain aspects of the laboratory work done during this study. The many challenges and difficulties encountered required that a variety of laboratory techniques be attempted in the making, processing, and testing of these two intermetallic materials. The results and ensuing discussion for the mechanical testing that was performed are found in Chapter 3. Tensile and compression testing results for YMg are shown first, followed by those for CeMg. Some samples were made using electrical discharge machining (EDM) while others were polished into the desired shape. A scanning electron microscope (SEM) was utilized to inspect surfaces of the tensile and compression samples. Hardness values and attempts to determine fracture toughness are also recorded before beginning the discussion. Chapter 4 follows the same basic format for the oxidation study portion of the research. Oxidation curves for CeMg are followed by a qualitative chemical analysis using energy dispersive spectroscopy (EDS). The YMg oxidation curves are shown next followed by an x-ray diffraction (XRD) analysis of the oxidation process for this material and a discussion of the results. Chapter 5 is a summary of the research performed in the mechanical and

Integrated Marketing Communications (IMC) Di PT Halo Rumah Bernyanyi

OpenAIRE

Rismayanti, Rebekka

2016-01-01

: This research aims to describe the effectiveness of Integrated Marketing Communication (IMC) in PT Halo Rumah Bernyanyi which, from the perspective of marketing strategy, could be studied by analyzing the segmentation, targeting, and positioning. Using case-study method with in-depth interview, the result shows that the implementation of IMC at PT Halo Rumah Bernyayi is arranged in one single strategy and tend to neglect the complexities of running multi-brand family karaoke-house. This con...

Fracture toughness of ordered intermetallic compounds exhibiting limited ductility and mechanical properties of ion-irradiated polycrystalline NiAl. Final report, July 1, 1986 - June 30, 1997

International Nuclear Information System (INIS)

Ardell, A.J.

1997-09-01

The focus of the research performed under the auspices of this grant changed several times during the lifetime of the project. The initial activity was an investigation of irradiation-induced amorphization of ordered intermetallic compounds, using energetic protons as the bombarding species. Two significant events stimulated a change of direction: (1) the proton accelerating facility that the authors had been using at the California State University at Los Angeles became unavailable late in 1988 because of a personnel matter involving the only individual capable of operating the machine; (2) they learned that disordering and amorphization of intermetallic compounds produced interesting effects on their mechanical properties. Loss of access t the local accelerator prompted a collaboration with Dr. Droa Pedraza of the Oak Ridge National Laboratory (ORNL), enabling access to the accelerator at ORNL. The influence of disordering and amorphization on mechanical properties ultimately stimulated the development of a miniaturized disk-bend testing (MDBT) facility, the intent of which was to provide semiquantitative and even quantitative measures of the mechanical behavior of ion-irradiated ordered intermetallic alloys. The second phase of the project involved the perfection and usage of the MDBT, and involved exploratory experiments on unirradiated materials like amorphous alloy ribbons and brittle grain boundaries in Ni 3 Al. This report is a brief summary of the research highlights of the project, organized according to the activity that was emphasized at the time

Al/Cu Dissimilar Friction Stir Welding with Ni, Ti, and Zn Foil as the Interlayer for Flow Control, Enhancing Mechanical and Metallurgical Properties

Science.gov (United States)

Sahu, Prakash Kumar; Pal, Sukhomay; Pal, Surjya K.

2017-07-01

This research investigates the effects of Ni, Ti, and Zn foil as interlayer, inserted between the faying edges of Al and Cu plates, for controlled intermetallic compound (IMC) formation. The weld tensile strength with Ti and Zn as interlayer is superior to Al base metal strength. This is due to controlled flow of IMCs by diffused Ti interlayer and thin, continuous, and uniform IMC formation in the case of Zn interlayer. Improved flexural stress was observed with interlayer. Weld microhardness varied with different interlayers and purely depends on IMCs present at the indentation point, flow of IMCs, and interlayer hardness. Specimens with interlayer failed at the interface of the nugget and thermomechanical-affected zone (TMAZ) with complete and broken three-dimensional (3-D) grains, indicating transgranular fracture. Phase analysis revealed that Al/Cu IMCs are impeded by Ni and Ti interlayer. The minor binary and ternary IMC phases form adjacent to the interlayer due to diffusion of the material with Al/Cu. Line scan and elemental mapping indicate thin, continuous, and uniform IMCs with enhanced weld metallurgical and mechanical properties for the joints with Zn interlayer. Macrostructural analysis revealed IMC flow variations with and without interlayer. Variation in grain size at different zones is also observed for different interlayers.

Low temperature and surfactant-free synthesis of Pd2Sn intermetallic nanoparticles for ethanol electro-oxidation

International Nuclear Information System (INIS)

Wang, Congmin; Wu, Yurong; Wang, Xin; Zou, Liangliang; Zou, Zhiqing; Yang, Hui

2016-01-01

Many intermetallic compounds have a predictable structure, interesting electronic effects, and useful catalytic properties. In this work, a low temperature, surfactant-free, and one-pot method is used to synthesize carbon supported Pd 2 Sn intermetallic nanoparticles. The superlattice of the product was then characterized using X-ray diffraction and transmission electron microscopy. These synthesized intermetallic nanoparticles were found to exhibit a higher activity and stability for electrocatalysis of the ethanol oxidation reaction in an alkaline media than has been achieved using a traditional Pd/C catalyst, which could be attributed to the structural and compositional stabilities of ordered Pd 2 Sn intermetallic nanoparticles.

Optimization of welding current waveform for dissimilar material with DP590 and Al5052 by Delta-spot welding process

Energy Technology Data Exchange (ETDEWEB)

Kim, Ji Sun; Kim, In Ju; Kim, Young Gon [Korea Institute of Industrial Technology, Gwangju (Korea, Republic of)

2016-06-15

The automotive industry has a target goal to improve fuel consumption due to restricted exhaust gas regulation. For this reason, the applicability of lightweight material, Al alloys, Mg alloys is also being expanded. In this concept, high strength steel, DP590 and light alloy, AL5052 are joined in the right place of the car body. However, it is difficult to join to steel and aluminum by conventional fusion welding. Generally, in respect to dissimilar metal joining by fusion welding, intermetallic compound layer is formed at the joint interface, hot cracking is generated. In this study, the effect of the current waveform on the mechanical characteristics and microstructure in Delta spot welding process of dissimilar metal was investigated. As results, Intermetallic compound (IMC) layer was reduced from 2.355 μm to 1.09 μm by using Delta spot welding process; also the welding current range improved by 50% in the delta spot welding, higher than in the inverter resistance welding. To conclude, the delta spot welding process adopting the process tapes contributes to improving the welding quality for dissimilar metals (Al5052 and DP590) due to a decrease in IMC layer.

Inhibition of the formation of intermetallic compounds in aluminum-steel welded joints by friction stir welding

Directory of Open Access Journals (Sweden)

Torres López, Edwar A.

2015-12-01

Full Text Available Formation of deleterious phases during welding of aluminum and steel is a challenge of the welding processes, for decades. Friction Stir Welding (FSW has been used in an attempt to reduce formation of intermetallic compounds trough reducing the heat input. In this research, dissimilar joint of 6063-T5 aluminum alloy and AISI-SAE 1020 steel were welded using this technique. The temperature of welded joints was measured during the process. The interface of the welded joints was characterized using optical microscopy, scanning and transmission electron microscopy. Additionally, composition measurements were carried out by X-EDS and DRX. The experimental results revealed that the maximum temperature on the joint studied is less than 360 °C. The microstructural characterization in the aluminum-steel interface showed the absence of intermetallic compounds, which is a condition attributed to the use of welding with low thermal input parameters.La unión de juntas aluminio-acero, sin la formación de fases deletéreas del tipo FexAly, ha sido, por décadas, un desafío para los procesos de soldadura. La soldadura por fricción-agitación ha sido empleada para intentar reducir el aporte térmico y evitar la formación de compuestos intermetálicos. Usando esta técnica fueron soldadas juntas disimilares de aluminio 6063-T5 y acero AISI-SAE 1020. La soldadura fue acompañada de medidas de temperatura durante su ejecución. La interfase de las juntas soldadas fue caracterizada utilizando microscopía óptica, electrónica de barrido y electrónica de transmisión. Adicionalmente fueron realizadas medidas puntuales X-EDS y DRX. Los resultados experimentales revelan que la temperatura máxima en la junta es inferior a 360 °C. La caracterización microestructural en la interfase aluminio-acero demostró la ausencia de compuestos intermetálicos, condición atribuida al uso de parámetros de soldadura con bajo aporte térmico.

The Transport Equation in Optically Thick Media: Discussion of IMC and its Diffusion Limit

Energy Technology Data Exchange (ETDEWEB)

Szoke, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Brooks, E. D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2016-07-12

We discuss the limits of validity of the Implicit Monte Carlo (IMC) method for the transport of thermally emitted radiation. The weakened coupling between the radiation and material energy of the IMC method causes defects in handling problems with strong transients. We introduce an approach to asymptotic analysis for the transport equation that emphasizes the fact that the radiation and material temperatures are always different in time-dependent problems, and we use it to show that IMC does not produce the correct diffusion limit. As this is a defect of IMC in the continuous equations, no improvement to its discretization can remedy it.

Effect of Degassing Treatment on the Interfacial Reaction of Molten Aluminum and Solid Steel

Directory of Open Access Journals (Sweden)

Triyono T.

2017-06-01

Full Text Available The gas porosity is one of the most serious problems in the casting of aluminum. There are several degassing methods that have been studied. During smelting of aluminum, the intermetallic compound (IMC may be formed at the interface between molten aluminum and solid steel of crucible furnace lining. In this study, the effect of degassing treatment on the formations of IMC has been investigated. The rectangular substrate specimens were immersed in a molten aluminum bath. The holding times of the substrate immersions were in the range from 300 s to 1500 s. Two degassing treatments, argon degassing and hexachloroethane tablet degassing, were conducted to investigate their effect on the IMC formation. The IMC was examined under scanning electron microscope with EDX attachment. The thickness of the IMC layer increased with increasing immersion time for all treatments. Due to the high content of hydrogen, substrate specimens immersed in molten aluminum without degasser had IMC layer which was thicker than others. Argon degassing treatment was more effective than tablet degassing to reduce the IMC growth. Furthermore, the hard and brittle phase of IMC, FeAl3, was formed dominantly in specimens immersed for 900 s without degasser while in argon and tablet degasser specimens, it was formed partially.

The role of zinc on the chemistry of complex intermetallic compounds

Energy Technology Data Exchange (ETDEWEB)

Xie, Weiwei [Iowa State Univ., Ames, IA (United States)

2014-01-01

Combining experiments and electronic structure theory provides the framework to design and discover new families of complex intermetallic phases and to understand factors that stabilize both new and known phases. Using solid state synthesis and multiple structural determinations, ferromagnetic β-Mn type Co_8+xZn_12–x was analyzed for their crystal and electronic structures.

Magnetic anisotropy in intermetallic compounds containing both uranium and 3d-metal

Czech Academy of Sciences Publication Activity Database

Andreev, Alexander V.; Tereshina, Evgeniya; Gorbunov, Denis; Šantavá, Eva; Šebek, Josef; Žáček, Martin; Homma, Y.; Shiokawa, Y.; Satoh, I.; Yamamura, Y.; Komatsubara, T.; Watanabe, K.; Koyama, K.

2013-01-01

Roč. 114, č. 9 (2013), s. 727-733 ISSN 0031-918X R&D Projects: GA ČR GAP204/12/0150 Institutional support: RVO:68378271 Keywords : uranium intermetallics * magnetic anisotropy * ferromagnetism Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.605, year: 2013

Effects of In and Ni Addition on Microstructure of Sn-58Bi Solder Joint

Science.gov (United States)

Mokhtari, Omid; Nishikawa, Hiroshi

2014-11-01

In this study, the effect of adding 0.5 wt.% and 1 wt.% In and Ni to Sn-58Bi solder on intermetallic compound (IMC) layers at the interface and the microstructure of the solder alloys were investigated during reflow and thermal aging by scanning electron microscopy and electron probe micro-analysis. The results showed that the addition of minor elements was not effective in suppressing the IMC growth during the reflow; however, the addition of 0.5 wt.% In and Ni was effective in suppressing the IMC layer growth during thermal aging. The thickening kinetics of the total IMC layer was analyzed by plotting the mean thickness versus the aging time on log-log coordinates, and the results showed the transition point from grain boundary diffusion control to a volume diffusion control mechanism. The results also showed that the minor addition of In can significantly suppress the coarsening of the Bi phase.

The effect of crystal structure stability on the mobility of gas bubbles in intermetallic uranium compounds

International Nuclear Information System (INIS)

Rest, J.; Hofman, G.L.; Birtcher, R.C.

1988-01-01

Irradiation experiments with certain low-enrichment, high-density, uranium-base intermetallic alloys that are candidate reactor fuel materials, such as U 3 Si and U 6 Fe, have revealed extraordinarily large voids at low and medium fuel burnup. This phenomenon of breakaway swelling does not occur in other fuel types, such as U 3 Si 2 and UAl 3 , where a distribution of relatively small and stable fission gas bubbles forms. In situ transmission electron microscope observations of ion radiation-induced rapid swelling of intermetallic materials are consistent with growth by plastic flow. Large radiation enhancement of plastic flow in amorphous materials has been observed in several independent experiments and is thought to be a general materials phenomenon. The basis for a microscopic theory of fission gas bubble behavior in irradiated amorphous compounds has been formulated. The assumption underlying the overall theory is that the evolution of the porosity from that observed in the crystalline material to that observed in irradiated amorphous U 3 Si as a function of fluence is due to a softening of the irradiated amorphous material. Bubble growth in the low-viscosity material has been approximated by an effective enhanced diffusivity. Mechanisms are included for the radiation-induced softening of the amorphous material, and for a relation between gas atom mobilities and radiation-induced (defect-generated) changes in the material. Results of the analysis indicate that the observed rapid swelling in U 3 Si arises directly from enhanced bubble migration and coalescence due to plastic flow. 34 refs., 11 figs

Structure and mechanical properties of parts obtained by selective laser melting of metal powder based on intermetallic compounds Ni3Al

Science.gov (United States)

Smelov, V. G.; Sotov, A. V.; Agapovichev, A. V.; Nosova, E. A.

2018-03-01

The structure and mechanical properties of samples are obtained from metal powder based on intermetallic compound by selective laser melting. The chemical analysis of the raw material and static tensile test of specimens were made. Change in the samples’ structure and mechanical properties after homogenization during four and twenty-four hours were investigated. A small-sized combustion chamber of a gas turbine engine was performed by the selective laser melting method. The print combustion chamber was subjected to the gas-dynamic test in a certain temperature and time range.

Interfacial Reaction During Dissimilar Joining of Aluminum Alloy to Magnesium and Titanium Alloys

Science.gov (United States)

Robson, J. D.; Panteli, A.; Zhang, C. Q.; Baptiste, D.; Cai, E.; Prangnell, P. B.

Ultrasonic welding (USW), a solid state joining process, has been used to produce welds between AA6111 aluminum alloy and AZ31 magnesium alloys or titanium alloy Ti-6Al-4V. The mechanical properties of the welds have been assessed and it has been shown that it is the nature and thickness of the intermetallic compounds (IMCs) at the joint line that are critical in determining joint strength and particularly fracture energy. Al-Mg welds suffer from a very low fracture energy, even when strength is comparable with that of similar metal Mg-Mg welds, due to a thick IMC layer always being formed. It is demonstrated that in USW of Al-Ti alloy the slow interdiffusion kinetics means that an IMC layer does not form during welding, and fracture energy is greater. A model has been developed to predict IMC formation during welding and provide an understanding of the critical factors that determine the IMC thickness. It is predicted that in Al-Mg welds, most of the lMC thickening occurs whilst the IMC regions grow as separate islands, prior to the formation of a continuous layer.

Study of hyperfine interactions in intermetallic compounds Gd(Ni,Pd,Cu)In, Tb(Ni,Pd)In, Dy(Ni,Pd)In and Ho(Ni,Pd)In

International Nuclear Information System (INIS)

Lapolli, Andre Luis

2006-01-01

Systematic behavior of magnetic hyperfine field (B hf ) in the intermetallic compounds Gd(Ni,Pd,Cu)In Tb(Ni,Pd)In, Dy(Ni,Pd)In and Ho(Ni,Pd)In was studied by Perturbed Gamma-Gamma Angular Correlation spectroscopy. The measurements of B hf were carried out at the rare earth atom and in sites using the nuclear probes 140 Ce and 11 '1Cd respectively. The variation of hyperfine field with temperature, in most cases, follows the Brillouin function predicted from the molecular field theory. The hyperfine field values at rare earth atom sites obtained from 140 Ce probe as well as at in sites obtained from 111 Cd probe for each series of compounds were extrapolated to zero Kelvin B hf (T=0) from these curves. These values were compared with the values of the literature for other compounds containing the same rare earth element and all of them show a linear relationship with the ordering temperature. This indicates that the main contribution to B hf comes from the conduction electron polarization (CEP) through Fermi contact interaction and the principal mechanism of magnetic interaction in these compounds can be described by the RKKY type interaction. The values of B hf (T=0) for each family of intermetallic compounds RNiIn and RPdIn when plotted as a function of 4f spin projection of rare earth element also shows a linear relationship. Exceptions are the results for the compounds RNiIn obtained with 111 Cd probe where a small deviation from linearity is observed. The results of the measurements carried out with the 111 Cd probe were also analyzed to obtain the hyperfine parameters of the quadrupole interaction as a function of temperature for RPdln and GdNiIn compounds. The results show that for the compound GdPdIn there might be some Gd-In disorder at high temperature. (author)

Effect of Interfacial Reaction on the Mechanical Performance of Steel to Aluminum Dissimilar Ultrasonic Spot Welds

Science.gov (United States)

Xu, Lei; Wang, Li; Chen, Ying-Chun; Robson, Joe D.; Prangnell, Philip B.

2016-01-01

The early stages of formation of intermetallic compounds (IMC) have been investigated in dissimilar aluminum to steel welds, manufactured by high power (2.5 kW) ultrasonic spot welding (USW). To better understand the influence of alloy composition, welds were produced between a low-carbon steel (DC04) and two different aluminum alloys (6111 and 7055). The joint strengths were measured in lap shear tests and the formation and growth behavior of IMCs at the weld interface were characterized by electron microscopy, for welding times from 0.2 to 2.4 seconds. With the material combinations studied, the η (Fe2Al5) intermetallic phase was found to form first, very rapidly in the initial stage of welding, with a discontinuous island morphology. Continuous layers of η and then θ (FeAl3) phase were subsequently seen to develop on extending the welding time to greater than 0.7 second. The IMC layer formed in the DC04-AA7055 combination grew thicker than for the DC04-AA6111 welds, despite both weld sets having near identical thermal histories. Zinc was also found to be dissolved in the IMC phases when welding with the AA7055 alloy. After post-weld aging of the aluminum alloy, fracture in the lap shear tests always occurred along the joint interface; however, the DC04-AA6111 welds had higher fracture energy than the DC04-AA7055 combination.

The chemical phenol extraction of intermetallic particles from casting AlSi5Cu1Mg alloy.

Science.gov (United States)

Mrówka-Nowotnik, G; Sieniawski, J; Nowotnik, A

2010-03-01

This paper presents a chemical extraction technique for determination of intermetallic phases formed in the casting AlSi5Cu1Mg aluminium alloy. Commercial aluminium alloys contain a wide range of intermetallic particles that are formed during casting, homogenization and thermomechanical processing. During solidification, particles of intermetallics are dispersed in interdendritic spaces as fine primary phases. Coarse intermetallic compounds that are formed in this aluminium alloy are characterized by unique atomic arrangement (crystallographic structure), morphology, stability, physical and mechanical properties. The volume fraction, chemistry and morphology of the intermetallics significantly affect properties and material behaviour during thermomechanical processing. Therefore, accurate determination of intermetallics is essential to understand and control microstructural evolution in Al alloys. Thus, in this paper it is shown that chemical phenol extraction method can be applied for precise qualitative evaluation. The results of optical light microscopy LOM, scanning electron microscopy SEM and X-ray diffraction XRD analysis reveal that as-cast AlSi5Cu1Mg alloy contains a wide range of intermetallic phases such as Al(4)Fe, gamma- Al(3)FeSi, alpha-Al(8)Fe(2)Si, beta-Al(5)FeSi, Al(12)FeMnSi.

Vacancies and atomic processes in intermetallics - From crystals to quasicrystals and bulk metallic glasses

Energy Technology Data Exchange (ETDEWEB)

Schaefer, Hans-Eckhardt [Institute of Theoretical and Applied Physics, Stuttgart University, Pfaffenwaldring 57, 70569 Stuttgart (Germany); Baier, Falko [Voith Turbo Comp., Alexanderstr. 2, 89552 Heidenheim (Germany); Mueller, Markus A. [GFT Technologies A. G., Filderhauptstr. 142, 70599 Stuttgart (Germany); Reichle, Klaus J. [Philipp-Matthaeus-Hahn School, Jakob-Beutter-Str. 15, 72336 Balingen (Germany); Reimann, Klaus [NXP Semiconductors, Central Research and Development, High Tech Campus 4, 5656 AE Eindhoven (Netherlands); Rempel, Andrey A. [Institute of Solid State Chemistry, Russian Academy of Sciences, Ul. Pervomaiskaya 91, 620041 Ekaterinburg (Russian Federation); Sato, Kiminori [Tokyo Gakugei University, Nukuikita 4-1-1, Koganei, Tokyo 184-8501 (Japan); Ye, Feng [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, 30 Xue Yuan Road, Beijing 100083 (China); Zhang, Xiangyi [Yanshan University, Qinhuangdao 066004 (China); Sprengel, Wolfgang [Institute of Materials Physics, Graz University of Technology, Petersgasse 16, 8010 Graz (Austria)

2011-10-15

A review is given on atomic vacancies in intermetallic compounds. The intermetallic compounds cover crystalline, quasicrystalline, and bulk metallic glass (BMG) structures. Vacancies can be specifically characterized by their positron lifetimes, by the coincident measurement of the Doppler broadening of the two quanta emitted by positron-electron annihilation, or by time-differential dilatometry. By these techniques, high concentrations and low mobilities of thermal vacancies were found in open-structured B2 intermetallics such as FeAl or NiAl, whereas the concentrations of vacancies are low and their mobilities high in close-packed structure as, e.g., L1{sub 2}-Ni{sub 3}Al. The activation volumes of vacancy formation and migration are determined by high-pressure experiments. The favorable sublattice for vacancy formation is found to be the majority sublattice in Fe{sub 61}Al{sub 39} and in MoSi{sub 2}. In the icosahedral quasicrystal Al{sub 70}Pd{sub 21}Mn{sub 9} the thermal vacancy concentration is low, whereas in the BMG Zr{sub 57}Cu{sub 15.4}Ni{sub 12.6}Nb{sub 3}Al{sub 10} thermal vacancies are found in high concentrations with low mobilities. This may determine the basic mechanisms of the glass transition. Making use of the experimentally determined vacancy data, the main features of atomic diffusion studies in crystalline intermetallics, in quasicrystals, and in BMGs can be understood. Manfred Faehnle and his group have substantially contributed to the theoretical understanding of vacancies and diffusion mechanisms in intermetallics. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

The influence of the magnetic state on the thermal expansion in 1:2 rare earth intermetallic compounds

International Nuclear Information System (INIS)

Gratz, E.; Lindbaum, A.

1994-01-01

The attempt is made to demonstrate on some selected rare earth intermetallics the influence of the magnetic state on the thermal expansion. Using the X-ray powder diffraction method we investigated the thermal expansion of some selected nonmagnetic compounds (YAl 2 , YNi 2 and YCo 2 ) and some magnetic RE (rare earth) - cobalt compounds (RCo 2 ) in the temperature range from 4 up to 450 K. All these compounds crystallize in the C15-type structure (cubic Laves phase structure). By comparing the nonmagnetic Y-based compounds we could show that there is an enhanced contribution of the 3d electrons to the thermal expansion in YCo 2 . In the magnetic RCo 2 compounds the induced 3d magnetism gives rise to large volume anomalies at the magnetic ordering temperature T c . Below T c there is in addition a distortion of the cubic unit cell due to the interaction of the magnetically ordered RE ions with the anisotropic crystal field.The thermal expansion of the orthorhombic TmCu 2 , GdCu 2 and YCu 2 compounds has also been investigated for comparison. The influence of the crystal field on the thermal expansion in TmCu 2 in the paramagnetic range (TmCu 2 orders magnetically at T N =6.3 K) has been determined by comparing the thermal expansion of the nonmagnetic YCu 2 with that of TmCu 2 . The data thus obtained are compared with a theoretical model. GdCu 2 , for which the influence of the crystal field can be neglected, has been investigated in order to study the influence of the exchange interaction in the magnetically ordered state (below 42 K). ((orig.))

MD study of primary damage in L10 TiAl structural intermetallics

International Nuclear Information System (INIS)

Voskoboinikov, Roman E.

2013-01-01

Computer modelling by molecular dynamics has been applied to study the radiation damage created in collision cascades in L1 0 TiAl intermetallic compound. Either Al or Ti primary knock-on atoms (PKA) with energy 5 keV ⩽ E PKA ⩽ 20 keV were introduced in the intermetallic crystals at temperatures ranging from 100 K to 900 K. At least 24 different cascade for each (E PKA , T, PKA type) set were modelled in order to simulate a random spatial and temporal distribution of PKAs and provide statistical reliability of the results. The total yield of more than 760 simulated cascades is the largest yet reported for this binary intermetallic material. A comprehensive treatment of the modelling results has been carried out. The number of Frenkel pairs, fraction of Al and Ti vacancies, self-interstitial atoms and anti-sites as a function of (E PKA , T, PKA type) has been established. Preferred formation of Al self-interstitial atoms has been detected in L1 0 TiAl structural intermetallics exposed to irradiation

Inhibition of the formation of intermetallic compounds in aluminum-steel welded joints by friction stir welding; Inhibicion de la formacion de compuestos intermetalicos en juntas aluminio-acero soldadas por friccion-agitacion

Energy Technology Data Exchange (ETDEWEB)

Torres Lopez, E. A.; Ramirez, A. J.

2015-07-01

Formation of deleterious phases during welding of aluminum and steel is a challenge of the welding processes, for decades. Friction Stir Welding (FSW) has been used in an attempt to reduce formation of intermetallic compounds trough reducing the heat input. In this research, dissimilar joint of 6063-T5 aluminum alloy and AISI-SAE 1020 steel were welded using this technique. The temperature of welded joints was measured during the process. The interface of the welded joints was characterized using optical microscopy, scanning and transmission electron microscopy. Additionally, composition measurements were carried out by X-EDS and DRX. The experimental results revealed that the maximum temperature on the joint studied is less than 360 degree centigrade. The microstructural characterization in the aluminum-steel interface showed the absence of intermetallic compounds, which is a condition attributed to the use of welding with low thermal input parameters. (Author)

The effect of graphene on the intermetallic and joint strength of Sn-3.5Ag lead-free solder

Science.gov (United States)

Mayappan, R.; Salleh, A.; Andas, J.

2017-09-01

Solder has been widely used in electronic industry as interconnection for electronic packaging. European Union and Japan have restricted the use of Sn-Pb solder as it contains lead which can harmful to human health and environment. Due to this, many researches have been done in order to find a suitable replacement for the lead solder. Although many lead-free solders are available, the Sn-3.5Ag solder with the addition of graphene seem to be a suitable candidate. In this study, a 0.07 wt% graphene nanosheet was added into the Sn-3.5Ag solder and this composite solder was prepared under powder metallurgy method. The solder was reacted with copper substrate at 250 °C for one minute. For joint strength analysis, two copper strips were soldered together. The solder joint was aged at temperature 100 °C for 500 hours. Scanning Electron Microscope (SEM) was used to observe the interfacial reaction and Instron machine was used to determine the joint strength. Cu6Sn5 intermetallic layer was formed at the interface between the Cu substrate and the solders. Composite solder showed the retardation of the intermetallic growth compared to the plain solder. The thickness value of the intermetallic was used to calculate the growth rate the IMC. The graphene nanosheets added solder has lower growth rate which is 3.86 × 10-15 cm2/s compared to the plain solder 7.15 × 10-15 cm2/s. Shear strength analysis show that the composite solder has higher joint compared to the plain solder.

First principle study on generalized-stacking-fault energy surfaces of B2-AlRE intermetallic compounds

Science.gov (United States)

Li, Shaorong; Wang, Shaofeng; Wang, Rui

2011-12-01

First-principles calculations are used to predict the generalized-stacking-fault energy (GSFE) surfaces of AlRE intermetallics. The calculations employ the projector augmented-wave (PAW) method within the generalized gradient approximation (GGA) using the density functional theory (DFT). GSFE curves along {1 1 0} direction, {1 1 0} direction and {1 1 0} direction have been calculated. The fitted GSFE surfaces have been obtained from the Fourier series based on the translational symmetry. In order to illuminate the reasonable of our computational accuracy, we have compared our theoretical results of B2 intermetallics YCu with the previous calculated results. The unstable-stacking-fault energy (γus) on the {1 1 0} plane has the laws of AlPr, and directions. For the antiphase boundary (APB) energy, that of AlSc is the lowest in the calculated AlRE intermetallics. So the superdislocation with the Burgers vector along direction of AlSc will easily split into two superpartials.

Crystal structure and magnetic state of pseudo-binary intermetallic compounds Ho(Cosub(1-x)Nisub(x))sub(5)

International Nuclear Information System (INIS)

Chuev, V.V.; Kelarev, V.V.; Pirogov, A.N.; Sidorov, S.K.; Koryakova, V.S.

1983-01-01

In the range of 1.8-1000 K intermetallic compounds Ho(Cosub(1-x)Nisub(x))sub(5) have been investigated neutronographically and roentgenographically. Crystal structure of two series of samples: HoCosub(5.5-5.5x)Nisub(5x) and HoCosub(5-5x)Nisub(5x) is studied. It is shown that Ni atoms mainly occupy positions 2c, Co atoms - positions 3g; coordinates of atoms and position occupation of TbCu 7 type structure are specified. Analysis of magnetic structure is made, angles of magnetic momenta orientation as to crystallographic axes are determined. Magnetic phase diagram is built. Concentrational dependences of sublattice magnetization: Msub(Ho)(x), Mdsub(2c)(x), Mdsub(3g)(x) are determined

Complex magnetic behaviour and evidence of a superspin glass state in the binary intermetallic compound Er5Pd2

Science.gov (United States)

Sharma, Mohit K.; Yadav, Kavita; Mukherjee, K.

2018-05-01

The binary intermetallic compound Er5Pd2 has been investigated using dc and ac magnetic susceptibilities, magnetic memory effect, isothermal magnetization, non-linear dc susceptibility, heat capacity and magnetocaloric effect studies. Interestingly, even though the compound does not show geometrical frustration it undergoes glassy magnetic phase transition below 17.2 K. Investigation of dc magnetization and heat capacity data divulged absence of long-ranged magnetic ordering. Through the magnetic memory effect, time dependent magnetization and ac susceptibility studies it was revealed that the compound undergoes glass-like freezing below 17.2 K. Analysis of frequency dependence of this transition temperature through scaling and Arrhenius law; along with the Mydosh parameter indicate, that the dynamics in Er5Pd2 are due to the presence of strongly interacting superspins rather than individual spins. This phase transition was further investigated by non-linear dc susceptibility and was characterized by static critical exponents γ and δ. Our results indicate that this compound shows the signature of superspin glass at low temperature. Additionally, both conventional and inverse magnetocaloric effect was observed with a large value of magnetic entropy change and relative cooling power. Our results suggest that Er5Pd2 can be classified as a superspin glass system with large magnetocaloric effect.

Studies of hydrogen absorption and desorption processes in advanced intermetallic hydrides

Energy Technology Data Exchange (ETDEWEB)

Sato, Masashi

2005-07-01

This work is a part of the research program performed in the Department of Energy Systems, Institute for Energy Technology (Kjeller, Norway), which is focused on the development of the advanced hydrogen storage materials. The activities are aimed on studies of the mechanisms of hydrogen interactions with intermetallic alloys with focus on establishing an interrelation between the crystal structure, thermodynamics and kinetics of the processes in the metal-hydrogen systems, on the one hand, and hydrogen storage properties (capacity, rates of desorption, hysteresis). Many of the materials under investigation have potential to be applied in applications, whereas some already have been commercialised in the world market. A number of metals take up considerable amounts of hydrogen and form chemical compounds with H, metal hydrides. Unfortunately, binary hydrides are either very stable (e.g. for the rare earth metals [RE], Zr, Ti, Mg: metal R) or are formed at very high applied pressures of hydrogen gas (e.g. for the transition metals, Ni, Co, Fe, etc.: Metal T). However, hydrogenation process becomes easily reversible at very convenient from practical point of view conditions, around room temperature and at H2 pressures below 1 MPa for the two-component intermetallic alloys R{sub x}T{sub y}. This raised and maintains further interest to the intermetallic hydrides as solid H storage materials. Materials science research of this thesis is focused on studies of the reasons staying behind the beneficial effect of two non-transition elements M(i.e., In and Sn) contributing to the formation of the ternary intermetallic alloys R{sub x}T{sub y}M{sub 2}., on the hydrogen storage behaviours. Particular focus is on two aspects where the remarkable improvement of ordinary metal hydrides is achieved via introduction of In and Sn: a) Increase of the volume density of stored hydrogen in solid materials to the record high level. b) Improvement of the kinetics of hydrogen charge and

Magnetism in rare-earth metals and rare-earth intermetallic compounds

International Nuclear Information System (INIS)

Johansson, B.; Nordstroem, L.; Eriksson, O.; Brooks, M.S.S.

1991-01-01

Some of out recent local spin density electronic structure calculations for a number of ferromagnetic rare-earth systems are reviewed. A simplified model of the level densities for rare-earth (R) transition metal (M) intermetallic compounds, R m M n , is used to describe in a simple way the main features of their basic electronic structure. Explicit calculations for LuFe 2 and RFe 2 (R=Gd-Yb) systems are presented, where a method to treat simultaneously the localized 4f and the conduction electron spin magnetism is introduced. Thereby it becomes possible to calculate the K RM exchange coupling constant. This method is also used to study theoretically the permanent magnet material Nd 2 Fe 14 B. The electronic structure of the anomalous ferromagnets CeFe 2 and CeCo 5 is discussed and an induced 4f itinerant magnetism is predicted. The γ-α transition in cerium metal is considered, and results from calculations including orbital polarization are presented, where a volume collapse of 10% is obtained. On one side of the transition the 4f electrons are calculated to be essentially non-bonding (localized) and on the other side they are found to contribute to the metallic bonding and this difference in behaviour gives rise to the volume collapse. Recent calculations by Wills, Eriksson and Boring for the crystal structure changes in cerium metal under high pressure are discussed. Their successful results imply an itinerant picture for the 4f electrons in α-cerium. Consequently this strongly supports the view that the γ-α phase transformation is caused by a Mott transition of the 4f electrons. (orig.)

Recent advances in ordered intermetallics

International Nuclear Information System (INIS)

Liu, C.T.

1995-01-01

Ordered intermetallic alloys based on aluminides and silicides offer many advantages for structural use at elevated temperatures in hostile environments. Their attractive properties include excellent oxidation and corrosion resistance, light weight, and superior strength at elevated temperatures. The major concern for structural use of intermetallics was their low ductility and poor fracture resistance at ambient temperatures. For the past ten years, considerable effort has been devoted to the research and development of ordered intermetallic alloys, and good progress has been made on understanding intrinsic and extrinsic factors controlling brittle fracture in intermetallic alloys based on aluminides and silicides. Parallel efforts on alloy design have led to the development of a number of ductile and strong intermetallic alloys based on Ni(3)Al, NiAl, Fe(3)Al, FeAl, Ti(3)Al and TiAl systems for structural applications. (orig.)

First principles electronic and thermal properties of some AlRE intermetallics

Science.gov (United States)

Srivastava, Vipul; Sanyal, Sankar P.; Rajagopalan, M.

2008-10-01

A study on structural and electronic properties of non-magnetic cubic B 2-type AlRE (RE=Sc, Y, La, Ce, Pr and Lu) intermetallics has been done theoretically. The self-consistent tight binding linear muffin tin orbital method is used to describe the electronic properties of these intermetallics at ambient and at high pressure. These compounds show metallic behavior under ambient conditions. The variation of density of states under compression indicates some possibility of structural phase transformation in AlLa, AlCe and AlPr. Thermal properties like Debye temperature and Grüneisen constant are calculated at T=0 K and at ambient pressure within the Debye-Grüneisen model and compared with the others’ theoretical results. Our results are in good agreement. We have also performed a pressure-induced variation of Debye temperature and have found a decrease in Debye temperature around 40 kbar in AlRE (RE=La, Ce, Pr) intermetallics.

First principles electronic and thermal properties of some AlRE intermetallics

Energy Technology Data Exchange (ETDEWEB)

Srivastava, Vipul [Department of Physics, Barkatullah University, Hoshangabad Road, Bhopal, Madhya Pradesh 462 026 (India)], E-mail: vips73@yahoo.com; Sanyal, Sankar P. [Department of Physics, Barkatullah University, Hoshangabad Road, Bhopal, Madhya Pradesh 462 026 (India); Rajagopalan, M. [Department of Physics, Anna University, Chennai-600 025 (India)

2008-10-01

A study on structural and electronic properties of non-magnetic cubic B{sub 2}-type AlRE (RE=Sc, Y, La, Ce, Pr and Lu) intermetallics has been done theoretically. The self-consistent tight binding linear muffin tin orbital method is used to describe the electronic properties of these intermetallics at ambient and at high pressure. These compounds show metallic behavior under ambient conditions. The variation of density of states under compression indicates some possibility of structural phase transformation in AlLa, AlCe and AlPr. Thermal properties like Debye temperature and Grueneisen constant are calculated at T=0 K and at ambient pressure within the Debye-Grueneisen model and compared with the others' theoretical results. Our results are in good agreement. We have also performed a pressure-induced variation of Debye temperature and have found a decrease in Debye temperature around 40 kbar in AlRE (RE=La, Ce, Pr) intermetallics.

First principles electronic and thermal properties of some AlRE intermetallics

International Nuclear Information System (INIS)

Srivastava, Vipul; Sanyal, Sankar P.; Rajagopalan, M.

2008-01-01

A study on structural and electronic properties of non-magnetic cubic B 2 -type AlRE (RE=Sc, Y, La, Ce, Pr and Lu) intermetallics has been done theoretically. The self-consistent tight binding linear muffin tin orbital method is used to describe the electronic properties of these intermetallics at ambient and at high pressure. These compounds show metallic behavior under ambient conditions. The variation of density of states under compression indicates some possibility of structural phase transformation in AlLa, AlCe and AlPr. Thermal properties like Debye temperature and Grueneisen constant are calculated at T=0 K and at ambient pressure within the Debye-Grueneisen model and compared with the others' theoretical results. Our results are in good agreement. We have also performed a pressure-induced variation of Debye temperature and have found a decrease in Debye temperature around 40 kbar in AlRE (RE=La, Ce, Pr) intermetallics

Strong, ductile, and thermally stable Cu-based metal-intermetallic nanostructured composites.

Science.gov (United States)

Dusoe, Keith J; Vijayan, Sriram; Bissell, Thomas R; Chen, Jie; Morley, Jack E; Valencia, Leopolodo; Dongare, Avinash M; Aindow, Mark; Lee, Seok-Woo

2017-01-09

Bulk metallic glasses (BMGs) and nanocrystalline metals (NMs) have been extensively investigated due to their superior strengths and elastic limits. Despite these excellent mechanical properties, low ductility at room temperature and poor microstructural stability at elevated temperatures often limit their practical applications. Thus, there is a need for a metallic material system that can overcome these performance limits of BMGs and NMs. Here, we present novel Cu-based metal-intermetallic nanostructured composites (MINCs), which exhibit high ultimate compressive strengths (over 2 GPa), high compressive failure strain (over 20%), and superior microstructural stability even at temperatures above the glass transition temperature of Cu-based BMGs. Rapid solidification produces a unique ultra-fine microstructure that contains a large volume fraction of Cu 5 Zr superlattice intermetallic compound; this contributes to the high strength and superior thermal stability. Mechanical and microstructural characterizations reveal that substantial accumulation of phase boundary sliding at metal/intermetallic interfaces accounts for the extensive ductility observed.

Effects of Ag addition on solid–state interfacial reactions between Sn–Ag–Cu solder and Cu substrate

International Nuclear Information System (INIS)

Yang, Ming; Ko, Yong-Ho; Bang, Junghwan; Kim, Taek-Soo; Lee, Chang-Woo; Li, Mingyu

2017-01-01

Low–Ag–content Sn–Ag–Cu (SAC) solders have attracted much recent attention in electronic packaging for their low cost. To reasonably reduce the Ag content in Pb–free solders, a deep understanding of the basic influence of Ag on the SAC solder/Cu substrate interfacial reaction is essential. Previous studies have discussed the influence of Ag on the interfacial intermetallic compound (IMC) thickness. However, because IMC growth is the joint result of multiple factors, such characterizations do not reveal the actual role of Ag. In this study, changes in interfacial IMCs after Ag introduction were systemically and quantitatively characterized in terms of coarsening behaviors, orientation evolution, and growth kinetics. The results show that Ag in the solder alloy affects the coarsening behavior, accelerates the orientation concentration, and inhibits the growth of interfacial IMCs during solid–state aging. The inhibition mechanism was quantitatively discussed considering the individual diffusion behaviors of Cu and Sn atoms, revealing that Ag inhibits interfacial IMC growth primarily by slowing the diffusion of Cu atoms through the interface. - Highlights: •Role of Ag in IMC formation during Sn–Ag–Cu soldering was investigated. •Ag affects coarsening, crystallographic orientation, and IMC growth. •Diffusion pathways of Sn and Cu are affected differently by Ag. •Ag slows Cu diffusion to inhibit IMC growth at solder/substrate interface.

Effects of Ag addition on solid–state interfacial reactions between Sn–Ag–Cu solder and Cu substrate

Energy Technology Data Exchange (ETDEWEB)

Yang, Ming [Micro-Joining Center, Korea Institute of Industrial Technology (KITECH), Incheon 21999 (Korea, Republic of); Ko, Yong-Ho [Micro-Joining Center, Korea Institute of Industrial Technology (KITECH), Incheon 21999 (Korea, Republic of); Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291, Daehak-ro, Yuseong-gu, Daejeon 34141 (Korea, Republic of); Bang, Junghwan [Micro-Joining Center, Korea Institute of Industrial Technology (KITECH), Incheon 21999 (Korea, Republic of); Kim, Taek-Soo [Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291, Daehak-ro, Yuseong-gu, Daejeon 34141 (Korea, Republic of); Lee, Chang-Woo, E-mail: cwlee@kitech.re.kr [Micro-Joining Center, Korea Institute of Industrial Technology (KITECH), Incheon 21999 (Korea, Republic of); Li, Mingyu, E-mail: myli@hit.edu.cn [Shenzhen Key Laboratory of Advanced Materials, Harbin Institute of Technology Shenzhen Graduate School, Shenzhen 518055 (China)

2017-02-15

Low–Ag–content Sn–Ag–Cu (SAC) solders have attracted much recent attention in electronic packaging for their low cost. To reasonably reduce the Ag content in Pb–free solders, a deep understanding of the basic influence of Ag on the SAC solder/Cu substrate interfacial reaction is essential. Previous studies have discussed the influence of Ag on the interfacial intermetallic compound (IMC) thickness. However, because IMC growth is the joint result of multiple factors, such characterizations do not reveal the actual role of Ag. In this study, changes in interfacial IMCs after Ag introduction were systemically and quantitatively characterized in terms of coarsening behaviors, orientation evolution, and growth kinetics. The results show that Ag in the solder alloy affects the coarsening behavior, accelerates the orientation concentration, and inhibits the growth of interfacial IMCs during solid–state aging. The inhibition mechanism was quantitatively discussed considering the individual diffusion behaviors of Cu and Sn atoms, revealing that Ag inhibits interfacial IMC growth primarily by slowing the diffusion of Cu atoms through the interface. - Highlights: •Role of Ag in IMC formation during Sn–Ag–Cu soldering was investigated. •Ag affects coarsening, crystallographic orientation, and IMC growth. •Diffusion pathways of Sn and Cu are affected differently by Ag. •Ag slows Cu diffusion to inhibit IMC growth at solder/substrate interface.

Microstructural Evolution and Mechanical Behavior of High Temperature Solders: Effects of High Temperature Aging

Science.gov (United States)

Hasnine, M.; Tolla, B.; Vahora, N.

2018-04-01

This paper explores the effects of aging on the mechanical behavior, microstructure evolution and IMC formation on different surface finishes of two high temperature solders, Sn-5 wt.% Ag and Sn-5 wt.% Sb. High temperature aging showed significant degradation of Sn-5 wt.% Ag solder hardness (34%) while aging has little effect on Sn-5 wt.% Sb solder. Sn-5 wt.% Ag experienced rapid grain growth as well as the coarsening of particles during aging. Sn-5 wt.% Sb showed a stable microstructure due to solid solution strengthening and the stable nature of SnSb precipitates. The increase of intermetallic compound (IMC) thickness during aging follows a parabolic relationship with time. Regression analysis (time exponent, n) indicated that IMC growth kinetics is controlled by a diffusion mechanism. The results have important implications in the selection of high temperature solders used in high temperature applications.

PENERAPAN INTEGRATED MARKETING COMMUNICATION (IMC DI MEDIA RADIO SEGARA FM BANGKALAN

Directory of Open Access Journals (Sweden)

Ipin Rahmadi

2016-03-01

Full Text Available This study intends to reveal the facts of the application of the concept of IMCwas done by radio Segara Bangkalan.Study used the concept theory of IMCwas applied of direct marketing, sales promotion, public relations, personalselling, advertising, and media interaction, marketing which relativelyapplied to the public audience of Segara radio.This of study used a qualitative descriptive method which intends to findout the phenomenon of concerns about the research subject. In holistic anddescriptive manner in the form of words and language, the data collectionmethods in this used study documentation, techniques, observation anddirectly interviews to the field.The application of IMC was good to increase the number of radio audience inSegara, from the six concepts of IMC, advertising, public relations, personalselling, sales promotion, direct marketing, and interactive ware marketing,applied directly by radio to the public, so that produce good results againstthe Segara radio.Keywords: IMC (Integrated Marketing Communication, Media Radio,Audience

PERAN IMC DALAM PEMILIHAN MOMMILK MANAHAN SOLO SEBAGAI PILIHAN KUNJUNGAN KONSUMEN

Directory of Open Access Journals (Sweden)

Endang Sri Purwaningsih

2017-03-01

Full Text Available This study is to explore the IMC activity conducted by Mommilk Manahan Solo in attracting consumen interest. The research was conducted in Mommilk restaurant, Surakarta city. The quantitative descriptive methodology arranged to support the study while the measurement scale used Likert scale. The sample of this study was Mommilk costumers. The questioners were distributed to gauge the IMC activity, which can be devided into three specific factors; promotion and direct sell, public relation, and advertisement. In the outline of factors are the variables that influence the customers in selecting Mommilk as a preference. The result shows that the IMC activity is positively influence costumers to choose Mommilk as a preference. This study finds that several actions taken by the restaurant management successfully influenced the customers to choose Mommilk instead of others restaurants. Those actions become refence for the management to develop the service in order to attract the costumers.

Statistical thermodynamics -- A tool for understanding point defects in intermetallic compounds

International Nuclear Information System (INIS)

Ipser, H.; Krachler, R.

1996-01-01

The principles of the derivation of statistical-thermodynamic models to interpret the compositional variation of thermodynamic properties in non-stoichiometric intermetallic compounds are discussed. Two types of models are distinguished: the Bragg-Williams type, where the total energy of the crystal is taken as the sum of the interaction energies of all nearest-neighbor pairs of atoms, and the Wagner-Schottky type, where the internal energy, the volume, and the vibrational entropy of the crystal are assumed to be linear functions of the numbers of atoms or vacancies on the different sublattices. A Wagner-Schottky type model is used for the description of two examples with different crystal structures: for β'-FeAl (with B2-structure) defect concentrations and their variation with composition are derived from the results of measurements of the aluminum vapor pressure, the resulting values are compared with results of other independent experimental methods; for Rh 3 Te 4 (with an NiAs-derivative structure) the defect mechanism responsible for non-stoichiometry is worked out by application of a theoretical model to the results of tellurium vapor pressure measurements. In addition it is shown that the shape of the activity curve indicates a certain sequence of superstructures. In principle, there are no limitations to the application of statistical thermodynamics to experimental thermodynamic data as long as these are available with sufficient accuracy, and as long as it is ensured that the distribution of the point defects is truly random, i.e. that there are no aggregates of defects

Electromigration-induced back stress in critical solder length for three-dimensional integrated circuits

Energy Technology Data Exchange (ETDEWEB)

Huang, Y. T.; Hsu, H. H.; Wu, Albert T., E-mail: atwu@ncu.edu.tw [Department of Chemical and Materials Engineering, National Central University, Jhongli City 320, Taiwan (China)

2014-01-21

Because of the miniaturization of electronic devices, the reliability of electromigration has become a major concern when shrinking the solder dimensions in flip-chip joints. Fast reaction between solders and electrodes causes intermetallic compounds (IMCs) to form, which grow rapidly and occupy entire joints when solder volumes decrease. In this study, U-grooves were fabricated on Si chips as test vehicles. An electrode-solder-electrode sandwich structure was fabricated by using lithography and electroplating. Gaps exhibiting well-defined dimensions were filled with Sn3.5Ag solders. The gaps between the copper electrodes in the test sample were limited to less than 15 μm to simulate microbumps. The samples were stressed at various current densities at 100 °C, 125 °C, and 150 °C. The morphological changes of the IMCs were observed, and the dimensions of the IMCs were measured to determine the kinetic growth of IMCs. Therefore, this study focused on the influence of back stress caused by microstructural evolution in microbumps.

Syntheses and properties of several metastable and stable hydrides derived from intermetallic compounds under high hydrogen pressure

Energy Technology Data Exchange (ETDEWEB)

Filipek, S.M., E-mail: sfilipek@unipress.waw.pl [Institute of High Pressure Physics PAS, ul. Sokolowska 29, 01-142 Warsaw (Poland); Paul-Boncour, V. [ICMPE-CMTR, CNRS-UPEC, 2-8 rue Henri Dunant, 94320 Thiais (France); Liu, R.S. [Department of Chemistry, National Taiwan University, Taipei 106, Taiwan (China); Jacob, I. [Unit Nuclear Eng., Ben Gurion University of the Negev, Beer-Sheva (Israel); Tsutaoka, T. [Dept. of Sci. Educ., Grad. School of Educ., Hiroshima University, Hiroshima (Japan); Budziak, A. [Institute of Nuclear Physics PAS, 31-342 Kraków (Poland); Morawski, A. [Institute of High Pressure Physics PAS, ul. Sokolowska 29, 01-142 Warsaw (Poland); Sugiura, H. [Yokohama City University, 22-2 Seto, Kanazawa-ku, Yokohama 236-0027 (Japan); Zachariasz, P. [Institute of Electron Technology Cracow Division, ul. Zablocie 39, 30-701 Krakow (Poland); Dybko, K. [Institute of Physics, PAS, 02-668 Warsaw (Poland); Diduszko, R. [Tele and Radio Research Institute, ul. Ratuszowa 11, Warsaw (Poland)

2016-12-01

Brief summary of our former work on high hydrogen pressure syntheses of novel hydrides and studies of their properties is supplemented with new results. Syntheses and properties of a number of hydrides (unstable, metastable or stable in ambient conditions) derived under high hydrogen pressure from intermetallic compounds, like MeT{sub 2}, MeNi{sub 5}, Me{sub 7}T{sub 3}, Y{sub 6}Mn{sub 23} and YMn{sub 12} (where Me = zirconium, yttrium or rare earth; T = transition metal) are presented. Stabilization of ZrFe{sub 2}H{sub 4} due to surface phenomena was revealed. Unusual role of manganese in hydride forming processes is pointed out. Hydrogen induced phase transitions, suppression of magnetism, antiferromagnetic-ferromagnetic and metal-insulator or semimetal-metal transitions are described. Equations of state (EOS) of hydrides submitted to hydrostatic pressures up to 30 GPa are presented and discussed.

An Analysis of Source Tilting and Sub-cell Opacity Sampling for IMC

Energy Technology Data Exchange (ETDEWEB)

Wollaeger, Ryan T. [Los Alamos National Laboratory; Urbatsch, Todd J. [Los Alamos National Laboratory; Wollaber, Allan B. [Los Alamos National Laboratory; Densmore, Jeffery D. [Los Alamos National Laboratory

2012-08-02

Implicit Monte Carlo (IMC) is a stochastic method for solving the radiative transfer equations for multiphysics application with the material in local thermodynamic equilibrium. The IMC method employs a fictitious scattering term that is computed from an implicit discretization of the material temperature equation. Unfortunately, the original histogram representation of the temperature and opacity with respect to the spatial domain leads to nonphysically fast propagation of radiation waves through optically thick material. In the past, heuristic source tilting schemes have been used to mitigate the numerical teleportation error of the radiation particles in IMC that cause this overly rapid radiation wave propagation. While improving the material temperature profile throughout the time duration, these tilting schemes alone do not generally alleviate the teleportation error to suitable levels. Another means of potentially reducing teleportation error in IMC is implementing continuous sub-cell opacities based on sub-cell temperature profiles. We present here an analysis of source tilting and continuous sub-cell opacity sampling applied to various discretizations of the temperature equation. Through this analysis, we demonstrate that applying both heuristics does not necessarily yield more accurate results if the discretization of the material equation is inconsistent with the Monte Carlo sub-cell transport.

Influence of low Co substitution on magnetoelastic properties of HoFe11Ti intermetallic compound

International Nuclear Information System (INIS)

Motevalizadeh, L.; Tajabor, N.; Sanavi Khoshnoud, D.; Fruchart, D.; Pourarian, F.

2012-01-01

The thermal expansion and magnetostriction of HoFe 11−x Co x Ti (x=0, 0.3, 0.7 and 1) intermetallic compounds were measured, using the strain gauge method in the temperature range 77–590 K under applied magnetic fields up to 1.5 T. Results show that for samples with x=0 and 0.3, both linear thermal expansion and linear thermal expansion coefficient exhibit anomalies below the Curie temperature. Below room temperature, the spontaneous volume magnetostriction decreases with Co content. For all compounds studied, the anisotropic magnetostriction shows similar behaviour in the measured temperature range. The magnetostriction compensation occurs above room temperature in all samples. The volume magnetostriction shows a linear dependence on the applied field and by approaching the Curie temperature this trend changes to parastrictive behaviour. The results of the spontaneous magnetostriction are discussed based on the local magnetic moment model. The contribution of magnetostriction attributed to the magnetic sublattices R and T (Fe or Co) is discussed. - Highlights: ► Magnetostriction of HoFe 11−x Co x Ti have been measured by using strain gauge method. ► The measurement was carried in 77–590 K under applied magnetic fields up to 1.5 T. ► Spontaneous volume magnetostriction and Invar effect decrease with Co substitution. ► Ho sublattice has negative contribution to spontaneous volume magnetostriction. ► Absolute values of anisotropic magnetostriction decrease slightly with Co content.

The influence of pressure on diffusion leading to intermetallic compounds

International Nuclear Information System (INIS)

Adda, Y.; Beyeler, M.; Kirianenko, A.; Pernot, B.

1961-01-01

Some investigators A.D. LE CLAIRE, J.L. ZAMBROW, L. CASTLEMAN, have shown that the application of uniaxial pressure parallel to the direction of diffusion may notably modify the kinetics of growth of the intermediate phases which can be formed in this direction. The interpretation of this phenomenon being obscure, an attempt is made to explain it by detailed analysis of the experimental facts. The microscopic studies of the kinetics of growth of the zones formed shows particularly in the couples Uranium-Copper and Uranium-Nickel that it is influenced in a similar manner by a uniaxial pressure and a hydrostatic one. On the other hand the rate of growth of these zones increases as a function of the applied pressure in the systems Uranium-Copper, Uranium-Nickel and Uranium-Aluminium (this effect being particularly marked in Uranium-Aluminium). To determine with precision the limits of the range of stability of the intermetallic compounds, the curves of concentration penetration characteristics of the diffusion have been established by means of the CASTAING electronic microanalyser. The examination of the results indicates that when diffusion takes place without external pressure (couples U-Cu and U-Ni) or with a pressure less than 300 kg/cm 2 (couple U-Al) the concentration varies notably in the compounds obtained, which theoretically are stoichiometric. Thus, when crossing the zone of diffusion of one base metal to another one notes a continual passage of: UCu 4.70 to UCu 5.25 in the couple U-Cu; UNi 4.75 to UNi 5.25 in the couple U-Ni; UAl 2.2 to UAl 3.3 in the couple U-Al. If an uniaxial or hydrostatic pressure above 500 kg/cm 2 is applied to the couples U-Cu and U-Ni, or above 1000 kg/cm 2 for the couple U-Al, the composition is then constant in the zones formed. It corresponds to: UCu 5 in the couple U-Cu; UNi 5 in the couple U-Ni; UAl 3 in the couple U-Al. These results are confirmed by an X-ray diffraction study, mainly in the U-Cu system. Experiments in

Intermetallic-Based High-Temperature Materials

Energy Technology Data Exchange (ETDEWEB)

Sikka, V.K.

1999-04-25

The intermetallic-based alloys for high-temperature applications are introduced. General characteristics of intermetallics are followed by identification of nickel and iron aluminides as the most practical alloys for commercial applications. An overview of the alloy compositions, melting processes, and mechanical properties for nickel and iron aluminizes are presented. The current applications and commercial producers of nickel and iron aluminizes are given. A brief description of the future prospects of intermetallic-based alloys is also given.

X-ray diffraction study of the phase purity, order and texture of ductile B2 intermetallics

Energy Technology Data Exchange (ETDEWEB)

Mulay, R.P.; Wollmershauser, J.A.; Heisel, M.A. [Materials Science and Engineering, University of Virginia, Charlottesville, VA 22904-4745 (United States); Bei, H. [Oak Ridge National Laboratory, Material Science and Technology Division, Oak Ridge, TN 37831 (United States); Russell, A.M. [Iowa State University, Department of Materials Science and Engineering, Ames, IA 50011 (United States); Agnew, S.R., E-mail: sra4p@virginia.edu [Materials Science and Engineering, University of Virginia, Charlottesville, VA 22904-4745 (United States)

2010-04-15

Representatives (AgY, CuY, AgEr, CuDy, MgY and MgCe) of the newly discovered family of ductile stoichiometric B2 intermetallic (metal-rare-earth element, MR) compounds were characterized by X-ray diffraction, to determine if their anomalous ductility is related to an exceptional level of phase purity, lack of chemical ordering or a strong crystallographic texture. Brittle NiAl served as an anti-type in this study. We found that all of the rare-earth compounds, except MgY, have a significant volume fraction ({approx}5-20 vol.%) of second phases (M{sub 2}R intermetallics and R{sub 2}O{sub 3} oxides), which has not been reported in previous studies of these materials. The most ductile of observed MR compounds, AgY, is highly ordered. A moderate texture was observed in AgY, which may explain its higher ductility (using polycrystal modeling) as compared to other MR compounds. However, the intrinsic polycrystalline ductility of these compounds in the randomly textured state (like that observed in CuY) still has no specific, definitive explanation.

X-ray diffraction study of the phase purity, order and texture of ductile B2 intermetallics

International Nuclear Information System (INIS)

Mulay, R.P.; Wollmershauser, J.A.; Heisel, M.A.; Bei, H.; Russell, A.M.; Agnew, S.R.

2010-01-01

Representatives (AgY, CuY, AgEr, CuDy, MgY and MgCe) of the newly discovered family of ductile stoichiometric B2 intermetallic (metal-rare-earth element, MR) compounds were characterized by X-ray diffraction, to determine if their anomalous ductility is related to an exceptional level of phase purity, lack of chemical ordering or a strong crystallographic texture. Brittle NiAl served as an anti-type in this study. We found that all of the rare-earth compounds, except MgY, have a significant volume fraction (∼5-20 vol.%) of second phases (M 2 R intermetallics and R 2 O 3 oxides), which has not been reported in previous studies of these materials. The most ductile of observed MR compounds, AgY, is highly ordered. A moderate texture was observed in AgY, which may explain its higher ductility (using polycrystal modeling) as compared to other MR compounds. However, the intrinsic polycrystalline ductility of these compounds in the randomly textured state (like that observed in CuY) still has no specific, definitive explanation.

The Effects of Grain Refinement and Rare Earth Intermetallics on Mechanical Properties of As-Cast and Wrought Magnesium Alloys

Science.gov (United States)

Pourbahari, Bita; Mirzadeh, Hamed; Emamy, Massoud

2018-03-01

The effects of rare earth intermetallics and grain refinement by alloying and hot extrusion on the mechanical properties of Mg-Gd-Al-Zn alloys have been studied to elucidate some useful ways to enhance the mechanical properties of magnesium alloys. It was revealed that aluminum as an alloying element is a much better grain refining agent compared with gadolinium, but the simultaneous presence of Al and Gd can refine the as-cast grain size more efficiently. The presence of fine and widely dispersed rare earth intermetallics was found to be favorable to achieve finer recrystallized grains during hot deformation by extrusion. The presence of coarse dendritic structure in the GZ61 alloy, grain boundary eutectic containing Mg17Al12 phase in the AZ61 alloy, and rare earth intermetallics with unfavorable morphology in the Mg-4Gd-2Al-1Zn alloy was found to be detrimental to mechanical properties of the alloy in the as-cast condition. As a result, the microstructural refinement induced by hot extrusion process resulted in a significant enhancement in strength and ductility of the alloys. The presence of intermetallic compounds in the extruded Mg-4Gd-2Al-1Zn and Mg-2Gd-4Al-1Zn alloys deteriorated tensile properties, which was related to the fact that such intermetallic compounds act as stress risers and microvoid initiation sites.

The possibility of the mixed valence state in the uranium intermetallic compounds: UCoGa5, U2Ru2Sn and U2RuGa8

International Nuclear Information System (INIS)

Troc, Robert

2007-01-01

The mixed valence (MV) phenomenon has been observed so far in a large number of various compounds but containing only lanthanides. These properties are usually associated with the mixing of the localised f-state and the band states. The usual valence state for magnetic uranium intermetallics is the trivalent state 5f 3 or hybridised 5f 2 6d 1 , both are nearly degenerate in energy and can compete for a stability of the compound. In some cases a gain in an energy minimum may be achieved by very fast fluctuating between these two states with a time of 10 -14 s, which does not allow to yield the ordered state even if the exchange interactions (favourite the U-U distances) would be able for that. The latter cases seem to concern the described here intermetallics: one ternary compound based on Co, UCoGa 5 , and the two uranium ternary compounds based on Ru, namely U 2 Ru 2 Sn and U 2 RuGa 8 which all crystallize in a tetragonal unit cell. All these compounds show a maximum in their temperature dependences of the magnetic susceptibility measured along and perpendicular to the c-axis. Such a behaviour, which is reminiscent of a number of Ce (Sm, Eu) and Yb compounds for which χ(T) has in the past been considered by Sales and Wohlleben (SW) by applying their ICF model or by Lawrance et al. following their scaling procedure. It turned out that these phenomenological models can also be applied to the considered here two Ru-based uranium ternaries from which some reliable energy parameters could be found. In order to further support the mixing valence scenario for the first such cases in uranium compounds presented here, the transport and thermodynamic properties are also discussed. However, some of the most important results confirming the MV state, e.g., in U 2 RuGa 8 , has recently been achieved from the inelastic neutron scattering performed in the Rutherford Appleton Laboratory on the ISIS facility. From these measurements a characteristic gap of 60 meV has been

Dissolution rates and solubility of some metals in liquid gallium and aluminum

International Nuclear Information System (INIS)

Yatsenko, S P; Sabirzyanov, N A; Yatsenko, A S

2008-01-01

The effect of liquid gallium and aluminum on some hard metals leading to dissolution and formation of intermetallic compounds (IMC) under static conditions and rotation of a specimen is studied. The solubility parameters from the Clapeyron-Clausius equation were considered to estimate the stability of still not studied metals. The presented experimental data on solubility and corrosion in a wide temperature range allow to calculate a number of parameters useful in manufacturing and application of master-alloys

FY 1997 report on the improvement of toughness of silicide system intermetallic compounds by complex texture; 1997 nendo chosa hokokusho (fukugo soshikika ni yoru silicide kei kinzokukan kagobutsu no kyojinsei kaizen)

Energy Technology Data Exchange (ETDEWEB)

NONE

1998-03-01

In order to develop new materials superior in both room- temperature ductility and high-temperature strength, the basic data on MoSi2 intermetallic compounds with complex texture were stored. Intermetallic compound is one of the promising candidates of new super heat-resistant materials superior to conventional super heat-resistant alloys, however, it is extremely poor in ductility at room temperature. Based on available information on isothermal sectional phase diagrams of ternary system (Mo-Si-X system) composed of Mo silicide and the third element (X), some alloy systems were selected in consideration of use of carbide and nitride stably existing as dispersed phase of deposits at high temperature. A knowledge on phase diagrams of ternary system specimens with various compositions was obtained through arc melting, X-ray diffraction and texture observation, and heat treatment conditions for obtaining target complex textures were also determined. Storage of the basic data suggested that improvement of the ductility is possible by forming fine texture through addition of the third element and teat treatment. 21 refs., 58 figs., 15 tabs.

Combined effects of ultrasonic vibration and manganese on Fe-containing inter-metallic compounds and mechanical properties of Al-17Si alloy with 3wt.%Fe

Directory of Open Access Journals (Sweden)

Lin Chong

2013-05-01

Full Text Available The research studied the combined effects of ultrasonic vibration (USV and manganese on the Fe-containing inter-metallic compounds and mechanical properties of Al-17Si-3Fe-2Cu-1Ni (wt.% alloys. The results showed that, without USV, the alloys with 0.4wt.% Mn or 0.8wt.% Mn both contain a large amount of coarse plate-like δ-Al4(Fe,MnSi2 phase and long needle-like β-Al5(Fe,MnSi phase. When the Mn content changes from 0.4wt.% to 0.8wt.% in the alloys, the amount and the length of needle-like β-Al5(Fe,MnSi phase decrease and the plate-like δ-Al4(Fe,MnSi2 phase becomes much coarser. After USV treatment, the Fe-containing compounds in the alloys are refined and exist mainly as δ-Al4(Fe,MnSi2 particles with an average grain size of about 20 μm, and only a small amount of β-Al5(Fe,MnSi phase remains. With USV treatment, the ultimate tensile strengths (UTS of the alloys containing 0.4wt.%Mn and 0.8wt.%Mn at room temperature are 253 MPa and 262 MPa, respectively, and the ultimate tensile strengths at 350 °C are 129 MPa and 135 MPa, respectively. It is considered that the modified morphology and uniform distribution of the Fe-containing inter-metallic compounds, which are caused by the USV process, are the main reasons for the increase in the tensile strength of these two alloys.

Abnormal accumulation of intermetallic compound at cathode in a SnAg3.0Cu0.5 lap joint during electromigration

International Nuclear Information System (INIS)

Li Mingyu; Chang Hong; Pang Xiaochao; Wang Ling; Fu Yonggao

2011-01-01

Interfacial reactions in a SnAg 3.0 Cu 0.5 /Cu lap joint for naked and encompassed specimens were investigated contrastively under electric current stressing. After applying a constant direct current at 6.5 A for 144 h, an abnormal accumulation of bulk Cu 6 Sn 5 intermetallic compound was found at the cathode for the naked specimen. But normal polarization phenomenon arose for the encompassed specimen at the same current density for 504 h. The abnormal accumulation phenomenon was explained by the mechanism that thermomigration and stress migration induced by temperature gradient dominated the migration process. A three-dimensional joint simulation model was designed to demonstrate how current crowding and temperature gradient can enhance the local atomic flux.

Mechanical properties of intermetallics formed during thermal aging of Cu-Al ball bonds

NARCIS (Netherlands)

Kouters, M.H.M.; Gubbels, G.H.M.; O'Halloran, O.; Rongen, R.; Weltevreden, E.R.

2011-01-01

In high power automotive electronics copper wire bonding is regarded as most promising alternative for gold wire bonding in 1st level interconnects and therefore subjected to severe functional requirements. In the Cu-Al ball bond interface the growth of intermetallic compounds may deteriorate the

Characteristics of indomethacin-saccharin (IMC-SAC) co-crystals prepared by an anti-solvent crystallization process.

Science.gov (United States)

Chun, Nan-Hee; Wang, In-Chun; Lee, Min-Jeong; Jung, Yun-Taek; Lee, Sangkil; Kim, Woo-Sik; Choi, Guang J

2013-11-01

The creation of co-crystals of various insoluble drug substances has been extensively investigated as a promising approach to improve their pharmaceutical performance. In this study, co-crystal powders of indomethacin and saccharin (IMC-SAC) were prepared by an anti-solvent (water) addition and compared with co-crystals by evaporation method. No successful synthesis of a pharmaceutical co-crystal powder via an anti-solvent approach has been reported. Among solvents examined, methanol was practically the only one that resulted in the formation of highly pure IMC-SAC co-crystal powders by anti-solvent approach. The mechanism of a preferential formation of IMC-SAC co-crystal to IMC was explained with two aspects: phase solubility diagram and solution complexation concept. Accordingly, the anti-solvent approach can be considered as a competitive route for producing pharmaceutical co-crystal powders with acceptable properties. Copyright © 2013 Elsevier B.V. All rights reserved.

A feedforward IMC structure for controlling the charging temperature of a TES system of a solar cooker

International Nuclear Information System (INIS)

Mawire, A.; McPherson, M.

2008-01-01

A feedforward internal model control (IMC) structure for controlling and maintaining the outlet charging temperature of a thermal energy storage (TES) system of a solar cooker is presented. The TES system consists of a packed pebble bed in thermal contact with a heat transfer oil contained in a storage tank. An electrical hot plate simulates the collector/concentrator which heats up the oil circulating in a hollow copper spiral coil thus charging the storage. A model for the collector/concentrator system is developed to enable simulation of the feedforward IMC structure. Using a Simulink block model, the simulation results reveal that a feedforward IMC structure performs better than a feedforward structure. The feedforward IMC structure is tested experimentally and the performance of the control structure is acceptable within a few degrees of the set temperatures. Experimental results are also compared with the simulation results. The simulated responses are found to relate closely to the experimental ones and any discrepancies between the two are discussed. Furthermore, the feedforward IMC structure is also compared experimentally with a combined feedforward and PID feedback structure. Results of the comparison indicate that the feedforward IMC structure performs better than the combined feedforward and PID feedback structure. The thermal profile of the storage during the charging experiment with the feedforward IMC structure is also presented and the results obtained from the storage profile indicate that the storage tank is thermally stratified

Microstructure and Tribological Properties of Mo–40Ni–13Si Multiphase Intermetallic Alloy

Science.gov (United States)

Song, Chunyan; Wang, Shuhuan; Gui, Yongliang; Cheng, Zihao; Ni, Guolong

2016-01-01

Intermetallic compounds are increasingly being expected to be utilized in tribological environments, but to date their implementation is hindered by insufficient ductility at low and medium temperatures. This paper presents a novel multiphase intermetallic alloy with the chemical composition of Mo–40Ni–13Si (at %). Microstructure characterization reveals that a certain amount of ductile Mo phases formed during the solidification process of a ternary Mo–Ni–Si molten alloy, which is beneficial to the improvement of ductility of intermetallic alloys. Tribological properties of the designed alloy—including wear resistance, friction coefficient, and metallic tribological compatibility—were evaluated under dry sliding wear test conditions at room temperature. Results suggest that the multiphase alloy possesses an excellent tribological property, which is attributed to unique microstructural features and thereby a good combination in hardness and ductility. The corresponding wear mechanism is explained by observing the worn surface, subsurface, and wear debris of the alloy, which was found to be soft abrasive wear. PMID:28774106

Microstructure and Tribological Properties of Mo-40Ni-13Si Multiphase Intermetallic Alloy.

Science.gov (United States)

Song, Chunyan; Wang, Shuhuan; Gui, Yongliang; Cheng, Zihao; Ni, Guolong

2016-12-06

Intermetallic compounds are increasingly being expected to be utilized in tribological environments, but to date their implementation is hindered by insufficient ductility at low and medium temperatures. This paper presents a novel multiphase intermetallic alloy with the chemical composition of Mo-40Ni-13Si (at %). Microstructure characterization reveals that a certain amount of ductile Mo phases formed during the solidification process of a ternary Mo-Ni-Si molten alloy, which is beneficial to the improvement of ductility of intermetallic alloys. Tribological properties of the designed alloy-including wear resistance, friction coefficient, and metallic tribological compatibility-were evaluated under dry sliding wear test conditions at room temperature. Results suggest that the multiphase alloy possesses an excellent tribological property, which is attributed to unique microstructural features and thereby a good combination in hardness and ductility. The corresponding wear mechanism is explained by observing the worn surface, subsurface, and wear debris of the alloy, which was found to be soft abrasive wear.

Microstructure and Tribological Properties of Mo–40Ni–13Si Multiphase Intermetallic Alloy

Directory of Open Access Journals (Sweden)

Chunyan Song

2016-12-01

Full Text Available Intermetallic compounds are increasingly being expected to be utilized in tribological environments, but to date their implementation is hindered by insufficient ductility at low and medium temperatures. This paper presents a novel multiphase intermetallic alloy with the chemical composition of Mo–40Ni–13Si (at %. Microstructure characterization reveals that a certain amount of ductile Mo phases formed during the solidification process of a ternary Mo–Ni–Si molten alloy, which is beneficial to the improvement of ductility of intermetallic alloys. Tribological properties of the designed alloy—including wear resistance, friction coefficient, and metallic tribological compatibility—were evaluated under dry sliding wear test conditions at room temperature. Results suggest that the multiphase alloy possesses an excellent tribological property, which is attributed to unique microstructural features and thereby a good combination in hardness and ductility. The corresponding wear mechanism is explained by observing the worn surface, subsurface, and wear debris of the alloy, which was found to be soft abrasive wear.

Soldering Characteristics and Mechanical Properties of Sn-1.0Ag-0.5Cu Solder with Minor Aluminum Addition

Directory of Open Access Journals (Sweden)

Yee Mei Leong

2016-06-01

Full Text Available Driven by the trends towards miniaturization in lead free electronic products, researchers are putting immense efforts to improve the properties and reliabilities of Sn based solders. Recently, much interest has been shown on low silver (Ag content solder SAC105 (Sn-1.0Ag-0.5Cu because of economic reasons and improvement of impact resistance as compared to SAC305 (Sn-3.0Ag-0.5Cu. The present work investigates the effect of minor aluminum (Al addition (0.1–0.5 wt.% to SAC105 on the interfacial structure between solder and copper substrate during reflow. The addition of minor Al promoted formation of small, equiaxed Cu-Al particle, which are identified as Cu3Al2. Cu3Al2 resided at the near surface/edges of the solder and exhibited higher hardness and modulus. Results show that the minor addition of Al does not alter the morphology of the interfacial intermetallic compounds, but they substantially suppress the growth of the interfacial Cu6Sn5 intermetallic compound (IMC after reflow. During isothermal aging, minor alloying Al has reduced the thickness of interfacial Cu6Sn5 IMC but has no significant effect on the thickness of Cu3Sn. It is suggested that of atoms of Al exert their influence by hindering the flow of reacting species at the interface.

Soldering Characteristics and Mechanical Properties of Sn-1.0Ag-0.5Cu Solder with Minor Aluminum Addition

Science.gov (United States)

Leong, Yee Mei; Haseeb, A.S.M.A.

2016-01-01

Driven by the trends towards miniaturization in lead free electronic products, researchers are putting immense efforts to improve the properties and reliabilities of Sn based solders. Recently, much interest has been shown on low silver (Ag) content solder SAC105 (Sn-1.0Ag-0.5Cu) because of economic reasons and improvement of impact resistance as compared to SAC305 (Sn-3.0Ag-0.5Cu. The present work investigates the effect of minor aluminum (Al) addition (0.1–0.5 wt.%) to SAC105 on the interfacial structure between solder and copper substrate during reflow. The addition of minor Al promoted formation of small, equiaxed Cu-Al particle, which are identified as Cu3Al2. Cu3Al2 resided at the near surface/edges of the solder and exhibited higher hardness and modulus. Results show that the minor addition of Al does not alter the morphology of the interfacial intermetallic compounds, but they substantially suppress the growth of the interfacial Cu6Sn5 intermetallic compound (IMC) after reflow. During isothermal aging, minor alloying Al has reduced the thickness of interfacial Cu6Sn5 IMC but has no significant effect on the thickness of Cu3Sn. It is suggested that of atoms of Al exert their influence by hindering the flow of reacting species at the interface. PMID:28773645

Limitaciones del IMC como indicador exclusivo de estado nutricional

Directory of Open Access Journals (Sweden)

Moreno Romero, Susana

2007-01-01

Full Text Available El presente trabajo tiene como objetivo determinar el potencial diagnóstico y las limitaciones del uso del Índice de Masa Corporal como único indicador del estado nutricional. Para ello se analizó una muestra constituida por 2155 sujetos de ambos sexos, con edades comprendidas entre los 6 y 18 años y pertenecientes a tres poblaciones jujeñas que difieren en ubicación altitudinal y nivel socieconómico (NSE: 1. Susques, localidad rural situada a 3675 m.s.n.m; 2. Alto Comedero, barrio periférico de San Salvador de Jujuy (1250 m.s.n.m. de NSE bajo; y 3. José Hernández, muestra representativa del estrato SE elevado de la misma capital. Se tomaron las medidas directas de talla, peso, perímetro braquial y pliegues de grasa subcutánea tricipital y subescapular, entre otras. A partir de éstas, se calculó el IMC y las áreas tisulares del brazo. Se establecieron las categorías nutricionales en función de los percentilos establecidos por el NHANES I y II para la talla, IMC, área magra y grasa del brazo y pliegues tricipital y subescapular. Al comparar los resultados obtenidos para cada variable se comprueba como el uso exclusivo del IMC enmascara importantes patologías nutricionales, tanto por defecto como por exceso.

Fatigue of superalloys and intermetallics

International Nuclear Information System (INIS)

Stoloff, N.S.

1993-01-01

The fatigue behavior of intermetallic alloys and their composites is contrasted to that of nickel-base superalloys. The roles of microstructure and slip planarity are emphasized. Obstacles to use of intermetallics under cyclic loading conditions are described and future research directions are suggested

Calorimetric investigations of UPb{sub 3} compound

Energy Technology Data Exchange (ETDEWEB)

Agarwal, Renu, E-mail: arenu@barc.gov.in; Samui, Pradeep; Mukerjee, S.K.

2016-08-10

Highlights: • First time reporting of enthalpy increment and heat capacity data of UPb{sub 3} compound. • First time reporting of high temperature calorimetric determination of enthalpy of formation of UPb{sub 3} compound. • Miedema model was used to calculate enthalpies of formation of UPb{sub 3} and UPb. • Thermodynamic table of the compound UPb{sub 3} was generated. - Abstract: Interaction of uranium based metallic fuels and lead coolant can lead to formation of intermetallic compounds of U-Pb system. To understand U-Pb interactions, it is important to know thermodynamic properties of intermetallic compounds present in this system, UPb{sub 3} and UPb. In the present work, enthalpy increment, heat capacity and enthalpy of formation of UPb{sub 3} intermetallic compound were determined. The enthalpy increment was determined by high temperature Calvet calorimeter and heat capacity was determined using DSC. The heat capacity data was used to calculate thermodynamic parameters of the compound as a function of temperature. The enthalpy of formation at 843 K was determined using successive precipitation method, by direct reaction calorimetry. The enthalpy of formation at 843 K, from Pb(l) and U(l), was −28.9 kJ at-mol{sup −1} and after adjusting enthalpy increments of pure elements and compound, the enthalpy of formation of the compound at 298 K, from Pb(s) and U(α) was found to be −20.0 kJ at-mol{sup −1}.

Magnetic, transport and magnetocaloric properties in the Laves phase intermetallic Ho (Co1−xAlx)2 compounds

International Nuclear Information System (INIS)

Ivanova, T.I.; Nikitin, S.A.; Tskhadadze, G.A.; Koshkid’ko, Yu.S.; Suski, W.; Iwasieczko, W.; Badurski, D.

2014-01-01

Highlights: • The Al influence on magnetic properties of the Ho (Co 1-x Al x ) 2 compounds is analyzed. • The first-order magnetic transition appears in sample with Al concentrations x ≤ 0.06. • The MCE and Curie temperature TC demonstrate complex Al concentration dependences. • The magnetoresistance for sample with Al concentration x = 0.06 (58%) is maximum. • High magnetic fields changes the Curie temperature T c of the Ho (Co 1−x Al x ) 2 compounds. - Abstract: The magnetization, magnetoresistivity and magnetocaloric effect (MCE) of the Ho (Co 1−x Al x ) 2 Laves phase intermetallic compounds for x ⩽ 0.2 have been investigated. Complex measurements have been carried out in order to determine the influence of substitution in the Co sublattice by Al on the Co moment, type of the magnetic transition and related properties of these compounds. A comparative analysis of the magnetic, transport and magnetocaloric properties of Ho (Co 1−x Al x ) 2 alloys under various Al concentration is represented. Substitutions at the Co site by Al are found to result in the appearance of itinerant electron metamagnetism (IEM) at the small Al concentrations and in positive magnetovolume effect, leading to an initial increase in the ordering temperature; on the other hand the magnetic phase transition temperature as well as ΔT (MCE) do not depend in direct way on the Al concentration. The 16% increase of magnetocaloric effect for the alloy with x = 0.02 is detected in relation to maternal HoCo 2 . A giant value of magnetoresistivity (58%) is observed for the alloy with the same Al concentration

Effect of Joint Scale and Processing on the Fracture of Sn-3Ag-0.5Cu Solder Joints: Application to Micro-bumps in 3D Packages

Science.gov (United States)

Talebanpour, B.; Huang, Z.; Chen, Z.; Dutta, I.

2016-01-01

In 3-dimensional (3D) packages, a stack of dies is vertically connected to each other using through-silicon vias and very thin solder micro-bumps. The thinness of the micro-bumps results in joints with a very high volumetric proportion of intermetallic compounds (IMCs), rendering them much more brittle compared to conventional joints. Because of this, the reliability of micro-bumps, and the dependence thereof on the proportion of IMC in the joint, is of substantial concern. In this paper, the growth kinetics of IMCs in thin Sn-3Ag-0.5Cu joints attached to Cu substrates were analyzed, and empirical kinetic laws for the growth of Cu6Sn5 and Cu3Sn in thin joints were obtained. Modified compact mixed mode fracture mechanics samples, with adhesive solder joints between massive Cu substrates, having similar thickness and IMC content as actual micro-bumps, were produced. The effects of IMC proportion and strain rate on fracture toughness and mechanisms were investigated. It was found that the fracture toughness G C decreased with decreasing joint thickness ( h Joint). In addition, the fracture toughness decreased with increasing strain rate. Aging also promoted alternation of the crack path between the two joint-substrate interfaces, possibly proffering a mechanism to enhance fracture toughness.

Intermetallics Synthesis in the Fe–Al System via Layer by Layer 3D Laser Cladding

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Floran Missemer

2013-10-01

Full Text Available Intermetallide phase formation was studied in a powdered Fe–Al system under layer by layer laser cladding with the aim of fabricating the gradient of properties by means of changing the Fe–Al concentration ratio in the powder mixture from layer to layer. The relationships between the laser cladding parameters and the intermetallic phase structures in the consecutively cladded layers were determined. In order to study the structure formation an optical microscopy, X-ray diffraction analysis, measurement of microhardness, scanning electron microscopy (SEM with energy dispersive X-ray (EDX spectroscopy analysis were used after the laser synthesis of intermetallic compounds.

Influence of interstitial solutions (H, N) on cerium electronic state in Ce-Fe intermetallic compounds: X-ray Absorption Spectroscopy (XAS) study

International Nuclear Information System (INIS)

Chaboy, J.; Marcelli, A.; Bozukov, L.

1995-03-01

It is presented an x-ray absorption spectroscopy (XAS) investigation performed at the L-edges of the rare-earth and at the K-edge of iron in the R-Fe intermetallic compounds (La, Ce) 2 Fe 14 BH χ and Ce 2 Fe 17 (H,N) χ , to elucidate the role of the interstitial doping into the electronic and magnetic properties of these systems. Comparison with x-ray circular magnetic dichroism (XCMD) experiments has been carried out to clarify the localization of 4f magnetic moment at the Ce sites upon hydriding. Both XAS and XCMD results evidence the interplay between the structural and magnetic changes, that are associated to the modification of the hybridization between the Fe(3d) and Ce(5d) bands

Method to increase the transition temperature and for the critical magnetic field strength of the known intermetallic compounds of vanadium or niobium

International Nuclear Information System (INIS)

Winter, H.

1977-01-01

The invention deals with a method to raise the transition temperature and critical magnetic field strength of superconducting, intermetallic compounds of vanadium and niobium. For example, a niobium alloy with 4 wt.% Al in melted in vacuum electric arc and formed into a sheet of about 1 mm thick. Strips of this sheet are electrically heated up to 1,900 0 C for one hour in a high-vacuum oven. The strips are then annealed in evacuated quartz ampoules for 120 hours at 800 0 C. These strips have a transition temperature of 24 K and a critical magnetic field strength of 600 kg; the critical current density was 5 x 10 4 A/cm 2 . (HPOE) [de

Synthesis and reactivity of single-phase Be{sub 17}Ti{sub 2} intermetallic compounds

Energy Technology Data Exchange (ETDEWEB)

Kim, Jae-Hwan, E-mail: kim.jaehwan@jaea.go.jp [Breeding Functional Materials Development Group, Sector of Fusion Research and Development, Japan Atomic Energy Agency (Japan); Iwakiri, Hirotomo; Furugen, Tatsuaki [Faculty of Education Elementary and Secondary School Teacher Training Program, University of the Ryukyus, Okinawa (Japan); Nakamichi, Masaru [Breeding Functional Materials Development Group, Sector of Fusion Research and Development, Japan Atomic Energy Agency (Japan)

2016-01-15

Highlights: • Preliminary synthesis of single-phase Be{sub 17}Ti{sub 2} was succeeded. • Reactivity difference between beryllium and beryllides may be caused by a lattice strain. • Oxidation of Be{sub 17}Ti{sub 2} at high temperatures results in the formation of TiO{sub 2}. • Simulation results reveal that a stable site for hydrogen at the center of tetrahedron exists. - Abstract: To investigate feasibility for application of Be{sub 17}Ti{sub 2} as a neutron multiplier as well as a refractory material, single-phase Be{sub 17}Ti{sub 2} intermetallic compounds were synthesized using an annealing heat treatment of the starting powder and a plasma sintering method. Scanning electron microscopic observations and X-ray diffraction measurements reveal that the single-phase Be{sub 17}Ti{sub 2} compounds were successfully synthesized. We examined the reactivity of Be{sub 17}Ti{sub 2} with 1% H{sub 2}O and discovered that a larger stoichiometric amount of Ti resulted in the formation of TiO{sub 2} on the surface at high temperatures. This oxidation may also contribute to an increase in both weight gain and generation of H{sub 2}. This suggests that the formation of the Ti-depleted Be{sub 17}Ti{sub 2−x} layer as a result of oxidation facilitates an increased reactivity with H{sub 2}O. To evaluate the safety aspects of Be{sub 17}Ti{sub 2}, we also investigated the hydrogen positions and solution energies based on the first principle. The calculations reveal that there are 10 theoretical sites, where 9 of these sites have hydrogen solution energies with a positive value (endothermic) and 1 site located at the center of a tetrahedron comprising two Be and two Ti atoms gives a negative value (exothermic).

Sintered cobalt-rare earth intermetallic product

International Nuclear Information System (INIS)

Benz, M.C.

1975-01-01

A process is described for preparing novel sintered cobalt--rare earth intermetallic products which can be magnetized to form permanent magnets having stable improved magnetic properties. A cobalt--rare earth metal alloy is formed having a composition which at sintering temperature falls outside the composition covered by the single Co 5 R intermetallic phase on the rare earth richer side. The alloy contains a major amount of the Co 5 R intermetallic phase and a second solid CoR phase which is richer in rare earth metal content than the Co 5 R phase. The specific cobalt and rare earth metal content of the alloy is substantially the same as that desired in the sintered product. The alloy, in particulate form, is pressed into compacts and sintered to the desired density. The sintered product is comprised of a major amount of the Co 5 R solid intermetallic phase and up to about 35 percent of the product of the second solid CoR intermetallic phase which is richer in rare earth metal content than the Co 5 R phase

Rare earth-ruthenium-magnesium intermetallics

Energy Technology Data Exchange (ETDEWEB)

Stein, Sebastian; Kersting, Marcel; Heletta, Lukas; Poettgen, Rainer [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie

2017-07-01

Eight new intermetallic rare earth-ruthenium-magnesium compounds have been synthesized from the elements in sealed niobium ampoules using different annealing sequences in muffle furnaces. The compounds have been characterized by powder and single crystal X-ray diffraction. Sm{sub 9.2}Ru{sub 6}Mg{sub 17.8} (a=939.6(2), c=1779(1) pm), Gd{sub 11}Ru{sub 6}Mg{sub 16} (a=951.9(2), c=1756.8(8) pm), and Tb{sub 10.5}Ru{sub 6}Mg{sub 16.5} (a=942.5(1), c=1758.3(4) pm) crystallize with the tetragonal Nd{sub 9.34}Ru{sub 6}Mg{sub 17.66} type structure, space group I4/mmm. This structure exhibits a complex condensation pattern of square-prisms and square-antiprisms around the magnesium and ruthenium atoms, respectively. Y{sub 2}RuMg{sub 2} (a=344.0(1), c=2019(1) pm) and Tb{sub 2}RuMg{sub 2} (a=341.43(6), c=2054.2(7) pm) adopt the Er{sub 2}RuMg{sub 2} structure and Tm{sub 3}Ru{sub 2}Mg (a=337.72(9), c=1129.8(4) pm) is isotypic with Sc{sub 3}Ru{sub 2}Mg. Tm{sub 3}Ru{sub 2}Mg{sub 2} (a=337.35(9), c=2671(1) pm) and Lu{sub 3}Ru{sub 2}Mg{sub 2} (a=335.83(5), c=2652.2(5) pm) are the first ternary ordered variants of the Ti{sub 3}Cu{sub 4} type, space group I4/mmm. These five compounds belong to a large family of intermetallics which are completely ordered superstructures of the bcc subcell. The group-subgroup scheme for Lu{sub 3}Ru{sub 2}Mg{sub 2} is presented. The common structural motif of all three structure types are ruthenium-centered rare earth cubes reminicent of the CsCl type. Magnetic susceptibility measurements of Y{sub 2}RuMg{sub 2} and Lu{sub 3}Ru{sub 2}Mg{sub 2} samples revealed Pauli paramagnetism of the conduction electrons.

Aktivitas Komunikasi Pemasaran Terpadu (IMC Pemerintah Kota Ambon dalam Mengkomunikasikan Brand “Ambon City Of Music” Melalui Kegiatan Tiga Pilar IMC

Directory of Open Access Journals (Sweden)

Arthur Solsolay

2016-07-01

Full Text Available Ambon city is one of the tourist destinations in the province of Maluku, kept the charm and appeal of natural, historical, religious, culinary, education, art, culture and customs. To develop and trigger the development of musical art in the city of Ambon, Ambon city government felt the need to form a brand that became a brand differentiator and became icons of tourism in Ambon. Brand "Ambon City of Music" was initiated in hopes of becoming a starting point for the development of city Ambon become more competitive through an integrated marketing communications activities in brand communication. Research to describe and analyze the concept of the three pillars of IMC in the steps taken by the Government of Ambon in communicating the brand "Ambon City of Music". other research method used is descriptive qualitative case study approach. R esearchers found that the government has made strategic moves in IMC pillar concept is to approach audiences (government, private sector / stakeholder, elements of the community and the media (elements of the marketing communication mix.

Influence of Zn Interlayer on Interfacial Microstructure and Mechanical Properties of TIG Lap-Welded Mg/Al Joints

Science.gov (United States)

Gao, Qiong; Wang, Kehong

2016-03-01

This study explored 6061 Al alloy and AZ31B Mg alloy joined by TIG lap welding with Zn foils of varying thicknesses, with the additional Zn element being imported into the fusion zone to alloy the weld seam. The microstructures and chemical composition in the fusion zone near the Mg substrate were examined by SEM and EDS, and tensile shear strength tests were conducted to investigate the mechanical properties of the Al/Mg joints, as well as the fracture surfaces, and phase compositions. The results revealed that the introduction of an appropriate amount of Zn transition layer improves the microstructure of Mg/Al joints and effectively reduces the formation of Mg-Al intermetallic compounds (IMCs). The most common IMCs in the fusion zone near the Mg substrate were Mg-Zn and Mg-Al-Zn IMCs. The type and distribution of IMCs generated in the weld zone differed according to Zn additions; Zn interlayer thickness of 0.4 mm improved the sample's mechanical properties considerably compared to thicknesses of less than 0.4 mm; however, any further increase in Zn interlayer thickness of above 0.4 mm caused mechanical properties to deteriorate.

Electrical characteristics for Sn-Ag-Cu solder bump with Ti/Ni/Cu under-bump metallization after temperature cycling tests

Science.gov (United States)

Shih, T. I.; Lin, Y. C.; Duh, J. G.; Hsu, Tom

2006-10-01

Lead-free solder bumps have been widely used in current flip-chip technology (FCT) due to environmental issues. Solder joints after temperature cycling tests were employed to investigate the interfacial reaction between the Ti/Ni/Cu under-bump metallization and Sn-Ag-Cu solders. The interfacial morphology and quantitative analysis of the intermetallic compounds (IMCs) were obtained by electron probe microanalysis (EPMA) and field emission electron probe microanalysis (FE-EPMA). Various types of IMCs such as (Cu1-x,Agx)6Sn5, (Cu1-y,Agy)3Sn, and (Ag1-z,Cuz)3Sn were observed. In addition to conventional I-V measurements by a special sample preparation technique, a scanning electron microscope (SEM) internal probing system was introduced to evaluate the electrical characteristics in the IMCs after various test conditions. The electrical data would be correlated to microstructural evolution due to the interfacial reaction between the solder and under-bump metallurgy (UBM). This study demonstrated the successful employment of an internal nanoprobing approach, which would help further understanding of the electrical behavior within an IMC layer in the solder/UBM assembly.

Intermetallics as innovative CRM-free materials

Science.gov (United States)

Novák, Pavel; Jaworska, Lucyna; Cabibbo, Marcello

2018-03-01

Many of currently used technical materials cannot be imagined without the use of critical raw materials. They require chromium (e.g. in stainless and tool steels), tungsten and cobalt (tool materials, heat resistant alloys), niobium (steels and modern biomaterials). Therefore there is a need to find substitutes to help the European economy. A promising solution can be the application of intermetallics. These materials offer wide variety of interesting properties, such as high hardness and wear resistance or high chemical resistance. In this paper, the overview of possible substitute materials among intermetallics is presented. Intermetallics based on aluminides and silicides are shown as corrosion resistant materials, composites composed of ceramics in intermetallic matrix as possible tool materials. The manufacturing processes are being developed to minimize the disadvantages of these materials, mainly the room-temperature brittleness.

Electronic structure and properties of rare earth and actinide intermetallics

International Nuclear Information System (INIS)

Kirchmayr, H.R.

1984-01-01

There are 188 contributions, experimental and theoretical, a few on rare earth and actinide elements but mostly on rare earth and actinide intermetallic compounds and alloys. The properties dealt with include 1) crystal structure, 2) magnetic properties and magnetic structure, 3) magnetic phase transformations and valence fluctuations, 4) electrical properties and superconductivity and their temperature, pressure and magnetic field dependence. A few papers deal with crystal growth and novel measuring methods. (G.Q.)

Atomistic simulation of radiation-induced amorphization of the B2 ordered intermetallic compound NiTi

International Nuclear Information System (INIS)

Sabochick, M.J.

1990-12-01

Amorphization of the B2 intermetallic compound NiTi under electron irradiation has been investigated using molecular dynamics. The effect of irradiation was simulated using two processes: (1) Ni and Ti atoms were exchanged, resulting in chemical disorder, and (2) Frenkel pairs were introduced, leading to the formation of stable point defects and also chemical disorder upon mutual recombination of interstitials and vacancies. After ∼0.4 exchanges per atom, the first process resulted in an energy increase of approximately 0.11 eV/atom and a volume increase of 1.91%. On the other hand, after introducing ∼0.5 Frenkel pairs per atom, the second process led to smaller increases of 0.092 eV/atom in energy and 1.43% in volume. The calculated radial distribution functions (RDFs) were essentially identical to each other and to the calculated RDF of a quenched liquid. The structure factor, however, showed that long-range order was still present after atom exchanges, while the introduction of Frenkel pairs resulted in the loss of long-range order. It was concluded that point defects are necessary for amorphization to occur in NiTi, although chemical disorder alone is capable of storing enough energy to make the transition possible. 18 refs., 3 figs

International dimensions of the IMC

Directory of Open Access Journals (Sweden)

Bešlin Marija

2005-01-01

Full Text Available Seems that one of the basic challenge facing marketing organizations today related to shift from traditional functions and operations to the new pattern of the 21st century and the global marketplace. The old traditional models are less and less relevant growing tendency of world market's complexity and increasing competitive efforts ask for "fresh approach" and types of communication with the consumers and other stakeholders. Accordingly, the traditional (linear model have to be replaced with IMC integrated and interactive marketing communication. Shift toward integrated marketing communications is one of the most significant marketing communication development occurred during the 1990s and such direction is continuing in the new century or time to come.

Rare-earth transition-metal intermetallics: Structure-bonding-property relationships

Energy Technology Data Exchange (ETDEWEB)

Han, M. K. [Iowa State Univ., Ames, IA (United States)

2006-01-01

The explorations of rare-earth, transition metal intermetallics have resulted in the synthesis and characterization, and electronic structure investigation, as well as understanding the structure-bonding property relationships. The work has presented the following results: (1) Understanding the relationship between compositions and properties in LaFe_13-xSi_x system: A detailed structural and theoretical investigation provided the understanding of the role of a third element on stabilizing the structure and controlling the transformation of cubic NaZn{sub 13}-type structures to the tetragonal derivative, as well as the relationship between the structures and properties. (2) Synthesis of new ternary rare-earth iron silicides Re_2-xFe₄Si_14-y and proposed superstructure: This compound offers complex structural challenges such as fractional occupancies and their ordering in superstructure. (3) Electronic structure calculation of FeSi₂: This shows that the metal-semiconductor phase transition depends on the structure. The mechanism of band gap opening is described in terms of bonding and structural distortion. This result shows that the electronic structure calculations are an essential tool for understanding the relationship between structure and chemical bonding in these compounds. (4) Synthesis of new ternary rare-earth Zinc aluminides Tb₃Zn_3.6Al_7.4: Partially ordered structure of Tb₃Zn_3.6Al_7.4 compound provides new insights into the formation, composition and structure of rare-earth transition-metal intermetallics. Electronic structure calculations attribute the observed composition to optimizing metal-metal bonding in the electronegative (Zn, Al) framework, while the specific ordering is strongly influenced by specific orbital interactions. (5) Synthesis of new structure type of Zn₃₉(Cr_xAl_1-x)₈₁

Rare-Earth Transition-Metal Intermetallics: Structure-bonding-Property Relationships

Energy Technology Data Exchange (ETDEWEB)

Han, Mi-Kyung [Iowa State Univ., Ames, IA (United States)

2006-01-01

Our explorations of rare-earth, transition metal intermetallics have resulted in the synthesis and characterization, and electronic structure investigation, as well as understanding the structure-bonding-property relationships. Our work has presented the following results: (1) Understanding the relationship between compositions and properties in LaFe_13-xSi_x system: A detailed structural and theoretical investigation provided the understanding of the role of a third element on stabilizing the structure and controlling the transformation of cubic NaZn₁₃-type structures to the tetragonal derivative, as well as the relationship between the structures and properties. (2) Synthesis of new ternary rare-earth iron silicides RE_2-xFe₄Si_14-y and proposed superstructure: This compound offers complex structural challenges such as fractional occupancies and their ordering in superstructure. (3) Electronic structure calculation of FeSi₂: This shows that the metal-semiconductor phase transition depends on the structure. The mechanism of band gap opening is described in terms of bonding and structural distortion. This result shows that the electronic structure calculations are an essential tool for understanding the relationship between structure and chemical bonding in these compounds. (4) Synthesis of new ternary rare-earth Zinc aluminides Tb₃Zn_3.6Al_7.4: Partially ordered structure of Tb_3.6Zn_13-xAl_7.4 compound provides new insights into the formation, composition and structure of rare-earth transition-metal intermetallics. Electronic structure calculations attribute the observed composition to optimizing metal-metal bonding in the electronegative (Zn, Al) framework, while the specific ordering is strongly influenced by specific orbital interactions. (5) Synthesis of new structure type of Zn₃₉(Cr_xAl_1-x

Intermetallic Growth and Interfacial Properties of the Grain Refiners in Al Alloys

Science.gov (United States)

Li, Chunmei; Cheng, Nanpu; Chen, Zhiqian; Xie, Zhongjing; Hui, Liangliang

2018-01-01

Al3TM(TM = Ti, Zr, Hf, Sc) particles acting as effective grain refiners for Al alloys have been receiving extensive attention these days. In order to judge their nucleation behaviors, first-principles calculations are used to investigate their intermetallic and interfacial properties. Based on energy analysis, Al3Zr and Al3Sc are more suitable for use as grain refiners than the other two intermetallic compounds. Interfacial properties show that Al/Al3TM(TM = Ti, Zr, Hf, Sc) interfaces in I-ter interfacial mode exhibit better interface wetting effects due to larger Griffith rupture work and a smaller interface energy. Among these, Al/Al3Sc achieves the lowest interfacial energy, which shows that Sc atoms should get priority for occupying interfacial sites. Additionally, Sc-doped Al/Al3(Zr, Sc) interfacial properties show that Sc can effectively improve the Al/Al3(Zr, Sc) binding strength with the Al matrix. By combining the characteristics of interfaces with the properties of intermetallics, the core-shell structure with Al3Zr-core or Al3Zr(Sc1-1)-core encircled with an Sc-rich shell forms. PMID:29677155

Computer simulation of disordering kinetics in irradiated A3B intermetallic compounds

International Nuclear Information System (INIS)

Spaczer, M.; Caro, A.; Victoria, M.; De la Rubia, T.

1994-01-01

Molecular dynamics computer simulations of collision cascades on intermetallic Ni 3 Al, Cu 3 Au and NiAl have been performed to study the nature of the disordering processes in the cascade. The evolution of the crystalline and chemical order parameters show different time scales. To understand these features we study the liquid phase of these three alloys and present simulation results concerning the dynamical melting of small samples, examining the relaxation time and saturation value of the chemical short range order, SRO. A theoretical model for the time evolution of the SRO is given. ((orig.))

Formation of Ni-Ti intermetallics during reactive sintering at 500-650 degrees C

Czech Academy of Sciences Publication Activity Database

Novák, P.; Pokorný, P.; Vojtěch, V.; Knaislová, A.; Školáková, A.; Čapek, J.; Karlík, M.; Kopeček, Jaromír

2015-01-01

Roč. 155, Apr (2015), s. 113-121 ISSN 0254-0584 R&D Projects: GA ČR(CZ) GA14-03044S Institutional support: RVO:68378271 Keywords : intermetallic compounds * powder metallurgy * electron microscopy * microstructure Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 2.101, year: 2015

Learning Through Media; An IMC Handbook for Chelmsford Teachers.

Science.gov (United States)

Morrow, James; Wallace, Daniel

This handbook is designed to provide basic information that is necessary to use the Chelmsford School System's Instructional Media Center (IMC). It defines six different media (print, sound, television, photography, movies and design) and suggests a series of separate classroom production activities in each. An emphasis is given to the ways in…

Sintered cobalt-rare earth intermetallic product

International Nuclear Information System (INIS)

Benz, M.G.

1975-01-01

This patent describes a sintered product having substantially stable permanent magnet properties in air at room temperature. It comprises compacted particulate cobalt--rare earth alloy consisting essentially of a Co 5 R intermetallic phase and a CoR intermetallic phase which is richer in rare earth metal content than the Co 5 R phase, where R is a rare earth metal. The Co 5 R intermetallic phase is present in an amount of at least 65 percent by weight of the sintered product and the CoR intermetallic phase which is richer in rare earth metal content than the Co 5 R phase is present in a positive amount having a value ranging up to about 35 percent by weight of the product. The sintered product has a density of at least 87 percent and has pores which are substantially noninterconnecting and wherein the component grains have an average size less than 30 microns

Tsuwalhkalh Ti Tmicwa (The Land is Ours): Stat'imc Self-Determination in the Face of Large-Scale Hydro-electric Development

Science.gov (United States)

Moritz, Sarah Carmen

In Canada, First Nations asserting authority over their lands are developing diverse strategies to overcome the state''s dogmatic insistence on jurisdictional sovereignty. This movement corresponds to the wider context of the challenges faced by indigenous people to use their own ways of knowing to resist or reformulate legal doctrines and political tenets based on colonial power. Interior Salish Stat'imc people identify themselves through a strong and ongoing social relationship with Sataqwa7, the Fraser River, and the "Valley of Plenty"---now known as the flooded Bridge River Valley---maintained through Stat'imc knowledge and cultural practice and demonstrated by talk of '"the Stat'imc right to fish" and Tsuwalhkalh Ti Tmicwa (The Land is Ours). Stat'imc fishers are prepared to contest and resist any regulatory system that is understood to impact this right to fish while they advocate their own ways of sustainable fishing and water management. Based on ethnographic research in collaboration with Stat'imc people, this thesis explores some of these often successful contestations especially in the context of increasing territorial governance and by example of the rapidly transforming relationship between Stat'imc, BC Hydro and the Province of BC. Interior Salish Stat'imc people are currently navigating through a significant phase of increasing jurisdiction and authority and recognition of (unsettled) territorial property relationships. This very dynamic process is marked by strategic collaborations, compensation for 'infringements' on St'a'imc Title and Rights, and conservation efforts to protect their home. An important example is the changing relationship between Stat'imc people and BC Hydro---a relationship between two groups with radically different cultures and agendas: Stat'imc people in a struggle for self-determination, social justice and cultural survival and BC Hydro, a corporate culture, with the agenda to provide hydro-electric power to BC, maintain

A study of atomic distribution in the intermetallic compound by AP-FIM

International Nuclear Information System (INIS)

Ren, D.G.

1993-01-01

This paper reports a study of the atomic distributions in the intermetallic compound by field ion microscope and atom probe (AP-FIM). The samples used in this work had nearly stoichiometry composition of Ni 3 Al with boron and without boron. The samples of TiAl also had nearly stoichiometry composition and adding Zr and Mn. The field ion image of Ni 3 Al without boron displays essentially the ordered f.c.c. crystal structure (Ll 2 ) with the center of (001) face. The field ion image of B-doped Ni 3 Al shows that the extent of ordering is reduced by addition of boron. The results of AP analysis show that the distribution of boron atom in Ni 3 Al is approximately homogeneous for the low boron contents. The atomic arrangements of Ni and Al in Ni 3 Al crystal lattice were changed by addition of boron. It is shown in the probability of consecutive evaporative sequence Al-Al and Ni-Ni is increased with B-doping. The field ion image of TiAl shows two regions with ordered f.c.t crystal structure (r-TiAl) and disordered. The distributions of Ti and Al atoms in the TiAl alloy show that the structure of a lamellar mixture were confirmed by AP profiles. The results of AP analysis show that distributions of Ti, Al, Mn and Zr in the alloy essentially is homogeneous. The results of AP analysis also exhibit that the interface of an oxide exists in the alloys. These interfaces of oxides consist of TiO and AlO in the TiAl, NiO in the Ni 3 Al. The broadness of the oxides interface were estimated about 8-10nm

Plasticity enhancement mechanisms in refractory metals and intermetallics

International Nuclear Information System (INIS)

Gibala, R.; Chang, H.; Czarnik, C.M.; Edwards, K.M.; Misra, A.

1993-01-01

Plasticity enhancement associated with surface films and precipitates or dispersoids in bcc refractory metals is operative in ordered intermetallic compounds. Some results are given for NiAl and MoSi 2 -based materials. The monotonic and cyclic plasticity of NiAl at room temperature can be enhanced by surface films. Ductile second phases also enhance the plasticity of NiAl. MoSi 2 exhibits similar effects of surface films and dispersoids, but primarily at elevated temperatures. The plasticity enhancement is associated with enhanced dislocation generation from constrained deformation at the film-substrate or precipitate/dispersoid-matrix interface of the composite systems

The Effectiveness of Al-Si Coatings for Preventing Interfacial Reaction in Al-Mg Dissimilar Metal Welding

Science.gov (United States)

Wang, Yin; Al-Zubaidy, Basem; Prangnell, Philip B.

2018-01-01

The dissimilar welding of aluminum to magnesium is challenging because of the rapid formation of brittle intermetallic compounds (IMC) at the weld interface. An Al-Si coating interlayer was selected to address this problem, based on thermodynamic calculations which predicted that silicon would change the reaction path to avoid formation of the normally observed binary Al-Mg IMC phases ( β-Al3Mg2 and γ-Al12Mg17). Long-term static heat treatments confirmed that a Si-rich coating will preferentially produce the Mg2Si phase in competition with the less stable, β-Al3Mg2 and γ-Al12Mg17 binary IMC phases, and this reduced the overall reaction layer thickness. However, when an Al-Si clad sheet was tested in a real welding scenario, using the Refill™ friction stir spot welding (FSSW) technique, Mg2Si was only produced in very small amounts owing to the much shorter reaction time. Surprisingly, the coating still led to a significant reduction in the IMC reaction layer thickness and the welds exhibited enhanced mechanical performance, with improved strength and fracture energy. This beneficial behavior has been attributed to the softer coating material both reducing the welding temperature and giving rise to the incorporation of Si particles into the reaction layer, which toughened the brittle interfacial IMC phases during crack propagation.

Effects of Ni{sub 3}Sn{sub 4} and (Cu,Ni){sub 6}Sn{sub 5} intermetallic layers on cross-interaction between Pd and Ni in solder joints

Energy Technology Data Exchange (ETDEWEB)

Baek, Yong-Ho [Department of Materials Science and Engineering, Korea University, Seoul 136-713 (Korea, Republic of); Division of Advanced Circuit Interconnect, Samsung Electro-Mechanics Co., Ltd., Suwon 443-743 (Korea, Republic of); Chung, Bo-Mook [Department of Materials Science and Engineering, Korea University, Seoul 136-713 (Korea, Republic of); Department of Research and Development, KPM TECH, Ansan 425-090 (Korea, Republic of); Choi, Young-Sik [Division of Advanced Circuit Interconnect, Samsung Electro-Mechanics Co., Ltd., Suwon 443-743 (Korea, Republic of); Choi, Jaeho [Department of Advanced Metal and Materials Engineering, Gangneung-Wonju National University, Gangneung 210-702 (Korea, Republic of); Huh, Joo-Youl, E-mail: jyhuh@korea.ac.kr [Department of Materials Science and Engineering, Korea University, Seoul 136-713 (Korea, Republic of)

2013-12-05

Highlights: •Ni{sub 3}Sn{sub 4} acts as a source of Ni atoms, leading to a strong cross-interaction with Pd. •(Cu,Ni){sub 6}Sn{sub 5} is an effective Ni diffusion barrier, inhibiting Pd resettlement. •Dissolution kinetics of (Pd,Ni)Sn{sub 4} was interpreted based on the Sn–Ni–Pd isotherm. •Cu addition to solder alleviates the (Pd,Ni)Sn{sub 4}-related risk of reliability deterioration. -- Abstract: We examined the effects of layers of intermetallic compound (IMC) Ni{sub 3}Sn{sub 4} and (Cu,Ni){sub 6}Sn{sub 5} formed at the solder/Ni interface, on the cross-interactions between Pd and Ni during solid-state aging and reflow soldering. Two types of diffusion couples, Pd/Sn/Ni and Pd/Sn–Cu/Ni, were aged at 150 °C to study the solid-state interactions. In contrast to the Pd/Sn/Ni couples in which a Ni{sub 3}Sn{sub 4} layer formed at the Ni interface, the Pd/Sn–Cu/Ni couple where a (Cu,Ni){sub 6}Sn{sub 5} layer formed at the Ni interface exhibited no significant interaction between Pd and Ni. The (Cu,Ni){sub 6}Sn{sub 5} layer acted as an effective barrier against Ni diffusion and thus inhibited the resettlement of (Pd,Ni)Sn{sub 4} onto the Ni interface. For the interaction during reflow, Sn–3.5Ag and Sn–3.0Ag–0.5Cu solder balls were isothermally reflowed on an electroless Ni(P)/electroless Pd/immersion Au (ENEPIG) surface finish at 250 °C, and the dissolution kinetics of the (Pd,Ni)Sn{sub 4} particles converted from the 0.2-μm-thick Pd-finish layer were examined. The spalled (Pd,Ni)Sn{sub 4} particles very quickly dissolved into the molten solder when the IMC layer formed on the Ni substrate was (Cu,Ni){sub 6}Sn{sub 5} rather than Ni{sub 3}Sn{sub 4}. The dependence of the dissolution kinetics of the spalled (Pd,Ni)Sn{sub 4} particles on the IMC layers was rationalized on the basis of a Sn–Ni–Pd isotherm at 250 °C. The present study suggests that the formation of a dense (Cu,Ni){sub 6}Sn{sub 5} layer at the solder/Ni interface can effectively

Effect of intermetallic precipitation on the properties of multi passed duplex stainless steel weldment

Energy Technology Data Exchange (ETDEWEB)

Bae, Seong Han [Technology research institute, Ulsan (Korea, Republic of); Lee, Hae Woo [Dong-A University, Busan (Korea, Republic of)

2014-01-15

This study investigated the effect of the aging time of weldment of 24Cr-3.5Mo duplex stainless steel on the microstructure and corrosion behavior. After performing FCAW, we carried out heat treatments at varying times at 850 ℃ and performed observation of microstructure, potentio dynamic test, SEM-EDS analysis, and X-ray diffraction analysis. As the aging time increased, the fraction of δ-ferrite decreased sharply, but the fraction of γ slightly increased. The σ phase was generated at a non-metallic inclusion along the grain boundaries of δ-ferrite and γ, while the χ phase was generated in the structure of δ-ferrite. As the intermetallic compounds increased, the critical pitting potential fell sharply, and PREN of the surrounding structure decreased by 5 due to precipitation of the σ phase in 3.5% NaCl at 60 ℃. Pitting occurred intensively under a multi-pass line which relatively had more intermetallic compounds, and the precipitation of the σ phase caused the formation of Cr carbide.

Effect of intermetallic precipitation on the properties of multi passed duplex stainless steel weldment

International Nuclear Information System (INIS)

Bae, Seong Han; Lee, Hae Woo

2014-01-01

This study investigated the effect of the aging time of weldment of 24Cr-3.5Mo duplex stainless steel on the microstructure and corrosion behavior. After performing FCAW, we carried out heat treatments at varying times at 850 ℃ and performed observation of microstructure, potentio dynamic test, SEM-EDS analysis, and X-ray diffraction analysis. As the aging time increased, the fraction of δ-ferrite decreased sharply, but the fraction of γ slightly increased. The σ phase was generated at a non-metallic inclusion along the grain boundaries of δ-ferrite and γ, while the χ phase was generated in the structure of δ-ferrite. As the intermetallic compounds increased, the critical pitting potential fell sharply, and PREN of the surrounding structure decreased by 5 due to precipitation of the σ phase in 3.5% NaCl at 60 ℃. Pitting occurred intensively under a multi-pass line which relatively had more intermetallic compounds, and the precipitation of the σ phase caused the formation of Cr carbide.

On an inner product over Imc *-algebras

International Nuclear Information System (INIS)

Mohammad, N.; Verjovsky, A.

1991-08-01

An inner product is defined on a commutative *-semisimple separable Frechet Q Imc *-algebra A and the resultant space A m is shown to be a topological *-algebra. It is also proved that every maximal ideal M of A is A m -closed and thus A can be decomposed into A = M + M perpendicular . Further, it is shown that a norm can be defined on A which makes it into a pre C * -algebra. A completeness criterion for A m is established. (author). 10 refs

The effect of pH on the corrosion behavior of intermetallic compounds Ni{sub 3}(Si,Ti) and Ni{sub 3}(Si,Ti) + 2Mo in sodium chloride solutions

Energy Technology Data Exchange (ETDEWEB)

Priyotomo, Gadang, E-mail: gada001@lipi.go.id; Nuraini, Lutviasari, E-mail: Lutviasari@gmail.com [Research Center for Metallurgy and Material, Indonesian Institute of Sciences, Kawasan PUSPIPTEK Gd.474, Setu, Tangerang Selatan, Banten 15314 (Indonesia); Kaneno, Yasuyuki, E-mail: kaneno@mtr.osakafu-u.ac.id [Department of Materials Science, Graduate School of Engineering, Osaka Prefecture University, 1-1 Gakuen-cho, Sakai, Osaka 599-8531 (Japan)

2015-12-29

The corrosion behavior of the intermetallic compounds, Ni{sub 3}(Si,Ti) (L1{sub 2}: single phase) and Ni{sub 3}(Si,Ti) + 2Mo (L1{sub 2} and (L12 + Ni{sub ss}) mixture region), has been investigated using an immersion test, electrochemical method and surface analytical method (SEM; scanning electron microscope and EDAX: Energy Dispersive X-ray) in 0.5 kmol/m{sup 3} NaCl solutions at various pH. The corrosion behavior of nickel alloy C-276 was studied under the same experimental conditions as a reference. It was found that the uniform attack was observed on Ni{sub 3}(Si,Ti) for the immersion test at lower pH, while the pitting attack was observed on this compound for this test at neutral solution. Furthermore, Ni{sub 3}(Si,Ti)+2Mo had the preferential dissolution of L1{sub 2} compared to (L1{sub 2} + Ni{sub ss}) mixture region at lower pH, while pitting attack occurred in (L1{sub 2} + Ni{sub ss}) mixture region at neutral solution. For both intermetallic compounds, the magnitude of pitting and uniform attack decrease with increasing pH of solutions. From the immersion test and polarization curves, the corrosion resistance of Ni{sub 3}(Si,Ti)+2Mo is lower than that of Ni{sub 3}(Si,Ti), while the nickel alloy C-276 is the highest one at various pH of solutions. On the other hand, in the lower pH of solutions, the corrosion resistance of tested materials decreased significantly compared to those in neutral and higher pH of solutions.

Microstructural analyses of intermetallic TiAl(Nb)-compounds prepared by arc melting and by powder metallurgy

International Nuclear Information System (INIS)

Chen, S.

1988-01-01

Intermetallic compounds based on TiAl with Nb or V as alloying additions prepared by powder metallurgy (P/M) and arc melting (A/M) techniques have been investigated with respect to their potential as new high temperature materials. All the alloys with nominal Al-concentrations 34-36 wt% contain two phases, γ-TiAl and α 2 -Ti 3 Al, but significant differences in the distribution of γ and α 2 were found between the P/M and A/M materials. The role of impurities during processing and the microstructural stability in the planned service temperature range 700-1000 0 C are discussed. In the P/M TiAl alloys two carbide precipitates have been found, which are the cubic Perovskite-AlTi 3 C phase in the γ-matrix and the hexagonal H-AlTi 2 (C, N) phase at grain boundaries. At high temperatures the AlTi 3 C phase dissolves and is replaced by more stable H-phase, and therefore no longer contributes to the high temperature strength of the material. Mechanical properties of both the P/M and A/M alloys are compared in association with the processing methods and the resulting microstructures. (orig.) With 71 figs., 22 tabs [de

Multifunctional phenomena in rare-earth intermetallic compounds with a laves phase structure: giant magnetostriction and magnetocaloric effect

Czech Academy of Sciences Publication Activity Database

Tereshina, I.; Cwik, J.; Tereshina, Evgeniya; Politova, G.; Burkhanov, G.; Chzhan, V.; Ilyushin, A.; Miller, M.; Zaleski, A.; Nenkov, K.; Schultz, L.

2014-01-01

Roč. 50, č. 11 (2014), s. 2504604 ISSN 0018-9464 Institutional support: RVO:68378271 Keywords : giant magnetostriction * Laves phase structure * magnetic anisotropy * magnetocaloric effect * rare-earth intermetallic Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.386, year: 2014

Fully in Silico Calibration of Empirical Predictive Models for Environmental Fate Properties of Novel Munitions Compounds

Science.gov (United States)

2016-04-01

constants using several IMC related aromatic amines. To develop QSARs with these data, many possible descriptors were evaluated , ranging from simple to...converted to approximate half-lives to give. The blue symbols are experimental data, obtained with IMC related amino compounds...calibrated “in silico” that predict the hydrolysis behavior of the diverse range of energetic NACs. However, new experimental and computational

The Shear Strength and Fracture Behavior of Sn-Ag- xSb Solder Joints with Au/Ni-P/Cu UBM

Science.gov (United States)

Lee, Hwa-Teng; Hu, Shuen-Yuan; Hong, Ting-Fu; Chen, Yin-Fa

2008-06-01

This study investigates the effects of Sb addition on the shear strength and fracture behavior of Sn-Ag-based solders with Au/Ni-P/Cu underbump metallization (UBM) substrates. Sn-3Ag- xSb ternary alloy solder joints were prepared by adding 0 wt.% to 10 wt.% Sb to a Sn-3.5Ag alloy and joining them with Au/Ni-P/Cu UBM substrates. The solder joints were isothermally stored at 150°C for up to 625 h to study their microstructure and interfacial reaction with the UBM. Single-lap shear tests were conducted to evaluate the mechanical properties, thermal resistance, and failure behavior. The results show that UBM effectively suppressed intermetallic compound (IMC) formation and growth during isothermal storage. The Sb addition helped to refine the Ag3Sn compounds, further improving the shear strength and thermal resistance of the solders. The fracture behavior evolved from solder mode toward the mixed mode and finally to the IMC mode with increasing added Sb and isothermal storage time. However, SnSb compounds were found in the solder with 10 wt.% Sb; they may cause mechanical degradation of the solder after long-term isothermal storage.

Method of production multifilamentary intermetallic superconductors

International Nuclear Information System (INIS)

Marancik, W.G.; Young, M.S.

1980-01-01

A method of making A-15 type intermetallic superconductors is disclosed which features elimination of numerous annealing steps. Nb or V filaments are embedded in Cu matrices; annular layers of Sn or Ga, respectively, separated from each other by Cu layers, provide the other component of the intermetallic superconductors Nb3Sn and V3Ga

Evaluation of Die-Attach Bonding Using High-Frequency Ultrasonic Energy for High-Temperature Application

Science.gov (United States)

Lee, Jong-Bum; Aw, Jie-Li; Rhee, Min-Woo

2014-09-01

Room-temperature die-attach bonding using ultrasonic energy was evaluated on Cu/In and Cu/Sn-3Ag metal stacks. The In and Sn-3Ag layers have much lower melting temperatures than the base material (Cu) and can be melted through the heat generated during ultrasonic bonding, forming intermetallic compounds (IMCs). Samples were bonded using different ultrasonic powers, bonding times, and forces and subsequently aged at 300°C for 500 h. After aging, die shear testing was performed and the fracture surfaces were inspected by scanning electron microscopy. Results showed that the shear strength of Cu/In joints reached an upper plateau after 100 h of thermal aging and remained stable with aging time, whereas that of the Cu/Sn-3Ag joints decreased with increasing aging time. η-Cu7In4 and (Cu,Au)11In9 IMCs were observed at the Cu/In joint, while Cu3Sn and (Ag,Cu)3Sn IMCs were found at the Cu/Sn-3Ag joint after reliability testing. As Cu-based IMCs have high melting temperatures, they are highly suitable for use in high-temperature electronics, but can be formed at room temperature using an ultrasonic approach.

Microstructure and Tensile Behavior of Laser Arc Hybrid Welded Dissimilar Al and Ti Alloys

Directory of Open Access Journals (Sweden)

Ming Gao

2014-02-01

Full Text Available Fiber laser-cold metal transfer arc hybrid welding was developed to welding-braze dissimilar Al and Ti alloys in butt configuration. Microstructure, interface properties, tensile behavior, and their relationships were investigated in detail. The results show the cross-weld tensile strength of the joints is up to 213 MPa, 95.5% of same Al weld. The optimal range of heat input for accepted joints was obtained as 83–98 J·mm−1. Within this range, the joint is stronger than 200 MPa and fractures in weld metal, or else, it becomes weaker and fractures at the intermetallic compounds (IMCs layer. The IMCs layer of an accepted joint is usually thin and continuous, which is about 1μm-thick and only consists of TiAl2 due to fast solidification rate. However, the IMCs layer at the top corner of fusion zone/Ti substrate is easily thickened with increasing heat input. This thickened IMCs layer consists of a wide TiAl3 layer close to FZ and a thin TiAl2 layer close to Ti substrate. Furthermore, both bead shape formation and interface growth were discussed by laser-arc interaction and melt flow. Tensile behavior was summarized by interface properties.

Structural and functional intermetallics - an overview

International Nuclear Information System (INIS)

Varin, R.A.

2000-01-01

This overview presents the current status of the research and development of both structural and functional intermetallics. On the one hand, the discussion is focused on commercialization and existing industrial applications of intermetallics. Within this frame the applications of titanium aluminides (TiAl) for turbocharger rotors and exhaust valves in automotive industry are being discussed. Advances in the applications of TiAl alloys for the next generation of turbine blades in aerospace/aircraft segment are also presented. The entire spectrum of nickel and iron aluminide alloys developed commercially by the Oak Ridge national Laboratory (USA) and the examples of their application in various segments of industry are thoroughly discussed. Some inroads made in the application of directionally solidified (DS) multiphase niobium silicides (Nb 3 Si+Nb 5 Si 3 ) in situ intermetallic composites with the goal of pushing the service temperature envelope of turbine blades to ∼ 1200-1300 o C are also discussed. On the other hand, various topics in basic or curiosity driven research of titanium aluminides and trialuminides, iron aluminides and high temperature structural silicides are discussed. Some very recent findings on the improvements in fracture toughness and strength of titanium trialuminides and magnetic behaviour of unconventionally cold - worked iron aluminides are highlighted. The topic of functional intermetallics is limited to the systems must suitable for hydrogen storage applications. A perspective on the directions of future research and development of intermetallics is also provided. (author)

The Impact of IMC on Advertising and Public Relations Education.

Science.gov (United States)

Griffin, W. Glenn; Pasadeos, Yorgo

1998-01-01

Surveys advertising and public relations faculty members with regard to IMC (Integrated Marketing Communications) and its impact on current curricula. Finds (1) areas of discontent with current course curricula; (2) evidence of "separate agendas" between advertising and public relations educators on this issue; and (3) evidence of a generation gap…

Preparation of Fe-Al Intermetallic / TiC-Al2O3 Ceramic Composites from Ilmenite by SHS

Institute of Scientific and Technical Information of China (English)

无

2007-01-01

Fe-Al intermetallic/TiC-Al2O3 ceramic composites were successfully prepared by self-propagating high-temperature synthesis (SHS) from natural ilmenite, aluminium and carbon as the raw materials. The effects of carbon sources, preheating time and heat treatment temperature on synthesis process and products were investigated in detail, and the reaction process of the FeTiO3-Al-C system was also discussed.It is shown that the temperature and velocity of the combustion wave are higher when graphite is used as the carbon source, which can reflect the effect of the carbon source structure on the combustion synthesis;Prolonging the preheating time or heat treatment temperature is beneficial to the formation of the ordered intermetallics; The temperature and velocity of the combustion wave arc improved, but the disordered alloys are difficult to eliminate with the preheating time prolonged. The compound powders mainly containing ordered Fe3Al intermetallic can be prepared through heat treatment at 750 ℃.

Self-propagating high-temperature synthesis flammable range and dominant parameters for synthesizing several ceramics and intermetallic compounds under heat-loss condition

International Nuclear Information System (INIS)

Makino, Atsushi

1996-01-01

Extensive comparisons have been conducted between experimental and theoretical results for the nonadiabatic self-propagating high-temperature synthesis combustion characteristics of many solid-solid systems subjected to volumetric heat loss. The nonadiabatic flame propagation theory--which describes the premixed mode of bulk flame propagation supported by the nonpremixed reaction of dispersed nonmetal (or higher-melting point metal) particles in the liquid metal, with finite-rate reaction at the particle surface and temperature-sensitive Arrhenius-type condensed-phase mass diffusivity--is used to compare with experimental results with heat loss. Systems examined are ceramics (TiC, TiB 2 , and ZrB 2 ) and intermetallic compounds (NiAl, TiCo, and TiNi). By using a consistent set of physicochemical parameters for these systems, satisfactory quantitative agreement is demonstrated for the flammable range (defined in terms of the mixture ratio, degree of dilution, particle size, and/or compact diameter)

Zirconium intermetallics and hydrogen uptake during corrosion

International Nuclear Information System (INIS)

Cox, B.

1987-04-01

The routes by which hydrogen can enter zirconium alloys containing second phase particles during corrosion are discussed. Both direct diffusion through the bulk of the oxide film, and migration through second phase particles that intersect the surface are considered. An examination of results for hydrogen uptake by zirconium alloys during the early stages of oxidation, when the oxide film is still coherent, suggests that for Zr, Zr-1%Cu and Zr-1%Fe the hydrogen enters by diffusing through the bulk ZrO 2 film, whereas for the Zircaloys the primary migration route may be through the intermetallics. The steps in the latter process are discussed and the evidence available on the properties of the intermetallics collated. A comparison of these data with results for hydrogen uptake by two series of ternary alloys (Zr-1%Nb - 1%X, Zr-1%Cu - 1%X) suggests that high hydrogen uptakes often correlate with intermetallics with high hydrogen solubilities and vice versa. The properties of Zr(Fe/Cr) 2+x intermetallics are examined in an attempt to understand the behaviour of the Zircaloys, and it is concluded that present data establishing composition and unit cell dimensions for such intermetallic particles are not of sufficient accuracy to permit a correlation

Persistent local chemical bonds in intermetallic phase formation

Energy Technology Data Exchange (ETDEWEB)

Bai, Yanwen [Key Laboratory for Liquid–Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Jinan 250061 (China); Bian, Xiufang, E-mail: xfbian@sdu.edu.cn [Key Laboratory for Liquid–Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Jinan 250061 (China); Qin, Xubo [Key Laboratory for Liquid–Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Jinan 250061 (China); Zhang, Shuo; Huang, Yuying [Shanghai Synchrotron Radiation Facilities, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201204 (China)

2014-05-01

We found a direct evidence for the existence of the local chemical Bi–In bonds in the BiIn{sub 2} melt. These bonds are strong and prevail, dominating the structure evolution of the intermetallic clusters. From the local structure of the melt-quenched BiIn{sub 2} ribbon, the chemical Bi–In bonds strengthen compared with those in the equilibrium solidified alloy. The chemical bonds in BiIn{sub 2} melt retain to solid during a rapid quenching process. The results suggest that the intermetallic clusters in the melt evolve into the as-quenched intermetallic phase, and the intermetallic phase originates from the chemical bonds between unlike atoms in the melt. The chemical bonds preserve the chemical ordered clusters and dominate the clusters evolution.

Negative thermal expansion induced by intermetallic charge transfer.

Science.gov (United States)

Azuma, Masaki; Oka, Kengo; Nabetani, Koichiro

2015-06-01

Suppression of thermal expansion is of great importance for industry. Negative thermal expansion (NTE) materials which shrink on heating and expand on cooling are therefore attracting keen attention. Here we provide a brief overview of NTE induced by intermetallic charge transfer in A-site ordered double perovskites SaCu 3 Fe 4 O 12 and LaCu 3 Fe 4- x Mn x O 12 , as well as in Bi or Ni substituted BiNiO 3 . The last compound shows a colossal dilatometric linear thermal expansion coefficient exceeding -70 × 10 -6 K -1 near room temperature, in the temperature range which can be controlled by substitution.

Limitation of critical current density by intermetallic formation in fine filament Nb-Ti superconductors

International Nuclear Information System (INIS)

Larbalestier, D.C.; Chengren, L.; Starch, W.; Lee, P.J.

1985-01-01

Two experiments have been performed to investigate the role that the intermetallic reaction between the copper matrix and the Nb-Ti filaments plays in limiting the critical current density (J/sub c/) of Nb 45.6 wt% Ti composites. The first experiment involved composites which were industrially extruded. It was found that as the number of heat treatments increased, the J/sub c/ declined, the resistive transition broadened and the filaments sausaged. The filament sausaging was initiated by intermetallic particles at the filament matrix interface. A series of many heat treatment procedures were then applied to composites fabricated in the authors own laboratories without extrusion. Very high J/sub c/ values were obtained at filament sizes of 20 μm. When the same heat treatment procedures were applied to 4 - 5 μm conductors, extensive sausaging and degraded J/sub c/ values resulted. This degradation was also found to be due to the formation of Cu-Nb-Ti intermetallic compounds. It is concluded that a reliable filament diffusion barrier technology is necessary to permit full flexibility in the heat treatment of 2 - 5 μ filament Nb-Ti composites

Limitation of critical current density by intermetallic formation in fine filament Nb-Ti superconductors

International Nuclear Information System (INIS)

Larbalestier, D.C.; Chengren, Li; Lee, P.J.; Starch, W.

1985-01-01

Two experiments have been performed to investigate the role that the intermetallic reaction between the copper matrix and the Nb-Ti filaments plays in limiting the critical current density (J /SUB c/ ) of Nb 46.5 wt% Ti composites. The first experiment involved composites which were industrially extruded. It was found that as the number of heat treatments increased, the J /SUB c/ declined, the resistive transition broadened and the filaments sausaged. The filament sausaging was initiated by intermetallic particles at the filament matrix interface. A series of many heat treatment procedures were then applied to composites fabricated in our own laboratories without extrusion. Very high J /SUB c/ values were obtained at filament sizes of 20 μm. When the same heat treatment procedures were applied to 4 - 5 μm conductors, extensive sausaging and degraded J /SUB c/ values resulted. This degradation was also found to be due to the formation of Cu-Nb-Ti intermetallic compounds. It is concluded that a reliable filament diffusion barrier technology is necessary to permit full flexibility in the heat treatment of 2 - 5 μm filament Nb-Ti composites

Post-heat treatment of arc-sprayed coating prepared by the wires combination of Mg-cathode and Al-anode to form protective intermetallic layers

International Nuclear Information System (INIS)

Xu Rongzheng; Song Gang

2011-01-01

A Mg-Al intermetallic compounds coating was prepared on the surface of Mg-steel lap joint by arc-sprayed Al-Mg composite coating (Mg-cathode and Al-anode) and its post-heat treatment (PHT). The effect of PHT temperature on the phase transition, microstructure and mechanical properties of the coating was investigated by X-ray diffraction, scanning electron microscope, energy dispersive X-ray spectroscopy, optical microscope and microhardness test. The result shows that the intermetallic compounds layer that is mainly composed of Al 3 Mg 2 and Mg 17 Al 12 is formed by the self-diffusion reaction of Mg and Al splats in the coating after PHT for 4 h at 430 deg. C.

Intermetallic alloys: Deformation, mechanical and fracture behaviour

International Nuclear Information System (INIS)

Dogan, B.

1988-01-01

The state of the art in intermetallic alloys development with particular emphasis on deformation, mechanical and fracture behaviour is documented. This review paper is prepared to lay the ground stones for a future work on mechanical property characterization and fracture behaviour of intermetallic alloys at GKSS. (orig.)

Enthalpies of formation of Cd0.917Sr0.083, Cd0.857Sr0.143 and Cd0.667Sr0.333 intermetallic compounds

International Nuclear Information System (INIS)

Agarwal, Renu; Singh, Ziley

2008-01-01

Cadmium is expected to be the solvent for pyrochemical processing of the metallic nuclear fuel. Therefore, thermodynamic properties of cadmium with various fuel and clad elements are of interest. Enthalpies of formation of the intermetallic compounds of Cd-Sr system, Cd 0.917 Sr 0.083 , Cd 0.857 Sr 0.143 and Cd 0.667 Sr 0.333 were determined by precipitation using Calvet calorimeter. Enthalpies of formation of the compounds were found to be -3.05 ± 0.5 kJ mol -1 at 723 K, -14.2 ± 0.7 kJ mol -1 at 843 K and -28.4 ± 0.8 kJ mol -1 at 863 K, respectively. Enthalpies of formation of Cd 0.917 Sr 0.083 and Cd 0.857 Sr 0.143 were also determined by partial enthalpy of formation measurements and the values were found to be -3.9 ± 1.1 kJ mol -1 at 723 K and -13.42 ± 1.2 kJ mol -1 at 843 K, respectively. Miedema model was used to estimate the enthalpies of formation of these compounds and the estimated values were compared with the experimentally determined values

Lattice anisotropy in uranium ternary compounds

DEFF Research Database (Denmark)

Maskova, S.; Adamska, A.M.; Havela, L.

2012-01-01

Several U-based intermetallic compounds (UCoGe, UNiGe with the TiNiSi structure type and UNiAl with the ZrNiAl structure type) and their hydrides were studied from the point of view of compressibility and thermal expansion. Confronted with existing data for the compounds with the ZrNiAl structure...

Investigations of intermetallic alloy hydriding mechanisms. Annual progress report, May 1 1979-April 30, 1980

International Nuclear Information System (INIS)

Livesay, B.R.; Larsen, J.W.

1980-05-01

Investigations are being conducted on mechanisms involved with the hydrogen-metal interactions which control the absorption and desorption processes in intermetallic compounds. The status of the following investigations is reported: modeling of hydride formation; microbalance investigations; microstructure investigations; flexure experiments; resistivity experiments; and nuclear backscattering measurements. These investigations concern fundamental hydrogen interaction mechanisms involved in storage alloys

The μ3 model of acids and bases: extending the Lewis theory to intermetallics.

Science.gov (United States)

Stacey, Timothy E; Fredrickson, Daniel C

2012-04-02

A central challenge in the design of new metallic materials is the elucidation of the chemical factors underlying the structures of intermetallic compounds. Analogies to molecular bonding phenomena, such as the Zintl concept, have proven very productive in approaching this goal. In this Article, we extend a foundational concept of molecular chemistry to intermetallics: the Lewis theory of acids and bases. The connection is developed through the method of moments, as applied to DFT-calibrated Hückel calculations. We begin by illustrating that the third and fourth moments (μ(3) and μ(4)) of the electronic density of states (DOS) distribution tune the properties of a pseudogap. μ(3) controls the balance of states above and below the DOS minimum, with μ(4) then determining the minimum's depth. In this way, μ(3) predicts an ideal occupancy for the DOS distribution. The μ(3)-ideal electron count is used to forge a link between the reactivity of transition metals toward intermetallic phase formation, and that of Lewis acids and bases toward adduct formation. This is accomplished through a moments-based definition of acidity which classifies systems that are electron-poor relative to the μ(3)-ideal as μ(3)-acidic, and those that are electron-rich as μ(3)-basic. The reaction of μ(3) acids and bases, whether in the formation of a Lewis acid/base adduct or an intermetallic phase, tends to neutralize the μ(3) acidity or basicity of the reactants. This μ(3)-neutralization is traced to the influence of electronegativity differences at heteroatomic contacts on the projected DOS curves of the atoms involved. The role of μ(3)-acid/base interactions in intermetallic phases is demonstrated through the examination of 23 binary phases forming between 3d metals, the stability range of the CsCl type, and structural trends within the Ti-Ni system.

Microstructure and mechanical properties of friction stir lap welded Mg/Al joint assisted by stationary shoulder

Science.gov (United States)

Ji, Shude; Li, Zhengwei

2017-11-01

Using magnesium alloy as upper sheet, 3 mm-thick AZ31 magnesium alloy and 6061 aluminum alloy were joined using friction stir lap welding assisted by stationary shoulder. The effects of tool rotating speed on cross-sections, microstructure and mechanical properties of Mg/Al lap joints were mainly discussed. Results showed that stationary shoulder contributed to joint formation, by which stir zones (SZ) were characterized by big onion rings after welding. Because of the big forging force exerted by stationary shoulder, the upper region of hook was well bonded. SZ showed much higher hardness because of intermetallic compounds (IMCs). The bonding conditions at the base material (BM)/SZ interface at advancing side and the hook region played important roles on joint lap shear properties. The X-ray diffraction pattern analysis revealed that the main IMCs were Al3Mg2 and Al12Mg17.

Coordinating IMC-PID and adaptive SMC controllers for a PEMFC.

Science.gov (United States)

Wang, Guo-Liang; Wang, Yong; Shi, Jun-Hai; Shao, Hui-He

2010-01-01

For a Proton Exchange Membrane Fuel Cell (PEMFC) power plant with a methanol reformer, the process parameters and power output are considered simultaneously to avoid violation of the constraints and to keep the fuel cell power plant safe and effective. In this paper, a novel coordinating scheme is proposed by combining an Internal Model Control (IMC) based PID Control and adaptive Sliding Mode Control (SMC). The IMC-PID controller is designed for the reformer of the fuel flow rate according to the expected first-order dynamic properties. The adaptive SMC controller of the fuel cell current has been designed using the constant plus proportional rate reaching law. The parameters of the SMC controller are adaptively tuned according to the response of the fuel flow rate control system. When the power output controller feeds back the current references to these two controllers, the coordinating controllers system works in a system-wide way. The simulation results of the PEMFC power plant demonstrate the effectiveness of the proposed method. 2009 ISA. Published by Elsevier Ltd. All rights reserved.

Development of a double beam process for joining aluminum and steel

Science.gov (United States)

Frank, Sascha

2014-02-01

Multi-material structures pose an attractive option for overcoming some of the central challenges in lightweight design. An exceptionally high potential for creating cost-effective lightweight solutions is attributed to the combination of steel and aluminum. However, these materials are also particularly difficult to join due to their tendency to form intermetallic compounds (IMCs). The growth of these compounds is facilitated by high temperatures and long process times. Due to their high brittleness, IMCs can severely weaken a joint. Thus, it is only possible to create durable steel-aluminum joints when the formation of IMCs can be limited to a non-critical level. To meet this goal, a new joining method has been designed. The method is based on the combination of a continuous wave (pw) and a pulsed laser (pw) source. Laser beams from both sources are superimposed in a common process zone. This makes it possible to apply the advantages of laser brazing to mixed-metal joints without requiring the use of chemical fluxes. The double beam technology was first tested in bead-on-plate experiments using different filler wire materials. Based on the results of these tests, a process for joining steel and aluminum in a double-flanged configuration is now being developed. The double flanged seams are joined using zinc- or aluminum-based filler wires. Microsections of selected seams show that it is possible to achieve good base material wetting while limiting the growth of IMCs to acceptable measures. In addition, the results of tensile tests show that high joint strengths can be achieved.

Interface analysis of embedded chip resistor device package and its effect on drop shock reliability.

Science.gov (United States)

Park, Se-Hoon; Kim, Sun Kyoung; Kim, Young-Ho

2012-04-01

In this study, the drop reliability of an embedded passive package is investigated under JESD22-B111 condition. Chip resistors were buried in a PCB board, and it was electrically interconnected by electroless and electrolytic copper plating on a tin pad of a chip resistor without intermetallic phase. However tin, nickel, and copper formed a complex intermetallic phase, such as (Cu, Ni)6Sn5, (Cu, Ni)3Sn, and (Ni, Cu)3Sn2, at the via interface and via wall after reflow and aging. Since the amount of the tin layer was small compared with the solder joint, excessive intermetallic layer growth was not observed during thermal aging. Drop failures are always initiated at the IMC interface, and as aging time increases Cu-Sn-Ni IMC phases are transformed continuously due to Cu diffusion. We studied the intermetallic formation of the Cu via interface and simulated the stress distribution of drop shock by using material properties and board structure of embedded passive boards. The drop simulation was conducted according to the JEDEC standard. It was revealed that the crack starting point related to failure fracture changed due to intermetallic phase transformation along the via interface, and the position where failure occurs experimentally agrees well with our simulation results.

Size effects in tin-based lead-free solder joints: Kinetics of bond formation and mechanical characteristics

Science.gov (United States)

Abdelhadi, Ousama Mohamed Omer

Continuous miniaturization of microelectronic interconnects demands smaller joints with comparable microstructural and structural sizes. As the size of joints become smaller, the volume of intermetallics (IMCs) becomes comparable with the joint size. As a result, the kinetics of bond formation changes and the types and thicknesses of IMC phases that form within the constrained region of the bond varies. This dissertation focuses on investigating combination effects of process parameters and size on kinetics of bond formation, resulting microstructure and the mechanical properties of joints that are formed under structurally constrained conditions. An experiment is designed where several process parameters such as time of bonding, temperature, and pressure, and bond thickness as structural chracteristic, are varied at multiple levels. The experiment is then implemented on the process. Scanning electron microscope (SEM) is then utilized to determine the bond thickness, IMC phases and their thicknesses, and morphology of the bonds. Electron backscatter diffraction (EBSD) is used to determine the grain size in different regions, including the bulk solder, and different IMC phases. Physics-based analytical models have been developed for growth kinetics of IMC compounds and are verified using the experimental results. Nanoindentation is used to determine the mechanical behavior of IMC phases in joints in different scales. Four-point bending notched multilayer specimen and four-point bending technique were used to determine fracture toughness of the bonds containing IMCs. Analytical modeling of peeling and shear stresses and fracture toughness in tri-layer four-point bend specimen containing intermetallic layer was developed and was verified and validated using finite element simulation and experimental results. The experiment is used in conjunction with the model to calculate and verify the fracture toughness of Cu6Sn5 IMC materials. As expected two different IMC phases

The variation of grain structure and the enhancement of shear strength in SAC305-0.1Ni/OSP Cu solder joint

Energy Technology Data Exchange (ETDEWEB)

Fleshman, Collin; Chen, Wei-Yu; Chou, Tzu-Ting [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu, Taiwan (China); Huang, Jia-Hong [Department of Engineering and System Science, National Tsing Hua University, Hsinchu, Taiwan (China); Duh, Jenq-Gong, E-mail: jgd@mx.nthu.edu.tw [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu, Taiwan (China)

2017-03-01

In this study, the slow speed shear test in both Sn-3.0Ag-0.5Cu (wt%)/OSP Cu and Sn-3.0Ag-0.5Cu-0.1Ni (wt%)/OSP Cu assembly with the ball heights of 300 μm and the corresponding grain structures were investigated. With the aid of Electron Back Scattering Diffraction (EBSD) analysis, single grain structure was observed in Sn-3.0Ag-0.5Cu/OSP Cu. Besides, Ni was found to control the grain structure in Sn-3.0Ag-0.5Cu-0.1Ni solder balls, showing multiple grains with partially interlaced structure. The grain variation resulted from larger undercooling caused by smaller ball size and Ni-dopant induced tiny intermetallic compounds (IMCs). IMCs serve as heterogeneous nucleation sites for β-tin and thus alter the grain structure of solder balls. The results of shear test reveal that the peak force of solder joints was efficiently enhanced by the addition of Ni. The enhancement of mechanical strength was attributed to the modification of grain structure by the introduction of Ni dopant. It is believed that the smaller grains, tiny intermetallic compounds, and the oriented interlaced area in Ni-doped solder joints became energy barriers for propagation of cracks and dislocations. It is demonstrated that Ni-doped solder joints tend to exhibit better mechanical reliability in advanced electronic packaging. - Highlights: • The grain structure and slow speed shear test performance were investigated. • Doping Ni into solder induce interlaced grain structure. • Interlaced structure can enhance mechanical reliability in BGA packaging.

Magnetic and superconducting order in some random pseudobinary compounds

International Nuclear Information System (INIS)

Dongen, J.C.M. van.

1982-01-01

This thesis presents the results of a study on the magnetic and superconducting ordering phenomena in some random pseudobinary compounds. In the investigations ternary systems are utilised in which two of the elements form a binary intermetallic compound, e.g. PdH, GdCu and YCo 2 . A third element is then randomly substituted into one of the sublattices without changing the basic intermetallic compound structure. In chapter II a study is presented on the Kondo effect and spin-glass freezing of the magnetic impurities Cr, Mn, and Fe in superconducting palladium hydride. Chapter III contains a study on crystal structure transformations and magnetic ordering phenomena in GdCusub(1-x)Gasub(x) and related pseudobinary compounds. In Chapter IV experiments on the magnetic properties and the electrical resistivity of the transition metal Laves phase compounds Y(Cosub(1-x)Fesub(x)) 2 , Y(Irsub(1-x)Fesub(x)) 2 and Hf(Cosub(1-x)Fesub(x)) 2 are described. (Auth.)

A Comparative Discussion of the Catalytic Activity and CO2-Selectivity of Cu-Zr and Pd-Zr (Intermetallic Compounds in Methanol Steam Reforming

Directory of Open Access Journals (Sweden)

Norbert Köpfle

2017-02-01

Full Text Available The activation and catalytic performance of two representative Zr-containing intermetallic systems, namely Cu-Zr and Pd-Zr, have been comparatively studied operando using methanol steam reforming (MSR as test reaction. Using an inverse surface science and bulk model catalyst approach, we monitored the transition of the initial metal/intermetallic compound structures into the eventual active and CO2-selective states upon contact to the methanol steam reforming mixture. For Cu-Zr, selected nominal stoichiometries ranging from Cu:Zr = 9:2 over 2:1 to 1:2 have been prepared by mixing the respective amounts of metallic Cu and Zr to yield different Cu-Zr bulk phases as initial catalyst structures. In addition, the methanol steam reforming performance of two Pd-Zr systems, that is, a bulk system with a nominal Pd:Zr = 2:1 stoichiometry and an inverse model system consisting of CVD-grown ZrOxHy layers on a polycrystalline Pd foil, has been comparatively assessed. While the CO2-selectivity and the overall catalytic performance of the Cu-Zr system is promising due to operando formation of a catalytically beneficial Cu-ZrO2 interface, the case for Pd-Zr is different. For both Pd-Zr systems, the low-temperature coking tendency, the high water-activation temperature and the CO2-selectivity spoiling inverse WGS reaction limit the use of the Pd-Zr systems for selective MSR applications, although alloying of Pd with Zr opens water activation channels to increase the CO2 selectivity.

Predicting the stability of ternary intermetallics with density functional theory and machine learning

Science.gov (United States)

Schmidt, Jonathan; Chen, Liming; Botti, Silvana; Marques, Miguel A. L.

2018-06-01

We use a combination of machine learning techniques and high-throughput density-functional theory calculations to explore ternary compounds with the AB2C2 composition. We chose the two most common intermetallic prototypes for this composition, namely, the tI10-CeAl2Ga2 and the tP10-FeMo2B2 structures. Our results suggest that there may be ˜10 times more stable compounds in these phases than previously known. These are mostly metallic and non-magnetic. While the use of machine learning reduces the overall calculation cost by around 75%, some limitations of its predictive power still exist, in particular, for compounds involving the second-row of the periodic table or magnetic elements.

Mechanical properties of aluminium matrix composites reinforced with intermetallics

International Nuclear Information System (INIS)

Torres, B.; Garcia-Escorial, A.; Ibanez, J.; Lieblich, M.

2001-01-01

In this work 2124 aluminium matrix composites reinforced with Ni 3 Al, NiAl, MoSi 2 and Cr 3 Si intermetallic powder particles have been investigated. For comparison purposes, un reinforced 2124 and reinforced with SiC have also been studied. In all cases, the same powder metallurgy route was used, i. e. the 2124 alloy was obtained by rapid solidification and the intermetallic particles by self-propagating high-temperature synthesis (SHS). The matrix and the intermetallics were mechanically blended, cold compacted and finally hot extruded. Tensile tests were carried out in T1 and T4 treatments. Results indicate that mechanical properties depend strongly on the tendency to form new phases at the matrix-intermetallic interface during processing and/or further thermal treatments. The materials which present better properties are those that present less reaction between matrix and intermetallic reinforcement, i. e. MoSi 2 and SiC reinforced composites. (Author) 9 refs

Investigation of AA2024-T3 surfaces modified by cerium compounds: A localized approach

International Nuclear Information System (INIS)

Paussa, L.; Andreatta, F.; De Felicis, D.; Bemporad, E.; Fedrizzi, L.

2014-01-01

Highlights: •The precipitation of cerium compounds occurs on the entire AA2024-T3 surface. •The matrix is less involved in the cerium precipitation. •Cerium intensely precipitates on Mg-rich IM particles. •The electrochemical behavior of Mg-rich IM particles influences the mechanism of cerium precipitation. -- Abstract: The precipitation of cerium compounds on polished AA2024-T3 surfaces was investigated following an electrochemical and microstructural localized approach. It was found that cerium precipitation occurs on the entire surface covering intermetallic particles and the matrix as well. The matrix is the region where the precipitation of cerium is less favoured. The highest amount of cerium was observed on magnesium-rich intermetallic particles. The localized analyses suggest that precipitation of cerium on magnesium-rich intermetallic particles could happen following two mechanisms: the former based on a potential reversal of the intermetallic particles and the latter due to a partial magnesium dissolution

Intensive structural investigation of R{sub 2}Fe{sub 17-x}M{sub x} intermetallic compounds using high resolution powder neutron diffractometer

Energy Technology Data Exchange (ETDEWEB)

Mujamilah,; Ridwan, [Materials Science Research Center, National Atomic Energy Agency of Indonesia, Jakarta (Indonesia)

1998-10-01

The crystallographic and magnetic structure of R{sub 2}Fe{sub 17-x}M{sub x} intermetallic compounds system were refined by Rietveld analyses of the high resolution neutron powder diffraction data. The analyses results show that the substituent atoms were not distributed randomly over the Fe sites, but preferentially occupied some Fe sites. More further, it was also found that the substituent atoms which atomic radius smaller than Fe tend to avoid the 6c site at low concentration while the larger substituent atom tend to replace the Fe atom at this 6c site corresponding to their concentration. From these crystallographic data, it was suggested that the change of magnetic ordering temperature Tc, is not mainly determined by the change of short bond distance between this `dumb-bell` atoms, but it was also influenced by the nearest coordinated atoms to this site. (author)

Synthesis, Characterization and Properties of Nanoparticles of Intermetallic Compounds

Energy Technology Data Exchange (ETDEWEB)

DiSalvo, Francis J. [Cornell Univ., Ithaca, NY (United States)

2015-03-12

The research program from 2010 to the end of the grant focused on understanding the factors important to the synthesis of single phase intermetallic nano-particles (NPs), their size, crystalline order, surface properties and electrochemical activity. The synthetic method developed is a co-reduction of mixtures of single metal precursors by strong, soluble reducing agents in a non-protic solvent, tetrahydrofuran (THF). With some exceptions, the particles obtained by room temperature reduction are random alloys that need to be annealed at modest temperatures (200 to 600 °C) in order to develop an ordered structure. To avoid significant particle size growth and agglomeration, the particles must be protected by surface coatings. We developed a novel method of coating the metal nanoparticles with KCl, a by-product of the reduction reaction if the proper reducing agents are employed. In that case, a composite product containing individual metal nanoparticles in a KCl matrix is obtained. The composite can be heated to at least 600 °C without significant agglomeration or growth in particle size. Washing the annealed product in the presence of catalyst supports in ethylene glycol removes the KCl and deposits the particles on the support. Six publications present the method and its application to producing and studying new catalyst/support combinations for fuel cell applications. Three publications concern the use of related methods to explore new lithium-sulfur battery concepts.

Computer simulations of disordering kinetics in irradiated intermetallic compounds

International Nuclear Information System (INIS)

Spaczer, M.; Caro, A.; Victoria, M.; Diaz de la Rubia, T.

1994-01-01

Molecular-dynamics computer simulations of collision cascades in intermetallic Cu 3 Au, Ni 3 Al, and NiAl have been performed to study the nature of the disordering processes in the collision cascade. The choice of these systems was suggested by the quite accurate description of the thermodynamic properties obtained using embedded-atom-type potentials. Since melting occurs in the core of the cascades, interesting effects appear as a result of the superposition of the loss (and subsequent recovery) of the crystalline order and the evolution of the chemical order, both processes being developed on different time scales. In our previous simulations on Ni 3 Al and Cu 3 Au [T. Diaz de la Rubia, A. Caro, and M. Spaczer, Phys. Rev. B 47, 11 483 (1993)] we found a significant difference between the time evolution of the chemical short-range order (SRO) and the crystalline order in the cascade core for both alloys, namely the complete loss of the crystalline structure but only partial chemical disordering. Recent computer simulations in NiAl show the same phenomena. To understand these features we study the liquid phase of these three alloys and present simulation results concerning the dynamical melting of small samples, examining the atomic mobility, the relaxation time, and the saturation value of the chemical short-range order. An analytic model for the time evolution of the SRO is given

Structure and properties of intermetallic ternary rare earth compounds

International Nuclear Information System (INIS)

Casper, Frederick

2008-01-01

The so called material science is an always growing field in modern research. For the development of new materials not only the experimental characterization but also theoretical calculation of the electronic structure plays an important role. A class of compounds that has attracted a great deal of attention in recent years is known as REME compounds. These compounds are often referred to with RE designating rare earth, actinide or an element from group 1-4, M representing a late transition metal from groups 8-12, and E belonging to groups 13-15. There are more than 2000 compounds with 1:1:1 stoichiometry belonging to this class of compounds and they offer a broad variety of different structure types. Although many REME compounds are know to exist, mainly only structure and magnetism has been determined for these compounds. In particular, in the field of electronic and transport properties relatively few efforts have been made. The main focus in this study is on compounds crystallizing in MgAgAs and LiGaGe structure. Both structures can only be found among 18 valence electron compounds. The f electrons are localized and therefor not count as valence electrons. A special focus here was also on the magnetoresistance effects and spintronic properties found among the REME compounds. An examination of the following compounds was made: GdAuE (E=In,Cd,Mg), GdPdSb, GdNiSb, REAuSn (RE=Gd,Er,Tm) and RENiBi (RE=Pr,Sm,Gd-Tm,Lu). The experimental results were compared with theoretic band structure calculations. The first half metallic ferromagnet with LiGaGe structure (GdPdSb) was found. All semiconducting REME compounds with MgAgAs structure show giant magnetoresistance (GMR) at low temperatures. The GMR is related to a metal-insulator transition, and the value of the GMR depends on the value of the spin-orbit coupling. Inhomogeneous DyNiBi samples show a small positive MR at low temperature that depends on the amount of metallic impurities. At higher fields the samples show a

Structure and properties of intermetallic ternary rare earth compounds

Energy Technology Data Exchange (ETDEWEB)

Casper, Frederick

2008-12-17

The so called material science is an always growing field in modern research. For the development of new materials not only the experimental characterization but also theoretical calculation of the electronic structure plays an important role. A class of compounds that has attracted a great deal of attention in recent years is known as REME compounds. These compounds are often referred to with RE designating rare earth, actinide or an element from group 1-4, M representing a late transition metal from groups 8-12, and E belonging to groups 13-15. There are more than 2000 compounds with 1:1:1 stoichiometry belonging to this class of compounds and they offer a broad variety of different structure types. Although many REME compounds are know to exist, mainly only structure and magnetism has been determined for these compounds. In particular, in the field of electronic and transport properties relatively few efforts have been made. The main focus in this study is on compounds crystallizing in MgAgAs and LiGaGe structure. Both structures can only be found among 18 valence electron compounds. The f electrons are localized and therefor not count as valence electrons. A special focus here was also on the magnetoresistance effects and spintronic properties found among the REME compounds. An examination of the following compounds was made: GdAuE (E=In,Cd,Mg), GdPdSb, GdNiSb, REAuSn (RE=Gd,Er,Tm) and RENiBi (RE=Pr,Sm,Gd-Tm,Lu). The experimental results were compared with theoretic band structure calculations. The first half metallic ferromagnet with LiGaGe structure (GdPdSb) was found. All semiconducting REME compounds with MgAgAs structure show giant magnetoresistance (GMR) at low temperatures. The GMR is related to a metal-insulator transition, and the value of the GMR depends on the value of the spin-orbit coupling. Inhomogeneous DyNiBi samples show a small positive MR at low temperature that depends on the amount of metallic impurities. At higher fields the samples show a

Development of heat resistant Pb-free joints by TLPS process of Ag and Sn-Bi-Ag alloy powders

Directory of Open Access Journals (Sweden)

Ohnuma I.

2012-01-01

Full Text Available TLPS (Transient Liquid Phase Sintering process is a candidate method of heat-resistant bonding, which makes use of the reaction between low-melting temperature powder of Sn-Bi base alloys and reactive powder of Ag. During heat treatment above the melting temperature of a Sn-Bi base alloy, the molten Sn-Bi reacts rapidly with solid Ag particles, which results in the formation of heat-resistant intermetallic compound (IMC. In this study, the TLPS properties between Sn-17Bi-1Ag (at.% powder with its liquidus temperature of 200°C and pure Ag powder were investigated. During differential scanning calorimetry (DSC measurement, an exothermic reaction and an endothermic reaction occurred, which correspond to the formation of the e-Ag3Sn IMC phase and the melting of the Sn-17Bi-1Ag alloy, respectively. After the overall measurement, the obtained reactant consists of the Ag3Sn-IMC and Bi-rich phases, both of which start melting above 250°C, with a small amount of the residual Sn-Bi eutectic phase. These results suggest that the TLPS process can be applied for Pb-free heatresistant bonding.

Formation of nickel-tantalum compounds in tantalum fluoride halide melts

International Nuclear Information System (INIS)

Matychenko, Eh.S.; Zalkind, O.A.; Kuznetsov, B.Ya.; Orlov, V.M.; Sukhorzhevskaya, S.L.

2001-01-01

Interaction of nickel with NaCl-K 2 TaF 7 melt (14 mol.%) at 750 deg C was studied, the composition of intermetallic compounds formed in Ni-Ta system being analyzed, using the methods of chemical and X-ray phase analyses, IR spectroscopy. It was ascertained that composition of intermetallic compounds (Ni 3 Ta, Ni 2 Ta) depends on K 2 TaF 7 concentration in the melt, metallic tantalum additions, nickel substrate thickness and experiment duration. The mechanism of currentless deposition of tantalum on nickel was considered and the assumption was made that disproportionation reaction lies in the basis of the process [ru

Solid state synthesis, structural, physicochemical and optical properties of an inter-molecular compound: 2-hydroxy-1, 2-diphenylethanone-4-nitro-o-phenylenediamine system

Science.gov (United States)

Rai, U. S.; Singh, Manjeet; Rai, R. N.

2017-09-01

The phase diagram of 2-hydroxy-1, 2-diphenylethanone (HDPE)-4-nitro-o-phenylenediamine (NOPDA) system, determined by the thaw-melt method, gives two eutectics E1 (m p = 66.0 °C) and E2 (m p = 155.0 °C) with 0.30 and 0.55 mol fractions of NOPDA, respectively, and an 1:1 inter-molecular compound (IMC) (m p 162.0 °C). This IMC was synthesized by adopting the green synthetic method of solid state reaction. While its formation and structure were confirmed by the X-ray diffraction and spectroscopic methods, the ORTEP view gives mode of crystal packing, C‒H…O, C‒H…N, π-π stacking and the inter-molecular hydrogen bonding in the compound. The single crystal of the IMC shows 53% transmission and emits significantly higher dual fluorescence, and the band gap was computed to be 3.04 eV. The values of solubility of the IMC, measured in the temperature range 304-322 K, satisfy the mole fraction (X) and temperature equation: Xeq= 5.1324 × 10-7 e 0.01356T.

Development of Bi-base high-temperature Pb-free solders with second-phase dispersion: Thermodynamic calculation, microstructure, and interfacial reaction

Science.gov (United States)

Takaku, Yoshikazu; Ohnuma, Ikuo; Kainuma, Ryosuke; Yamada, Yasushi; Yagi, Yuji; Nishibe, Yuji; Ishida, Kiyohito

2006-11-01

Bismuth and its alloys are candidates for Pb-free high-temperature solders that can be substituted for conventional Pb-rich Pb-Sn solders (melting point (mp) = 573 583 K). However, inferior properties such as brittleness and weak bonding strength should be improved for practical use. To that end, BiCu-X (X=Sb, Sn, and Zn) Pb-free high-temperature solders are proposed. Miscibility gaps in liquid BiCu-X alloys were surveyed using the thermodynamic database ADAMIS (alloy database for micro-solders), and compositions of the BiCu-X solders were designed on the basis of calculation. In-situ composite solders that consist of a Bi-base matrix with fine intermetallic compound (IMC) particles were produced by gas-atomizing and melt-spinning methods. The interfacial reaction between in-situ composite solders and Cu or Ni substrates was investigated. The IMCs at the interface formed a thin, uniform layer, which is an appropriate morphology for a reliable solder joint.

Effect of Brass Interlayer Sheet on Microstructure and Joint Performance of Ultrasonic Spot-Welded Copper-Steel Joints

Science.gov (United States)

Satpathy, Mantra Prasad; Kumar, Abhishek; Sahoo, Susanta Kumar

2017-07-01

Solid-state ultrasonic spot welding (USW) inevitably offers a potential solution for joining dissimilar metal combination like copper (Cu) and steel (SS). In this study, the USW has been performed on Cu (UNS C10100) and SS (AISI 304) with brass interlayer by varying various welding parameters, aiming to identify the interfacial reaction, changes in microstructure and weld strength. The highest tensile shear and T-peel failure loads of 1277 and 174 N are achieved at the optimum conditions like 68 µm of vibration amplitude, 0.42 MPa of weld pressure and 1 s of weld time. The fractured surface analysis of brass interlayer and AISI 304 stainless steel samples reveals the features like swirls, voids and intermetallic compounds (IMCs). These IMCs are composed of CuZn and FeZn composite-like structures with 1.0 μm thickness. This confirms that the weld quality is specifically sensitive to the levels of input parameter combinations as well as the type of material present on the sonotrode side.

Forecasting of superconducting compounds

International Nuclear Information System (INIS)

Savitskii, E.M.; Gribulya, V.G.; Kiseleva, N.N.

1981-01-01

In forecasting new superconducting intermetallic compounds of the A15 and Mo 3 Se types most promising from the viewpoint of high critical temperature Tsub(c), high critical magnetic fields Hsub(c), and high critical currents and in estimating their transition temperature it is proposed to apply cybernetic methods of computer learning

A diffraction based study of the deformation mechanisms in anomalously ductile B2 intermetallics

Science.gov (United States)

Mulay, Rupalee Prashant

For many decades, the brittle nature of most intermetallic compounds (e.g. NiAl) has been the limiting factor in their practical application. Many B2 (CsCl prototypical structure) intermetallics are known to exhibit slip on the {110} slip mode, which provides only 3 independent slip systems and, hence, is unable to satisfy the von Mises (a.k.a. Taylor) criterion for polycrystalline ductility. As a result, inherent polycrystalline ductility is unexpected. Recent discovery of a number of ductile B2 intermetallics has raised questions about possible violation of the von Mises criterion by these alloys. These ductile intermetallic compounds are MR (metal (M) combined with a rare earth metal or group IV refractory metal (R)) alloys and are stoichiometric, ordered compounds. Single crystal slip trace analyses have only identified the presence of {011} or {010} slip systems. More than 100 other B2 MR compounds are known to exist and many of them have already been shown to be ductile (e.g., CuY, AgY, CuDy, CoZr, CoTi, etc.). Furthermore, these alloys exhibit a large Bauschinger effect. The present work uses several diffraction based techniques including electron back scattered diffraction (EBSD), X-ray diffraction (XRD) and in-situ neutron diffraction; in conjunction with scanning electron microscopy (SEM), transmission electron microscopy (TEM), mechanical testing, and crystal plasticity modeling, to elucidate the reason for ductility in select B2 alloys, explore the spread of this ductility over the B2 family, and understand the Bauschinger effect in these alloys. Several possible explanations (e.g., slip of dislocations, strong texture, phase transformations and twinning) for the anomalous ductility were explored. An X-ray diffraction based analysis ruled out texture, phase purity and departure from order as explanations for the anomalous ductility in MR alloys. In-situ neutron diffraction and post deformation SEM, EBSD, and TEM were unable to detect any evidence for

Effect of rapid quenching on the magnetism and magnetocaloric effect of equiatomic rare earth intermetallic compounds RNi (R = Gd, Tb and Ho)

Energy Technology Data Exchange (ETDEWEB)

Rajivgandhi, R. [Department of Physics, Indian Institute of Technology Madras, Chennai 600 036 (India); Arout Chelvane, J. [Defence Metallurgical Research Laboratory, Hyderabad 500 058 (India); Quezado, S.; Malik, S.K. [Departamento de F’ısica Teorica e Experimental, Universidade Federal do Rio Grande do Norte, Natal 59072-970 (Brazil); Nirmala, R., E-mail: nirmala@physics.iitm.ac.in [Department of Physics, Indian Institute of Technology Madras, Chennai 600 036 (India)

2017-07-01

Highlights: • Melt-spinning yields microcrystalline RNi (R = Gd, Tb and Ho) samples with texture. • The texture-induced anisotropy affects magnetic and magnetocaloric properties. • Melt-spinning helps one engineer magnetocaloric effect in rare-earth compounds. - Abstract: Magnetocaloric effect (MCE) in RNi (where R = Gd, Tb and Ho) compounds has been studied in their arc-melted and melt-spun forms. The compound GdNi has the orthorhombic CrB-type structure (Space group Cmcm, No. 63) and the compound HoNi has the orthorhombic FeB-type structure (Space group Pnma, No. 62) at room temperature regardless of their synthesis condition. However, arc-melted TbNi orders in a monoclinic structure (Space group P2{sub 1}/m, No. 11) and when it is rapidly quenched to a melt-spun form, it crystallizes in an orthorhombic structure (Space group Pnma, No. 62). The arc-melted GdNi, TbNi and HoNi compounds order ferromagnetically at ∼69 K, ∼67 K and ∼36 K (T{sub C}) respectively. While the melt-spun GdNi shows about 6 K increase in T{sub C}, the ordering temperature of TbNi remains nearly the same in both arc-melted and melt-spun forms. In contrast, a reduction in T{sub C} by about 8 K is observed in melt-spun HoNi, when compared to its arc-melted counterpart. Isothermal magnetic entropy change, ∆S{sub m}, calculated from the field dependent magnetization data indicates an enhanced relative cooling power (RCP) for melt-spun GdNi for field changes of 20 kOe and 50 kOe. A lowered RCP value is observed in melt-spun TbNi and HoNi. These changes could have resulted from the competing shape anisotropy and the granular microstructure induced by the melt-spinning process. Tailoring the MCE of rare earth intermetallic compounds by suitably controlled synthesis techniques is certainly one of the directions to go forward in the search of giant magnetocaloric materials.

Effect of buckwheat flour and oat bran on growth and cell viability of the probiotic strains Lactobacillus rhamnosus IMC 501®, Lactobacillus paracasei IMC 502® and their combination SYNBIO®, in synbiotic fermented milk.

Science.gov (United States)

Coman, Maria Magdalena; Verdenelli, Maria Cristina; Cecchini, Cinzia; Silvi, Stefania; Vasile, Aida; Bahrim, Gabriela Elena; Orpianesi, Carla; Cresci, Alberto

2013-10-15

Fermented foods have a great significance since they provide and preserve large quantities of nutritious foods in a wide diversity of flavors, aromas and texture, which enrich the human diet. Originally fermented milks were developed as a means of preserving nutrients and are the most representatives of the category. The first aim of this study was to screen the effect of buckwheat flour and oat bran as prebiotics on the production of probiotic fiber-enriched fermented milks, by investigating the kinetics of acidification of buckwheat flour- and oat bran-supplemented milk fermented by Lactobacillus rhamnosus IMC 501®, Lactobacillus paracasei IMC 502® and their 1:1 combination named SYNBIO®. The probiotic strains viability, pH and sensory characteristics of the fermented fiber-enriched milk products, stored at 4 °C for 28 days were also monitored. The results showed that supplementation of whole milk with the tested probiotic strains and the two vegetable substrates results in a significant faster lowering of the pH. Also, the stability of L. rhamnosus IMC 501®, L. paracasei IMC 502® and SYNBIO® during storage at 4 °C for 28 days in buckwheat flour- and oat bran-supplemented samples was remarkably enhanced. The second aim of the study was to develop a new synbiotic product using the best combination of probiotics and prebiotics by promoting better growth and survival and be acceptable to the consumers with high concentration of probiotic strain. This new product was used to conduct a human feeding trial to validate the fermented milk as a carrier for transporting bacterial cells into the human gastrointestinal tract. The probiotic strains were recovered from fecal samples in 40 out of 40 volunteers fed for 4 weeks one portion per day of synbiotic fermented milk carrying about 10(9) viable cells. © 2013.

The Effect of CuSn Intermetallics on the Interstrand Contact Resistance in Superconducting Cables for the Large Hadron Collider (LHC)

CERN Document Server

Scheuerlein, C; Jacob, P; Leroy, D; Oberli, L R; Taborelli, M

2005-01-01

The LHC superconducting cables are submitted to a 200°C heat-treatment in air in order to increase the resistance between the crossing strands (RC) within the cable. During this treatment the as-applied Sn-Ag alloy strand coating is transformed into a CuSn intermetallic compound layer. The microstructure, the surface topography and the surface chemistry of the non-reacted and reacted coatings have been characterised by different techniques, notably focused ion beam (FIB), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). Based on the results obtained by these techniques the different influences that the intermetallics have on RC are discussed. The desired RC is obtained only when a continuous Cu3Sn layer is formed, i.e. a sufficient wetting of the Cu substrate by the tinning alloy is crucial. Among other effects the formation of the comparatively hard intermetallics roughens the surface and, thus, reduces the true contact area and i...

IMC DOS ALUNOS DO 4º PERÍODO DO CURSO TÉCNICO EM ALIMENTOS DO INSTITUTO FEDERAL DE GOIÁS CAMPI/INHUMAS.

Directory of Open Access Journals (Sweden)

Jefferson Jorcelino Máximo

2011-03-01

Full Text Available Introdução: O índice de massa corpórea – IMC é uma medida simples do grau de obesidade de um indivíduo, sendo utilizada para mensurar o nível de adiposidade em estudos populacionais. Com isso, tem se verificado que a obesidade está se tornando um dos maiores problemas de saúde pública, pois está intimamente associada a incidência de doenças cardiovasculares. Objetivo: Analisar o índice de massa corpórea dos alunos do 4º período do curso técnico em alimentos. Método: Dezenove (19 alunos com idade entre 18 e 46 anos foram submetidos a avaliação biométrica (massa corporal e estatura. Para o cálculo do IMC foi utilizado o índice de Quetelet (Peso/Altura² peso em quilogramas dividido pela altura em metros ao quadrado, sendo que desses, 17 do sexo feminino e 02 do sexo masculino. Resultado: Os resultados obtidos pela amostra foram classificados nas categorias de IMC < 20 Abaixo do peso; IMC 20 a 25 Kg/m² Peso Normal; IMC 25,1 a 29,9 Kg/m² Sobrepeso; IMC 30,0 a 39,9 Kg/m² Obeso e < 40 Kg/m² Obeso Mórbido. Classificação segundo a Organização Mundial de Saúde OMS.

Integrated Marketing Communication (Imc) Green Radio 96,7 Fm Pekanbaru Dalam Membangun Brand Image Sebagai Media Berbasis Lingkungan

OpenAIRE

Marbun, Tresia Br; ", Rumyeni

2017-01-01

Integrated Marketing Communication (IMC) is the company's effort to integrate and coordinate all communication channels to deliver its message clearly, consistently and strongly influences its organization and products. Green Radio 96.7 FM Pekanbaru is the only electronic media that focuses on broadcasting news Environmental issues in Riau Province. This radio builds brand image as an environment-based media by choosing to use Integrated Marketing Communication (IMC). This study aims to find ...

Hybridization and pressure effects in UTX compounds

Czech Academy of Sciences Publication Activity Database

Alsmadi, A. M.; Sechovský, V.; Lacerda, A. H.; Prokes, K.; Kamarád, Jiří; Chang, S.; Jung, M. H.; Nakotte, H.

2002-01-01

Roč. 91, - (2002), s. 8123-8125 ISSN 0021-8979 Institutional research plan: CEZ:AV0Z1010914 Keywords : UTX intermetallic compounds * pressure effects magnetoresistance Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.281, year: 2002

Understanding the development and diffusion of integrated marketing communications (IMC) : A metaphorical perspective

NARCIS (Netherlands)

Cornelissen, J.P.; Thøger, L.; Vijn, P.

2006-01-01

In recent years, theoretical commentaries and empirical research on the concept of Integrated Marketing Communications (IMC) have been concerned with its development and specification as a theoretical construct, and its diffusion among academics and practitioner populations across the globe. In this

The atomic structure of low-index surfaces of the intermetallic compound InPd

Energy Technology Data Exchange (ETDEWEB)

McGuirk, G. M.; Ledieu, J.; Gaudry, É.; Weerd, M.-C.; Fournée, V. de, E-mail: vincent.fournee@univ-lorraine.fr [Institut Jean Lamour (UMR 7198 CNRS-Université de Lorraine), Parc de Saurupt, F-54011 Nancy Cedex (France); Hahne, M.; Gille, P. [Department of Earth and Environmental Sciences, Crystallography Section, Ludwig-Maximilians-Universität München, Theresienstrasse 41, D-80333 München (Germany); Ivarsson, D. C. A.; Armbrüster, M. [Faculty of Natural Sciences, Institute of Chemistry, Materials for Innovative Energy Concepts, Technische Universität Chemnitz, D-09107 Chemnitz (Germany); Ardini, J.; Held, G. [Department of Chemistry, University of Reading, Reading RG6 6AD (United Kingdom); Diamond Light Source Ltd, Didcot OX11 0DE (United Kingdom); Maccherozzi, F. [Diamond Light Source Ltd, Didcot OX11 0DE (United Kingdom); Bayer, A. [Lehrstuhl für Physikalische Chemie II, Universität Erlangen-Nürnberg, Egerlandstraße 3, D-91058 Erlangen (Germany); Lowe, M. [Surface Science Research Centre and Department of Physics, The University of Liverpool, Liverpool L69 3BX (United Kingdom); Pussi, K. [Department of Mathematics and Physics, Lappeenranta University of Technology, P.O. Box 20, FIN-53851 Lappeenranta (Finland); Diehl, R. D. [Department of Physics, Penn State University, University Park, Pennsylvania 16802 (United States)

2015-08-21

The intermetallic compound InPd (CsCl type of crystal structure with a broad compositional range) is considered as a candidate catalyst for the steam reforming of methanol. Single crystals of this phase have been grown to study the structure of its three low-index surfaces under ultra-high vacuum conditions, using low energy electron diffraction (LEED), X-ray photoemission spectroscopy (XPS), and scanning tunneling microscopy (STM). During surface preparation, preferential sputtering leads to a depletion of In within the top few layers for all three surfaces. The near-surface regions remain slightly Pd-rich until annealing to ∼580 K. A transition occurs between 580 and 660 K where In segregates towards the surface and the near-surface regions become slightly In-rich above ∼660 K. This transition is accompanied by a sharpening of LEED patterns and formation of flat step-terrace morphology, as observed by STM. Several superstructures have been identified for the different surfaces associated with this process. Annealing to higher temperatures (≥750 K) leads to faceting via thermal etching as shown for the (110) surface, with a bulk In composition close to the In-rich limit of the existence domain of the cubic phase. The Pd-rich InPd(111) is found to be consistent with a Pd-terminated bulk truncation model as shown by dynamical LEED analysis while, after annealing at higher temperature, the In-rich InPd(111) is consistent with an In-terminated bulk truncation, in agreement with density functional theory (DFT) calculations of the relative surface energies. More complex surface structures are observed for the (100) surface. Additionally, individual grains of a polycrystalline sample are characterized by micro-spot XPS and LEED as well as low-energy electron microscopy. Results from both individual grains and “global” measurements are interpreted based on comparison to our single crystals findings, DFT calculations and previous literature.

Microstructural discovery of Al addition on Sn–0.5Cu-based Pb-free solder design

International Nuclear Information System (INIS)

Koo, Jahyun; Lee, Changsoo; Hong, Sung Jea; Kim, Keun-Soo; Lee, Hyuck Mo

2015-01-01

It is important to develop Pb-free solder alloys suitable for automotive use instead of traditional Sn–Pb solder due to environmental regulations (e.g., Restriction of Hazardous Substances (RoHS)). Al addition has been spotlighted to enhance solder properties. In this study, we investigated the microstructural change of Sn–0.5Cu wt.% based Pb-free solder alloys with Al addition (0.01–0.05 wt.%). The small amount of Al addition caused a remarkable microstructural change. The Al was favored to form Cu–Al intermetallic compounds inside the solder matrix. We identified the Cu–Al intermetallic compound as Cu_3_3Al_1_7, which has a rhombohedral structure, using EPMA and TEM analyses. This resulted in refined Cu_6Sn_5 networks in the Sn–0.5Cu based solder alloy. In addition, we conducted thermal analysis to confirm its stability at a high temperature of approximately 230 °C, which is the necessary temperature range for automotive applications. The solidification results were substantiated thermodynamically using the Scheil solidification model. We can provide criteria for the minimum aluminum content to modify the microstructure of Pb-free solder alloys. - Graphical abstract: The minor Al additions refined eutectic Cu_6Sn_5 IMC networks on the Sn–0.5Cu based solder alloys. The microstructure was dramatically changed with the minor Al addition. - Highlights: • We observed dramatic microstructure-change with Al additions. • We defined Cu_3_3Al_1_7 IMC with Al additions using TEM analysis. • We investigated grain refinement with Al additions using EBSD. • We discussed the refinement based on Scheil solidification model.

Microstructural discovery of Al addition on Sn–0.5Cu-based Pb-free solder design

Energy Technology Data Exchange (ETDEWEB)

Koo, Jahyun; Lee, Changsoo [Department of Materials Science and Engineering, KAIST, Daejeon 305-701 (Korea, Republic of); Hong, Sung Jea [MK Electron Co., Ltd., Yongin Cheoin-gu 316-2 (Korea, Republic of); Kim, Keun-Soo, E-mail: keunsookim@hoseo.edu [Department of Display Engineering, Hoseo University, Asan 336-795 (Korea, Republic of); Lee, Hyuck Mo, E-mail: hmlee@kaist.ac.kr [Department of Materials Science and Engineering, KAIST, Daejeon 305-701 (Korea, Republic of)

2015-11-25

It is important to develop Pb-free solder alloys suitable for automotive use instead of traditional Sn–Pb solder due to environmental regulations (e.g., Restriction of Hazardous Substances (RoHS)). Al addition has been spotlighted to enhance solder properties. In this study, we investigated the microstructural change of Sn–0.5Cu wt.% based Pb-free solder alloys with Al addition (0.01–0.05 wt.%). The small amount of Al addition caused a remarkable microstructural change. The Al was favored to form Cu–Al intermetallic compounds inside the solder matrix. We identified the Cu–Al intermetallic compound as Cu{sub 33}Al{sub 17}, which has a rhombohedral structure, using EPMA and TEM analyses. This resulted in refined Cu{sub 6}Sn{sub 5} networks in the Sn–0.5Cu based solder alloy. In addition, we conducted thermal analysis to confirm its stability at a high temperature of approximately 230 °C, which is the necessary temperature range for automotive applications. The solidification results were substantiated thermodynamically using the Scheil solidification model. We can provide criteria for the minimum aluminum content to modify the microstructure of Pb-free solder alloys. - Graphical abstract: The minor Al additions refined eutectic Cu{sub 6}Sn{sub 5} IMC networks on the Sn–0.5Cu based solder alloys. The microstructure was dramatically changed with the minor Al addition. - Highlights: • We observed dramatic microstructure-change with Al additions. • We defined Cu{sub 33}Al{sub 17} IMC with Al additions using TEM analysis. • We investigated grain refinement with Al additions using EBSD. • We discussed the refinement based on Scheil solidification model.

New ternary intermetallics, based magnesium, for hydrogen storage

International Nuclear Information System (INIS)

Roquefere, J.G.

2009-05-01

The use of fossil fuels (non-renewable energy) is responsible for increasing the concentration of greenhouse gases in the atmosphere. Among the considered alternatives, hydrogen is seen as the most attractive energy vector. The storage in intermetallics makes it possible to obtain mass and volume capacities (e.g. 140 g/L) higher than those obtained by liquid form or under pressure (respectively 71 and 40 g/L). We have synthesised Mg and Rare Earth based compounds (RE = Y, Ce and Gd), derived from the cubic Laves phases AB2. Their physical and chemical properties have been studied (hydrogenation, electrochemistry, magnetism,...). The conditions of sorption (P and T) are particularly favorable (i.e. absorption at room temperature and atmospheric pressure). Besides, to improve the sorption kinetics of metallic magnesium, the compounds developed previously were used as catalysts. Thus, GdMgNi4 was milled with magnesium and the speeds of absorption and desorption of the mixture are found higher than those obtained for the composites Mg+Ni or Mg+V, which are reference systems. A theoretical approach (DFT) was used to model the electronic structure of the ternary compounds (i.e. REMgNi4) and thus to predict or confirm the experimental results. (authors)

Electrocatalytic hydride-forming compounds for rechageable batteries

NARCIS (Netherlands)

Notten, P.H.L.; Einerhand, R.E.F.

1991-01-01

Non-toxic intermetallic hydride-forming compounds are attractive alternatives to cadmium as the negative electrode materials in the new generation of Ni/metal hydride rechargeable batteries. High exchange currents and discharge efficiencies even at low temperatures can be achieved using highly

ASSOCIAÇÃO ENTRE O ÍNDICE DE ADIPOSIDADE CORPORAL (IAC E ÍNDICE DE MASSA CORPORAL (IMC EM MULHERES PRATICANTES DE TREINAMENTO RESISTIDO

Directory of Open Access Journals (Sweden)

William Cordeiro de Souza

2014-04-01

Full Text Available O presente estudo buscou como objetivo realizar uma relação entre o índice de adiposidade corporal (IAC e índice de massa corporal (IMC em mulheres praticantes de treinamento resistido. A mostra foi composta por 14 mulheres (idade: 27 ± 3.96 anos praticantes de treinamento resistido (3 a 5 dias por semana. Foram avaliados o peso e a estatura para obtenção de IMC e circunferência do quadril (CQ na determinação do índice de adiposidade corporal. Na análise dos dados foi utilizada à estatística descritiva: Média, desvio padrão (dp, frequência percentual (% e o fator de correlação de Pearson (r com nível de significância de 0,05. Nos resultados obtidos observou-se que no IMC todas as avaliadas estão dentro dos padrões estabelecidos (eutroficas. Com relação ao IAC, 28.57% (n=4 das mulheres avaliadas estão dentro do padrão “Ideal”, 42.87% (n=6 com seu percentual “Moderado” e 28.57% (n= 4 com “Excesso de gordura”. Quanto à circunferência do quadril foi verificado que as todas as avaliadas (n=14 estão com dentro dos padrões recomendo. Não foram encontradas correlações entre IMC e IAC (r =0,392 e p =0,164, nem entre IMC e CQ (r =0,272 e p =0,345. Ao finalizar o estudo foi verificado que não houve diferenças significativas entre IMC e IAC; nem para o IMC com a CQ.

Magnetization and specific heat study of metamagnetism in Lu.sub.2./sub.Fe.sub.17./sub.-based intermetallic compounds

Czech Academy of Sciences Publication Activity Database

Tereshina, Evgeniya; Andreev, Alexander V.

2010-01-01

Roč. 18, č. 6 (2010), 1205-1210 ISSN 0966-9795 R&D Projects: GA ČR GA202/09/0339 Institutional research plan: CEZ:AV0Z10100520 Keywords : rare-earth intermetallics * magnetic properties * single crystal growth Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.327, year: 2010

Nutrient modeling for a semi-intensive IMC pond: an MS-Excel approach.

Science.gov (United States)

Ray, Lala I P; Mal, B C; Moulick, S

2017-11-01

Semi-intensive Indian Major Carp (IMC) culture was practised in polythene lined dugout ponds at the Aquacultural Farm of Indian Institute of Technology, Kharagpur, West Bengal for 3 consecutive years at three different stocking densities (S.D), viz., 20,000, 35,000 and 50,000 numbers of fingerlings per hectare of water spread area. Fingerlings of Catla, Rohu and Mrigal were raised at a stocking ratio of 4:3:3. Total ammonia nitrogen (TAN) value along with other fishpond water quality parameters was monitored at 1 day intervals to ensure a good water ecosystem for a better fish growth. Water exchange was carried out before the TAN reached the critical limit. Field data on TAN obtained from the cultured fishponds stocked with three different stocking densities were used to study the dynamics of TAN. A developed model used to study the nutrient dynamics in shrimp pond was used to validate the observed data in the IMC pond ecosystem. Two years of observed TAN data were used to calibrate the spreadsheet model and the same model was validated using the third year observed data. The manual calibration based on the trial and error process of parameters adjustments was used and several simulations were performed by changing the model parameters. After adjustment of each parameter, the simulated and measured values of the water quality parameters were compared to judge the improvement in the model prediction. Forward finite difference discretization method was used in a MS-Excel spreadsheet to calibrate and validate the model for obtaining the TAN levels during the culture period. Observed data from the cultured fishponds of three different S.D were used to standardize 13 model parameters. The efficiency of the developed spreadsheet model was found to be more than 90% for the TAN estimation in the IMC cultured fishponds.

Laves intermetallics in stainless steel-zirconium alloys

International Nuclear Information System (INIS)

Abraham, D.P.; McDeavitt, S.M.; Richardson, J.W. Jr.

1997-01-01

Laves intermetallics have a significant effect on properties of metal waste forms being developed at Argonne National Laboratory. These waste forms are stainless steel-zirconium alloys that will contain radioactive metal isotopes isolated from spent nuclear fuel by electrometallurgical treatment. The baseline waste form composition for stainless steel-clad fuels is stainless steel-15 wt.% zirconium (SS-15Zr). This article presents results of neutron diffraction measurements, heat-treatment studies and mechanical testing on SS-15Zr alloys. The Laves intermetallics in these alloys, labeled Zr(Fe,Cr,Ni) 2+x , have both C36 and C15 crystal structures. A fraction of these intermetallics transform into (Fe,Cr,Ni) 23 Zr 6 during high-temperature annealing; the authors have proposed a mechanism for this transformation. The SS-15Zr alloys show virtually no elongation in uniaxial tension, but exhibit good strength and ductility in compression tests. This article also presents neutron diffraction and microstructural data for a stainless steel-42 wt.% zirconium (SS-42Zr) alloy

Comparative Study of ENIG and ENEPIG as Surface Finishes for a Sn-Ag-Cu Solder Joint

Science.gov (United States)

Yoon, Jeong-Won; Noh, Bo-In; Jung, Seung-Boo

2011-09-01

Interfacial reactions and joint reliability of Sn-3.0Ag-0.5Cu solder with two different surface finishes, electroless nickel-immersion gold (ENIG) and electroless nickel-electroless palladium-immersion gold (ENEPIG), were evaluated during a reflow process. We first compared the interfacial reactions of the two solder joints and also successfully revealed a connection between the interfacial reaction behavior and mechanical reliability. The Sn-Ag-Cu/ENIG joint exhibited a higher intermetallic compound (IMC) growth rate and a higher consumption rate of the Ni(P) layer than the Sn-Ag-Cu/ENEPIG joint. The presence of the Pd layer in the ENEPIG suppressed the growth of the interfacial IMC layer and the consumption of the Ni(P) layer, resulting in the superior interfacial stability of the solder joint. The shear test results show that the ENIG joint fractured along the interface, exhibiting indications of brittle failure possibly due to the brittle IMC layer. In contrast, the failure of the ENEPIG joint only went through the bulk solder, supporting the idea that the interface is mechanically reliable. The results from this study confirm that the Sn-Ag-Cu/ENEPIG solder joint is mechanically robust and, thus, the combination is a viable option for a Pb-free package system.

Magnetic phase transitions in R2Fe17 compounds under pressure

International Nuclear Information System (INIS)

Arnold, Z.; Kamarad, J.

1994-01-01

The effect of the pressure up to 1.4 GPa on the Curie temperature T c in the R 2 Fe 17 intermetallics with R = Nd, Er and Y was measured using a low field susceptibility technique. The identical character of the temperature dependence of susceptibility χ(T) of the R 2 Fe 17 intermetallics observed at ambient pressure (sharp step-like drop at T c ) is preserved at high pressures only in the case of Nd 2 Fe 17 . Pronounced broadening and splitting of the sharp drop of χ(T) was observed in Er 2 Fe 17 and Y 2 Fe 17 respectively. The initial pressure slopes of dTc/dp are large and negative for all studied compounds, having nearly the same values (dTc/dp = -36K/GPa for Nd 2 Fe 17 compound). The results are discussed from the point of view of the sensitivity of T c on the crystal structure, the number of nearest neighbors of Fe atoms and the possible effect of disordered structures in the R 2 Fe 17 intermetallics

Microstructure and Tensile Properties of Sn-1Ag-0.5Cu Solder Alloy Bearing Al for Electronics Applications

Science.gov (United States)

Shnawah, Dhafer Abdul-Ameer; Said, Suhana Binti Mohd; Sabri, Mohd Faizul Mohd; Badruddin, Irfan Anjum; Hoe, Teh Guan; Che, Fa Xing; Abood, Adnan Naama

2012-08-01

This work investigates the effects of 0.1 wt.% and 0.5 wt.% Al additions on bulk alloy microstructure and tensile properties as well as on the thermal behavior of Sn-1Ag-0.5Cu (SAC105) lead-free solder alloy. The addition of 0.1 wt.% Al reduces the amount of Ag3Sn intermetallic compound (IMC) particles and leads to the formation of larger ternary Sn-Ag-Al IMC particles. However, the addition of 0.5 wt.% Al suppresses the formation of Ag3Sn IMC particles and leads to a large amount of fine Al-Ag IMC particles. Moreover, both 0.1 wt.% and 0.5 wt.% Al additions suppress the formation of Cu6Sn5 IMC particles and lead to the formation of larger Al-Cu IMC particles. The 0.1 wt.% Al-added solder shows a microstructure with coarse β-Sn dendrites. However, the addition of 0.5 wt.% Al has a great effect on suppressing the undercooling and refinement of the β-Sn dendrites. In addition to coarse β-Sn dendrites, the formation of large Sn-Ag-Al and Al-Cu IMC particles significantly reduces the elastic modulus and yield strength for the SAC105 alloy containing 0.1 wt.% Al. On the other hand, the fine β-Sn dendrite and the second-phase dispersion strengthening mechanism through the formation of fine Al-Ag IMC particles significantly increases the elastic modulus and yield strength of the SAC105 alloy containing 0.5 wt.% Al. Moreover, both 0.1 wt.% and 0.5 wt.% Al additions worsen the elongation. However, the reduction in elongation is much stronger, and brittle fracture occurs instead of ductile fracture, with 0.5 wt.% Al addition. The two additions of Al increase both solidus and liquidus temperatures. With 0.5 wt.% Al addition the pasty range is significantly reduced and the differential scanning calorimetry (DSC) endotherm curve gradually shifts from a dual to a single endothermic peak.

Summer Project on Exponential Convergence for IMC

Energy Technology Data Exchange (ETDEWEB)

Gentile, N [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2016-05-23

I want to look at modifying the Morel and Bolding algorithm in two ways. One is to remove the need to represent the intensity in a deterministic form and for a deterministic representation of a transport operator. The second is to look at representing the moments of the source with a simpler form that doesn’t require as many terms. Morel and Bolding also didn’t include scattering in their stuff. IMC has a lot of scattering occurring because of the effective scatters. I think that scattering can be added to the method, but I think that will require more than a summer’s worth of work. So we’ll just ignore scattering, and just look at problems with a huge c_v so that there is no effective scattering.

Summer Project on Exponential Convergence for IMC

International Nuclear Information System (INIS)

Gentile, N

2016-01-01

I want to look at modifying the Morel and Bolding algorithm in two ways. One is to remove the need to represent the intensity in a deterministic form and for a deterministic representation of a transport operator. The second is to look at representing the moments of the source with a simpler form that doesn't require as many terms. Morel and Bolding also didn't include scattering in their stuff. IMC has a lot of scattering occurring because of the effective scatters. I think that scattering can be added to the method, but I think that will require more than a summer's worth of work. So we'll just ignore scattering, and just look at problems with a huge c v so that there is no effective scattering.

Electronic and optical properties of RESn{sub 3} (RE=Pr & Nd) intermetallics: A first principles study

Energy Technology Data Exchange (ETDEWEB)

Pagare, G., E-mail: gita-pagare@yahoo.co.in [Department of Physics, Government M. L. B. Girls P. G. Autonomous College, Bhopal-462002 (India); Abraham, Jisha A. [Department of Physics, Government M. L. B. Girls P. G. Autonomous College, Bhopal-462002 (India); Department of Physics, National Defence Academy, Pune-411023 (India); Sanyal, S. P. [Department of Physics, Barkatullah University, Bhopal-462026 (India)

2015-06-24

A theoretical study of structural, electronic and optical properties of RESn{sub 3} (RE = Pr & Nd) intermetallics have been investigated systematically using first principles density functional theory. The calculations are carried out within the PBE-GGA and LSDA for the exchange correlation potential. The ground state properties such as lattice parameter (a{sub 0}), bulk modulus (B) and its pressure derivative (B′) are calculated and the calculated lattice parameters show well agreement with the experimental results. We first time predict elastic constants for these compounds. From energy dispersion curves, it is found that these compounds are metallic in nature. The linear optical response of these compounds are also studied and the higher value of static dielectric constant shows the possibility to use them as good dielectric materials.

Stabilization of Teleoperation Systems with Communication Delays: An IMC Approach

Directory of Open Access Journals (Sweden)

Yuling Li

2018-01-01

Full Text Available The presence of time delays in communication introduces a limitation to the stability of bilateral teleoperation systems. This paper considers internal model control (IMC design of linear teleoperation system with time delays, and the stability of the closed-loop system is analyzed. It is shown that the stability is guaranteed delay-independently. The passivity assumption for external forces is removed for the proposed design of teleoperation systems. The behavior of the resulting teleoperation system is illustrated by simulations.

Effect of dual laser beam on dissimilar welding-brazing of aluminum to galvanized steel

Science.gov (United States)

Mohammadpour, Masoud; Yazdian, Nima; Yang, Guang; Wang, Hui-Ping; Carlson, Blair; Kovacevic, Radovan

2018-01-01

In this investigation, the joining of two types of galvanized steel and Al6022 aluminum alloy in a coach peel configuration was carried out using a laser welding-brazing process in dual-beam mode. The feasibility of this method to obtain a sound and uniform brazed bead with high surface quality at a high welding speed was investigated by employing AlSi12 as a consumable material. The effects of alloying elements on the thickness of intermetallic compound (IMC) produced at the interface of steel and aluminum, surface roughness, edge straightness and the tensile strength of the resultant joint were studied. The comprehensive study was conducted on the microstructure of joints by means of a scanning electron microscopy and EDS. Results showed that a dual-beam laser shape and high scanning speed could control the thickness of IMC as thin as 3 μm and alter the failure location from the steel-brazed interface toward the Al-brazed interface. The numerical simulation of thermal regime was conducted by the Finite Element Method (FEM), and simulation results were validated through comparative experimental data. FEM thermal modeling evidenced that the peak temperatures at the Al-steel interface were around the critical temperature range of 700-900 °C that is required for the highest growth rate of IMC. However, the time duration that the molten pool was placed inside this temperature range was less than 1 s, and this duration was too short for diffusion-control based IMC growth.

Effects of Insert Metal Type on Interfacial Microstructure During Dissimilar Joining of TiAl Alloy to SCM440 by Friction Welding

Science.gov (United States)

Park, Jong-Moon; Kim, Ki-Young; Kim, Kyoung-Kyun; Ito, Kazuhiro; Takahashi, Makoto; Oh, Myung-Hoon

2018-03-01

Although the welding zone of direct bonding between a TiAl alloy and SCM440 can be obtained by friction welding, martensitic transformation and the formation of intermetallic compounds (IMCs) and cracks result in a lower tensile strength of the joints relative to those of other welding techniques. Insert metals were used as a buffer layer to relieve stress while increasing the bond strength. In this study, the microstructure and mechanical properties on welded joints of a TiAl alloy and SCM440 with various insert metals, were investigated. The TiAl/Cu/SCM440 and TiAl/Ni/SCM440 joints were fabricated using a servo-motor-type friction welding machine. As a result, it was confirmed that the formation of a welding flash was dependent on the insert metal type, and the strength of the base metal. At the TiAl/Cu/SCM440 interface, the formation of IMCs CuTiAl and Cu2TiAl was observed at TiAl/Cu, while no IMC formation was observed at Cu/SCM440. On the other hand, at the TiAl/Ni/SCM440 interface, several IMCs with more than 100 μm thickness were found, and roughly two compositions, viz., Ti2NiAl3 and TiNi2Al, were observed at the TiAl/Ni interface. At the Ni/SCM440 interface, 10 μm-thick FeNi and others were found.

Effects of Insert Metal Type on Interfacial Microstructure During Dissimilar Joining of TiAl Alloy to SCM440 by Friction Welding

Science.gov (United States)

Park, Jong-Moon; Kim, Ki-Young; Kim, Kyoung-Kyun; Ito, Kazuhiro; Takahashi, Makoto; Oh, Myung-Hoon

2018-05-01

Although the welding zone of direct bonding between a TiAl alloy and SCM440 can be obtained by friction welding, martensitic transformation and the formation of intermetallic compounds (IMCs) and cracks result in a lower tensile strength of the joints relative to those of other welding techniques. Insert metals were used as a buffer layer to relieve stress while increasing the bond strength. In this study, the microstructure and mechanical properties on welded joints of a TiAl alloy and SCM440 with various insert metals, were investigated. The TiAl/Cu/SCM440 and TiAl/Ni/SCM440 joints were fabricated using a servo-motor-type friction welding machine. As a result, it was confirmed that the formation of a welding flash was dependent on the insert metal type, and the strength of the base metal. At the TiAl/Cu/SCM440 interface, the formation of IMCs CuTiAl and Cu2TiAl was observed at TiAl/Cu, while no IMC formation was observed at Cu/SCM440. On the other hand, at the TiAl/Ni/SCM440 interface, several IMCs with more than 100 μm thickness were found, and roughly two compositions, viz., Ti2NiAl3 and TiNi2Al, were observed at the TiAl/Ni interface. At the Ni/SCM440 interface, 10 μm-thick FeNi and others were found.

Effect of process parameters on mechanical properties of friction stir spot welded magnesium to aluminum alloys

International Nuclear Information System (INIS)

Rao, H.M.; Yuan, W.; Badarinarayan, H.

2015-01-01

Highlights: • Lap-shear failure load of ∼2.5 kN was achieved in dissimilar Mg to Al spot welds. • Failure load depends on both welding geometrical features and IMCs formation. • Thin and discontinuous IMCs formed in stir zone are beneficial for weld strength. • Low heat input and good material mixing/interlocking is essential for high strength. - Abstract: Friction stir spot welding was applied to dissimilar cast magnesium (Mg) alloy AM60B and wrought aluminum (Al) alloy 6022-T4 under various welding conditions. The influence of tool rotation rate and shoulder plunge depth on lap-shear failure load was examined. Welds were made at four different tool rotation rates of 1000, 1500, 2000 and 2500 revolution per minute (rpm) and various tool shoulder plunge depths from 0 mm to 0.9 mm. The cross section of each weld exhibited the formation of intermetallic compounds (IMCs) in the stir zone. An increase in tool rotation rate decreased the width of the stir zone and resulted in lower lap-shear failure loads. The stir zone width increased and interlocking of IMCs was observed with an increase in tool shoulder plunge depth at 1000 rpm. High lap-shear failure loads were achieved in welds having a large stir zone width with formation of discontinuous IMCs at the tip of the interfacial hook. An average lap-shear failure load of 2.5 kN was achieved for welds made at 1000 rpm and 0.9 mm shoulder plunge. The present study suggests that the mechanical properties of friction stir spot welded dissimilar alloys are greatly influenced by the stir zone width, interfacial hooks and IMCs which are all weld process dependent

The possibility to use TiAl intermetallics for high temperature applications

International Nuclear Information System (INIS)

Molotkov, A.V.

1993-01-01

Titanium aluminide TiAl is the promising heat resisting structural material with operation temperature up to 850-900 deg C. This intermetallic compound is characterized by low density and high specific values of elasticity moduli and heat resistance properties in wide temperature range, as compared to known heat resisting titanium, iron and nickel base alloys. Test batch of pressed blades was manufactured of TiAl with the use of powder technology. Results of testing showed, that endurance strength of blades exceeded by 30% the strength, required for operation. The calculations showed, that the use of such blades in gas-turbine cagines could provide 30-40% decrease of mass of compressor blading

Obtaining and characterizing the binary compound Zr3Pt

International Nuclear Information System (INIS)

Tanoni, Diego; Arico, Sergio F; Alonso, Paula R

2006-01-01

The equilibrium phases in the Zr - Pt binary system are not fully defined. Experiences carried out from 0% to 50% at. Pt in the equilibrium diagram of Zr-Pt phases in 2001 revealed the presence of the intermetallic compounds Zr 2 Pt, Zr 5 Pt 3 , ZrPt (already previously identified by other authors) and a compound of 25% composition at Pt with an unidentified crystalline structure. This experimental work aims to fill out the information on this compound by characterizing its crystallography. An alloy was produced in the binary system Zr-Pt with a composition close to the stoichiometry by casting in an arc furnace, and was studied by optic and electronic metallography. The identification and crystallographic characterization of the phase is based on measurements of composition in electronic microwave and on analysis of spectrums obtained by X-ray diffraction. The results are presented, showing the presence in the cast structure of the solid solution zircon phases (hexagonal) and of the inter-metallic compound Zr 5 Pt 3 . These two phases were identified in the X-ray diffraction diagrams as well as the presence of other reflections that are associated with the inter-metallic Zr 3 Pt. The measurements of composition consistently reveal the presence of a phase of 25%at Pt composition. The structure's morphology shown in metallographies reveals the occurrence of a eutectic type transformation during cooling. We conclude that the formation of the phase sought in a composition 25 % at Pt should occur at temperatures below the eutectic transformation, and could be a peritectoid formation as was previously proposed. Therefore, the sample needs to be homogenized with thermal treatments that favor the formation and stabilization of the compound (CW)

Growth of intermetallics between Sn/Ni/Cu, Sn/Ag/Cu and Sn/Cu layered structures

International Nuclear Information System (INIS)

Horváth, Barbara; Illés, Balázs; Shinohara, Tadashi

2014-01-01

Intermetallic growth mechanisms and rates are investigated in Sn/Ni/Cu, Sn/Ag/Cu and Sn/Cu layer systems. An 8–10 μm thick Sn surface finish layer was electroplated onto a Cu substrate with a 1.5–2 μm thick Ni or Ag barrier layer. In order to induce intermetallic layer growth, the samples were aged in elevated temperatures: 50 °C and 125 °C. Intermetallic layer growth was checked by focused ion beam–scanning ion microscope. The microstructures and chemical compositions of the intermetallic layers were observed with a transmission electron microscope. It has been found that Ni barrier layers can effectively block the development of Cu 6 Sn 5 intermetallics. The intermetallic growth characteristics in the Sn/Cu and Sn/Ni/Cu systems are very similar. The intermetallic layer grows towards the Sn layer and forms a discrete layer. Differences were observed only in the growth gradients and surface roughness of the intermetallic layer which may explain the different tin whiskering properties. It was observed that the intermetallic layer growth mechanisms are completely different in the Ag barrier layers compared to the Ni layers. In the case of Sn/Ag/Cu systems, the Sn and Cu diffused through the Ag layer, formed Cu 6 Sn 5 intermetallics mainly at the Sn/Ag interface and consumed the Ag barrier layer. - Highlights: • Intermetallic growth was characterised in Sn/Ni/Cu, Sn/Ag/Cu and Sn/Cu layer systems. • Intermetallic growth rates and roughness are similar in the Sn/Cu and Sn/Ni/Cu systems. • Sn/Ni/Cu system contains the following intermetallic layer structure Sn–Ni3Sn4–Ni3Sn2–Ni3Sn–Ni. • In the case of Sn/Ag/Cu systems the Sn and Cu diffusion consumes the Ag barrier layer. • When Cu reaches the Sn/Ag interface a large amount of Cu 6 Sn 5 forms above the Ag layer

Superplastic ceramics and intermetallics and their potential applications

International Nuclear Information System (INIS)

Wadsworth, J.; Nieh, T.G.

1994-11-01

Recent advances in the basic understanding of superplasticity and superplastic forming of ceramics and intermetallics are reviewed. Fine-grained superplastic ceramics, including yttria-stabilized tetragonal zirconia polycrystal, Y- or MgO-doped Al 2 O 3 Hydroxyapatite, β-spodumene glass ceramics, Al 2 0 3 -YTZP two-phase composites, SiC-Si 3 N 4 and Fe-Fe 3 C composites, are discussed. Superplasticity in the nickel-base (e.g., Ni 3 Al and Ni 3 Si) and titanium-base intermetallics (TiAl and T1 3 Al), is described. Deformation mechanisms as well as microstructural requirements and effects such as grain size, grain growth, and grain-boundary phases, on the superplastic deformation behavior am addressed. Factors that control the superplastic tensile elongation of ceramics are discussed. Superplastic forming, and particularly biaxial gas-pressure forming, of several ceramics and intermetallics are presented with comments on the likelihood of commercial application

Friction stir welding joint of dissimilar materials between AZ31B magnesium and 6061 aluminum alloys: Microstructure studies and mechanical characterizations

Energy Technology Data Exchange (ETDEWEB)

Mohammadi, J. [Department of Materials Science and Engineering, Science and Research Branch, Islamic Azad University, Tehran 141554933 (Iran, Islamic Republic of); Behnamian, Y. [Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta T6G 2V4 (Canada); Mostafaei, A., E-mail: amir.mostafaei@gmail.com [Young Researchers and Elites Club, Tehran North Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Izadi, H. [Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta T6G 2V4 (Canada); Saeid, T. [Faculty of Materials Engineering, Sahand University of Technology, Tabriz 513351996 (Iran, Islamic Republic of); Kokabi, A.H. [Department of Materials Science and Engineering, Sharif University of Technology, Tehran 113659466 (Iran, Islamic Republic of); Gerlich, A.P., E-mail: adrian.gerlich@uwaterloo.ca [Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada)

2015-03-15

Friction stir welding is an efficient manufacturing method for joining dissimilar alloys, which can dramatically reduce grain sizes and offer high mechanical joint efficiency. Lap FSW joints between dissimilar AZ31B and Al 6061 alloy sheets were made at various tool rotation and travel speeds. Rotation and travel speeds varied between 560–1400 r/min and 16–40 mm/min respectively, where the ratio between these parameters was such that nearly constant pitch distances were applied during welding. X-ray diffraction pattern (XRD), optical microscopy images (OM), electron probe microanalysis (EPMA) and scanning electron microscopy equipped with an energy-dispersive X-ray spectroscopy (SEM-EDS) were used to investigate the microstructures of the joints welded. Intermetallic phases including Al{sub 12}Mg{sub 17} (γ) and Al{sub 3}Mg{sub 2} (β) were detected in the weld zone (WZ). For different tool rotation speeds, the morphology of the microstructure in the stir zone changed significantly with travel speed. Lap shear tensile test results indicated that by simultaneously increasing the tool rotation and travel speeds to 1400 r/min and 40 mm/min, the joint tensile strength and ductility reached a maximum. Microhardness measurements and tensile stress–strain curves indicated that mechanical properties were affected by FSW parameters and mainly depended on the formation of intermetallic compounds in the weld zone. In addition, a debonding failure mode in the Al/Mg dissimilar weld nugget was investigated by SEM and surface fracture studies indicated that the presence of intermetallic compounds in the weld zone controlled the failure mode. XRD analysis of the fracture surface indicated the presence of brittle intermetallic compounds including Al{sub 12}Mg{sub 17} (γ) and Al{sub 3}Mg{sub 2} (β). - Highlights: • Dissimilar Al/Mg joint was obtained by lap friction stir welding technique. • Effect of rotation and travel speeds on the formation of intermetallic

Friction stir welding joint of dissimilar materials between AZ31B magnesium and 6061 aluminum alloys: Microstructure studies and mechanical characterizations

International Nuclear Information System (INIS)

Mohammadi, J.; Behnamian, Y.; Mostafaei, A.; Izadi, H.; Saeid, T.; Kokabi, A.H.; Gerlich, A.P.

2015-01-01

Friction stir welding is an efficient manufacturing method for joining dissimilar alloys, which can dramatically reduce grain sizes and offer high mechanical joint efficiency. Lap FSW joints between dissimilar AZ31B and Al 6061 alloy sheets were made at various tool rotation and travel speeds. Rotation and travel speeds varied between 560–1400 r/min and 16–40 mm/min respectively, where the ratio between these parameters was such that nearly constant pitch distances were applied during welding. X-ray diffraction pattern (XRD), optical microscopy images (OM), electron probe microanalysis (EPMA) and scanning electron microscopy equipped with an energy-dispersive X-ray spectroscopy (SEM-EDS) were used to investigate the microstructures of the joints welded. Intermetallic phases including Al 12 Mg 17 (γ) and Al 3 Mg 2 (β) were detected in the weld zone (WZ). For different tool rotation speeds, the morphology of the microstructure in the stir zone changed significantly with travel speed. Lap shear tensile test results indicated that by simultaneously increasing the tool rotation and travel speeds to 1400 r/min and 40 mm/min, the joint tensile strength and ductility reached a maximum. Microhardness measurements and tensile stress–strain curves indicated that mechanical properties were affected by FSW parameters and mainly depended on the formation of intermetallic compounds in the weld zone. In addition, a debonding failure mode in the Al/Mg dissimilar weld nugget was investigated by SEM and surface fracture studies indicated that the presence of intermetallic compounds in the weld zone controlled the failure mode. XRD analysis of the fracture surface indicated the presence of brittle intermetallic compounds including Al 12 Mg 17 (γ) and Al 3 Mg 2 (β). - Highlights: • Dissimilar Al/Mg joint was obtained by lap friction stir welding technique. • Effect of rotation and travel speeds on the formation of intermetallic compounds • Microstructure and chemical

The Application of CPA to Calculations of the Mean Magnetic Moment in the Gd1-xNi, Gd1-xFe, Gd1xCox, and Y1-xCox Intermetallic Compounds

DEFF Research Database (Denmark)

Szpunar, B.; Kozarzewski, B.

1977-01-01

with a narrow d-band is considered. The magnetic moment of the alloy at zero temperature is calculated within the molecular field and Hartree-Fock approximations. Disorder is treated in the coherent potential approximation. Results are in good agreement with the experimental data obtained for the crystalline......Calculations are made of the mean magnetic moment per atom of the transition metal and the rare-earth metal in the intermetallic compounds, Gd1-x,Nix, Gd1-x Fex, Gd1-x Cox, and Y1-x Cox. A simple model of the disordered alloy consisting of spins localized on the rare-earth atoms and interacting...

Irregular Homogeneity Domains in Ternary Intermetallic Systems

Directory of Open Access Journals (Sweden)

Jean-Marc Joubert

2015-12-01

Full Text Available Ternary intermetallic A–B–C systems sometimes have unexpected behaviors. The present paper examines situations in which there is a tendency to simultaneously form the compounds ABx, ACx and BCx with the same crystal structure. This causes irregular shapes of the phase homogeneity domains and, from a structural point of view, a complete reversal of site occupancies for the B atom when crossing the homogeneity domain. This work reviews previous studies done in the systems Fe–Nb–Zr, Hf–Mo–Re, Hf–Re–W, Mo–Re–Zr, Re–W–Zr, Cr–Mn–Si, Cr–Mo–Re, and Mo–Ni–Re, and involving the topologically close-packed Laves, χ and σ phases. These systems have been studied using ternary isothermal section determination, DFT calculations, site occupancy measurement using joint X-ray, and neutron diffraction Rietveld refinement. Conclusions are drawn concerning this phenomenon. The paper also reports new experimental or calculated data on Co–Cr–Re and Fe–Nb–Zr systems.

Magnetic behavior of binary intermetallic compound YPd{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Pandey, Abhishek [S. N. Bose National Centre for Basic Sciences, Block-JD, Sector-III, Salt Lake, Kolkata 700098 (India); Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064 (India); Mazumdar, Chandan [Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064 (India)], E-mail: chandan.mazumdar@saha.ac.in; Ranganathan, R. [Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064 (India)

2009-05-12

We report the results of detailed magnetic studies on binary rare-earth-transition metal compound YPd{sub 3}. The results of temperature and magnetic field dependent DC-magnetic measurements along with the results of powder X-ray diffraction measurement and electrical transport have been discussed. The X-ray data suggest a well-defined ordered crystal lattice, free from any detectable impurity phase. Magnetization data exhibits predominant diamagnetic character at higher fields. However, the compound exhibits anomalous behavior at low fields.

Magnetic properties of the LaCu5-xCox compounds

International Nuclear Information System (INIS)

Crisan, V.; Popescu, V.; Vernes, A.; Andreica, D.; Cristea, S.; Koepe, B.

1996-01-01

Magnetic moments and Curie temperatures of the intermetallic compounds LaCu 5-x Co x (x = 5) are calculated using a recursion method in the framework of the spin-fluctuation theory of Mohn and Wohlfarth. (orig.)

Preparation and characterization of the Li(17)Pb(83) eutectic alloy and the LiPb intermetallic compound

International Nuclear Information System (INIS)

Jauch, U.; Karcher, V.; Schulz, B.

1986-01-01

Li(17)Pb(83) and LiPb were prepared from the pure elements in amounts of several hundred grams. The resolidified samples were characterized by melting points (eutectic temperature), chemical analysis and metallography. Using differential thermal analysis the heats of fusion were determined and the behaviour of the intermetallic phase LiPb in vacuum and high purified He was studied. The results from these investigations were applied to characterize Li(17)Pb(83) prepared in high amounts for technical application as a potential liquid breeder material. (orig.)

Development of Pb-Free Nanocomposite Solder Alloys

Directory of Open Access Journals (Sweden)

Animesh K. Basak

2018-04-01

Full Text Available As an alternative to conventional Pb-containing solder material, Sn–Ag–Cu (SAC based alloys are at the forefront despite limitations associated with relatively poor strength and coarsening of grains/intermetallic compounds (IMCs during aging/reflow. Accordingly, this study examines the improvement of properties of SAC alloys by incorporating nanoparticles in it. Two different types of nanoparticles were added in monolithic SAC alloy: (1 Al2O3 or (2 Fe and their effect on microstructure and thermal properties were investigated. Addition of Fe nanoparticles leads to the formation of FeSn2 IMCs alongside Ag3Sn and Cu6Sn5 from monolithic SAC alloy. Addition of Al2O3 nano-particles do not contribute to phase formation, however, remains dispersed along primary β-Sn grain boundaries and act as a grain refiner. As the addition of either Fe or Al2O3 nano-particles do not make any significant effect on thermal behavior, these reinforced nanocomposites are foreseen to provide better mechanical characteristics with respect to conventional monolithic SAC solder alloys.

Industrial hygiene survey. IMC, Agricultural Operation Division, Bartow, Florida

International Nuclear Information System (INIS)

Stephenson, F.; Cassady, M.

1977-10-01

An industrial hygiene survey was conducted at the Agricultural Operations Division, IMC, Bartow, Florida, on July 19-22, 1976, as part of the industry-wide study of the phosphate fertilizer industry. The phosphate ore mining operations, the plant, and the medical, safety, and industrial hygiene programs are described. The beneficiation plant was surveyed to determine the 8-hour time weighted averages of cadmium, chromium, vanadium, fluoride, arsenic, and silica. General area samples were taken for uranium and alpha-radiation. With the exception of uranium in the grinding area, all other elements analyzed came within the OSHA standards. However, several results exceed the NIOSH recommended standard

Magnetic propertiesof Lu.sub.2./sub.Fe.sub.16./sub.X (X = Fe, Ni, Cr, Si) intermetallics under high hydrostatic pressure

Czech Academy of Sciences Publication Activity Database

Kamarád, Jiří; Andreev, Alexander V.; Machátová, Zuzana; Arnold, Zdeněk

408-412, - (2006), s. 151-154 ISSN 0925-8388 R&D Projects: GA ČR(CZ) GA202/02/0739; GA MŠk(CZ) ME 495 Institutional research plan: CEZ:AV0Z10100521 Keywords : intermetallic compounds * Lu 2 Fe 17 * magnetic properties * high pressure Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.250, year: 2006

Establishment path and management innovation of mutually beneficial nonprofit organization (MBNPO: A study based on integrated marketing communications (IMC theory

Directory of Open Access Journals (Sweden)

Kwang-yong Shin

2017-05-01

Full Text Available Purpose - Research about the modern mutually beneficial nonprofit organizations (MBNPOs has great value because of the increasingly important role that the MBNPO plays in society. The establishment and management of MBNPOs are critical for its development. Design/methodology/approach - Integrated marketing communications (IMC theory is applied to the research on establishment and management innovation. The establishment of MBNPOs needs four sequential steps: identifying the target group, providing services to meet the demand of stakeholders, designing appropriate communication tactics and deploying proper organizational structure to accomplish efficient communication. Findings - Three types of approach enable traditional enterprises to transform into MBNPOs: product innovation, operational innovation and synergetic development. The application of IMC theory accomplishes management innovation of MBNPOs in three aspects: leading market-orientation specific to stakeholder-orientation, making management innovation systematic in MBNPOs and clarifying targets of management innovation in MBNPOs. Originality/value - This is one of the first examinations of establishment path and management innovation of MBNPO based on IMC theory.

Morphology of intermetallic phases in Al-Si cast alloys and their fracture behaviour

Directory of Open Access Journals (Sweden)

Lenka Hurtalová

2015-03-01

Full Text Available Applications of Al-Si cast alloys in recent years have increased especially in the automotive industry (dynamic exposed cast, en-gine parts, cylinder heads, pistons and so on. Controlling the microstructure of secondary aluminium cast alloys is very important, because these alloys contain more additional elements that form various intermetallic phases in the structure. Therefore, the contribution is dealing with the valuation type of intermetallic phases and their identification with using optical and scanning microscopy. Some of the intermetallic phases could be identified on the basis of morphology but some of them must be identified according EDX analysis. The properties of alu-minium alloy are affected by morphology of intermetallic phases and therefore it is necessary to study morphology and its fracture behav-iour. The present work shows morphology and typical fracture behaviour as the most common intermetallic phases forming in Al-Si alloys.

The effect of boron additions on irradiation-induced order changes in Ni3Al intermetallic compounds

International Nuclear Information System (INIS)

Njah, N.; Gilbon, D.; Dimitrov, O.

1995-01-01

The effects of boron additions (0.1 wt%) on the kinetics of atomic order changes in a Ni 76 Al 24 intermetallic compound, under 1 MeV electron irradiation, were investigated at temperatures of 293 K and 410 K and displacement rates of 0.09 x 10 -3 to 4.7 x 10 -3 dpa.s -1 . In these irradiation conditions, a state of residual order was obtained for long irradiation times, characterized by a steady state order parameter S∞; it corresponds to a competition between two opposite features: irradiation disordering and thermal reordering enhanced by irradiation. Boron additions did not affect the efficiency of irradiation-induced disordering: the disordering cross-section (or, equivalently, the number of replacements per displacement var-epsilon) were comparable with and without a boron addition. By contrast, the S∞ values at 293 K were much lower in the alloy containing boron. Since boron does not change the disordering rate, the large difference between the values obtained in undoped and in boron-doped alloys shows that the reordering rate is strongly reduced by the presence of boron. Thus, boron modifies the mobility of the defects responsible for the irradiation-enhanced diffusion. The data on dislocation-loop size and the reordering kinetics suggest that vacancies are trapped by boron at low temperatures and immobilized, probably by the formation of a boron-vacancy complex. The effect becomes weaker at higher displacement rates and higher temperatures, probably due to the boron-vacancy complexes becoming unstable. It is proposed that two different reordering mechanisms may be operative at 293 K, according to the presence of boron: reordering is promoted by vacancy migration in the Ni 76 Al 24 alloy, whereas in the Ni 76 Al 24 (0.1 wt%B) alloy, it is promoted by the migration of split-interstitials or/and of low-mobility vacancy-boron complexes

Influence of the volume-contact area ratio on the growth behavior of the Cu-Sn intermetallic phase

Science.gov (United States)

Giddaluri, Venkatakamakshi Supraja

Solder Joints play a very important role in electronic packaging industry by serving as mechanical support and provides integrity to the device. The increasing demand for high performance, environmental and economic feasibility and miniaturization led to the development of high density interconnects. With the reduction in the size/standoff height of the solder reliability issues in the surface mount assemblies and packaging structures under various rigorous environments are becoming significant. One of the most important impact factors that affect the solder joint reliability is the growth rate IMC formed between the solder and substrate with reduction in joint size. IMC formation is required to ensure good bonding and connectivity of the device in packaging. However excess IMC growth rate is detrimental to the device from mechanical aspects due to its brittle nature. Thus there is a need to study effect the IMC growth rate behavior with the solder joint size/standoff height. In this present study, two solder joints of different standoff heights and same composition (pure Sn solder) are used subjected to reflow process at 270°C for 1--7 min to study solid liquid interfacial reaction on joint size and the same experiment is repeated with SAC alloy of composition (96.5% Sn, 3.0% Ag, 0.5% Cu) to investigate the effect of joint size and initial copper concentration on IMC growth rate. The IMC thickness of the Sn 15microm solder joint at 1 min and 7 min is found to be 1.52microm and 2.86microm respectively while that of Sn 150microm solder joint is 1.31microm and 3.16 microm. The thickness is high in low standoff height sample at the early stage of reaction with decrease in IMC growth rate as the time of reflow increases. In case of 25microm SAC alloy solder joint the IMC thickness from 1 and 7 min is found to be 2.1microm and 3.5microm while that of 250microm SAC alloy solder joint its 1.43microm and3.235microm. Similar trend is observed but the IMC thickness is more

Spark plasma sintering of titanium aluminide intermetallics and its composites

Science.gov (United States)

Aldoshan, Abdelhakim Ahmed

Titanium aluminide intermetallics are a distinct class of engineering materials having unique properties over conventional titanium alloys. gamma-TiAl compound possesses competitive physical and mechanical properties at elevated temperature applications compared to Ni-based superalloys. gamma-TiAl composite materials exhibit high melting point, low density, high strength and excellent corrosion resistance. Spark plasma sintering (SPS) is one of the powder metallurgy techniques where powder mixture undergoes simultaneous application of uniaxial pressure and pulsed direct current. Unlike other sintering techniques such as hot iso-static pressing and hot pressing, SPS compacts the materials in shorter time (< 10 min) with a lower temperature and leads to highly dense products. Reactive synthesis of titanium aluminide intermetallics is carried out using SPS. Reactive sintering takes place between liquid aluminum and solid titanium. In this work, reactive sintering through SPS was used to fabricate fully densified gamma-TiAl and titanium aluminide composites starting from elemental powders at different sintering temperatures. It was observed that sintering temperature played significant role in the densification of titanium aluminide composites. gamma-TiAl was the predominate phase at different temperatures. The effect of increasing sintering temperature on microhardness, microstructure, yield strength and wear behavior of titanium aluminide was studied. Addition of graphene nanoplatelets to titanium aluminide matrix resulted in change in microhardness. In Ti-Al-graphene composites, a noticeable decrease in coefficient of friction was observed due to the influence of self-lubrication caused by graphene.

The influence of the surface distribution of Al6(MnFe) intermetallic on the electrochemical response of AA5083 aluminium alloy in NaCl solutions

International Nuclear Information System (INIS)

Bethencourt, M.; Botana, F.J.; Calvino, J.J.; Perez, J.; Rodriguez, M.A.; Marcos, M.

1998-01-01

In this paper the behaviour against pitting corrosion of different samples of AA5083 aluminium alloy has been studied. A correlation between the microstructure of the samples and their susceptibility to pitting has been established. Metallographic analysis combined with SEM and EDS techniques have allowed us to detect three intermetallic compounds in the samples. The particle size distribution and surface density of each intermetallic phase have been evaluated for the three AA5083 alloy samples coming from different suppliers. Significant differences in the microstructure of the three samples have been found. Full immersion test carried out in 3.5% aerated aqueous solutions showed that pitting starts at the locations of the Al 6 (MnFe) intermetallic particles. As a consequence of this, the samples with higher Al 6 (MnFe) content showed a higher pit density on its surface. The results of cyclic polarisation tests showed also a good correlation with the microstructural parameters. (orig.)

Intermetallics structures, properties, and statistics

CERN Document Server

Steurer, Walter

2016-01-01

The focus of this book is clearly on the statistics, topology, and geometry of crystal structures and crystal structure types. This allows one to uncover important structural relationships and to illustrate the relative simplicity of most of the general structural building principles. It also allows one to show that a large variety of actual structures can be related to a rather small number of aristotypes. It is important that this book is readable and beneficial in the one way or another for everyone interested in intermetallic phases, from graduate students to experts in solid-state chemistry/physics/materials science. For that purpose it avoids using an enigmatic abstract terminology for the classification of structures. The focus on the statistical analysis of structures and structure types should be seen as an attempt to draw the background of the big picture of intermetallics, and to point to the white spots in it, which could be worthwhile exploring. This book was not planned as a textbook; rather, it...

Theory of Valence Transitions in Ytterbium and Europium Intermetallics

International Nuclear Information System (INIS)

Zlatic, V.; Freericks, J.K.

2001-01-01

The exact solution of the multi-component Falicov-Kimball model in infinite-dimensions is presented and used to discuss a new fixed point of valence fluctuating intermetallics with Yb and Eu ions. In these compounds, temperature, external magnetic field, pressure, or chemical pressure induce a transition between a metallic state with the f-ions in a mixed-valent (non-magnetic) configuration and a semi-metallic state with the f-ions in an integral-valence (paramagnetic) configuration. The zero-field transition occurs at the temperature T V , while the zero-temperature transition sets in at the critical field H c . We present the thermodynamic and dynamic properties of the model for an arbitrary concentration of d- and f -electrons. For large U, we find a MI transition, triggered by the temperature or field- induced change in the f-occupancy. (author)

Industrial hygiene survey. IMC, Phosphate Chemical Complex, New Wales, Florida

International Nuclear Information System (INIS)

Stephenson, F.; Cassady, M.

1977-10-01

An industrial hygiene survey was conducted by NIOSH at IMC Phosphate Chemical Complex, New Wales, Florida, on June 7-11, 1976, as part of a study of the phosphate industry. Phosphate fertilizer manufacturing, the plant, and the medical, safety, and industrial hygiene programs are described. During the study 8-hour time weighted averages were determined for exposure to arsenic, cadmium, chromium, vanadium, phosphoric acid, and sulfuric acid for workers involved in cleaning out phosphoric acid reactor vessels. General area samples were collected for fluorides, radon, and uranium. Several samples were above the NIOSH recommended levels for arsenic and chromium

Molecular dynamics simulations of radiation damage in D019 Ti3Al intermetallic compound

International Nuclear Information System (INIS)

Voskoboinikov, Roman E.

2013-01-01

Molecular dynamics (MD) has been applied to simulate the radiation damage created in displacement cascades in D0 19 Ti 3 Al structural intermetallics. Collision cascades formed by the recoil of either Al or Ti primary knock-on atoms (PKA) with energy E PKA = 5, 10, 15 or 20 keV were considered in Ti 3 Al single crystals at T = 100, 300, 600 and 900 K. At least 24 different cascades for each (E PKA , T, PKA type) set were simulated. A comprehensive treatment of the modelling results has been carried out. We have evaluated the number of Frenkel pairs, fraction of Al and Ti vacancies, self-interstitial atoms and anti-sites as a function of (E PKA ,T, PKA type). Preferred formation of both Al vacancies and self-interstitial atoms in D0 19 Ti 3 Al exposed to irradiation has been detected

Microstructure and electrode performance of AB5-type hydride-forming compounds

NARCIS (Netherlands)

Notten, P.H.L.

1998-01-01

A interesting experimental technique is proposed to investigate the hydrideformation/ decomposition reaction of intermetallic compounds. This X-ray diffraction (XRD) technique combines hydrogen absorptionldesorption measure ments with in situ XRD measurements. A high pressure XRD cell allows gas

Production of nanograined intermetallics using high-pressure torsion

Energy Technology Data Exchange (ETDEWEB)

Alhamidi, Ali; Edalati, Kaveh; Horita, Zenji, E-mail: horita@zaiko.kyushu-u.ac.jp [Department of Materials Science and Engineering, Faculty of Engineering, Kyushu University, Fukuoka (Japan)

2013-11-01

Formation of intermetallics is generally feasible at high temperatures when the lattice diffusion is fast enough to form the ordered phases. This study shows that nanograined intermetallics are formed at a low temperature as 573 K in Al- 25 mol% Ni, Al- 50 mol.% Ni and Al- 50 mol% Ti powder mixtures through powder consolidation using high-pressure torsion (HPT). For the three compositions, the hardness gradually increases with straining but saturates to the levels as high as 550-920 Hv. In addition to the high hardness, the TiAl material exhibits high yield strength as {approx}3 GPa with good ductility as {approx}23%, when they are examined by micropillar compression tests. X-ray diffraction analysis and high-resolution transmission electron microscopy reveal that the significant increase in hardness and strength is due to the formation of nanograined intermetallics such as Al{sub 3}Ni, Al{sub 3}Ni{sub 2}, TiAl{sub 3}, TiAl{sub 2} and TiAl with average grain sizes of 20-40 nm (author)

Antiferromagnetism, structural instability and frustration in intermetallic AFe4X2 systems

Science.gov (United States)

Rosner, Helge; Bergmann, Christoph; Weber, Katharina; Kraft, Inga; Mufti, N.; Klauss, Hans-Henning; Dellmann, T.; Woike, T.; Geibel, Christoph

2013-03-01

Magnetic systems with reduced dimensionality or frustration attract strong interest because these features lead to an increase of quantum fluctuations and often result in unusual properties. Here, we present a detailed study of the magnetic, thermodynamic, and structural properties of the intermetallic AFe4X2 compounds (A=Sc,Y,Lu,Zr; X=Si,Ge) crystallizing in the ZrFe4Si2 structure type. Our results evidence that these compounds cover the whole regime from frustrated AFM order up to an AFM quantum critical point. Susceptibility χ(T), specific heat, resistivity, and T-dependent XRD measurements were performed on polycrystalline samples. In all compounds we observed a Curie-Weiss behavior in χ(T) at high T indicating a paramagnetic moment of about 3μB/Fe. Magnetic and structural transitions as previously reported for YFe4Ge2 occur in all compounds with trivalent A. However, transition temperatures, nature of the transition as well as the relation between structural and magnetic transitions change significantly with the A element. Low TN's and large θCW /TN ratios confirm the relevance of frustration. The results are analyzed and discussed with respect to electronic, structural and magnetic instabilities applying DFT calculations. Financial support from the DFG (GRK 1621) is acknowledged

Electrochemical properties of the passive film on bulk Zr–Fe–Cr intermetallic fabricated by spark plasma sintering

Energy Technology Data Exchange (ETDEWEB)

Bai, Yakui [School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Ling, Yunhan, E-mail: yhling@mail.tsinghua.edu.cn [School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Lai, Wensheng [School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Xing, Shupei; Ma, Wen [School of Materials Science and Engineering, Inner Mongolia University of Technology, Huhhot 010051 (China)

2016-12-01

Highlights: • SPS was employed to prepare Zr-based intermetallics which were commonly existed in zircaloy. • Zr-based intermetallics act as cathode when they embedded in zirconium matrix. • The passive films on surface of intermetallics behaved as n-type semiconductors. • Carrier concentration of Zr(Fe{sub 3}Cr){sub 2} was much lower than that of other intermetallics. - Abstract: Although Zr-based second phase particles (SPPs) are important factors influencing corrosion resistance of zircaloy cladding materials, the corrosion behavior of SPPs has not been investigated by means of electrochemical method so far. In order to clarify the role of SPPs commonly existed in zircaloy, bulk Zr-based intermetallics were firstly fabricated by spark plasma sintering (SPS) at temperatures 1373 K and an applied pressure of 60 MPa in this work. Both the natural passive film on surface and oxidation behavior of intermetallic has been investigated in this work. X-ray diffraction (XRD) pattern showed that as-prepared intermetallic of crystal structure belongs to Laves phase with AB{sub 2} type. Electrochemical measurement of passive film on surface of bulk Zr-based intermetallic exhibited significant difference with that of zirconium. Potentiodynamic measurements results revealed that intermetallic exhibited higher corrosion potential and lower corrosion current density than that of pure zirconium, implying that Zr-based second phase will act as cathode when they are included in zirconium matrix. Meanwhile, significant improvement of Zr–Fe–Cr intermetallic on the water chemistry corrosion resistance was demonstrated comparing with Zr–Fe and Zr–Cr binary intermetallics.

Antiferromagnetic ordering of Er2NiSi3 compound

International Nuclear Information System (INIS)

Pakhira, Santanu; Mazumdar, Chandan; Ranganathan, R.

2014-01-01

Ternary intermetallics of the stoichiometric composition R 2 TX 3 , where, R = rare earth element, T = d-electron transition metal and X= p-electron element, crystallizes in hexagonal A1B 2 type crystal structure with space group P6/mmm. We report here the synthesis and basic magnetic properties of the compound Er 2 NiSi 3 . Paramagnetic to antiferromagnetic phase change occurs below 5.4 K for this compound. (author)

Atomic interaction of the MEAM type for the study of intermetallics in the Al–U alloy

International Nuclear Information System (INIS)

Pascuet, M.I.; Fernández, J.R.

2015-01-01

Interaction for both pure Al and Al–U alloys of the MEAM type are developed. The obtained Al interatomic potential assures its compatibility with the details of the framework presently adopted. The Al–U interaction fits various properties of the Al_2U, Al_3U and Al_4U intermetallics. The potential verifies the stability of the intermetallic structures in a temperature range compatible with that observed in the phase diagram, and also takes into account the greater stability of these structures relative to others that are competitive in energy. The intermetallics are characterized by calculating elastic and thermal properties and point defect parameters. Molecular dynamics simulations show a growth of the Al_3U intermetallic in the Al/U interface in agreement with experimental evidence. - Highlights: • Potential parameters for Al and Al–U systems are obtained. • Intermetallics are characterized by calculating elastic and thermal properties. • Point defect diffusivities are calculated for the three intermetallics. • Growth of the Al_3U intermetallic is shown to occur in the Al/U interface as in the real alloy.

On the nature of chromatic color of PdIn intermetallic compounds

International Nuclear Information System (INIS)

Nomerovannaya, L.V.; Kirillova, M.M.; Savitskij, E.M.; Polyakova, V.P.; Gorina, N.B.; Korenovskij, N.L.; AN SSSR, Moscow. Inst. Metallurgii)

1979-01-01

For the first time measured are the indexes of refraction and absorption of the six samples in the region of PdIn compound existence within the spectral range from 0.072 to 4.94 eV. The peculiarities of intersone light absoprtion are studied, the energy shift of absorption edge with the change of indium concentration is determined and the nature of the appearance of unusual colors of these compounds is explained. The refraction capacity for the normal light fall is calculated according to the values of refraction and absorption indexes. The refraction capacity curves for compounds with 42, 46, 50 at % indium content are presented, whose spectral dependence and high refraction (40-98%) show that PdIn compounds possess metallic conductivity

Crystallographic features of the martensitic transformation and their impact on variant organization in the intermetallic compound Ni50Mn38Sb12 studied by SEM/EBSD.

Science.gov (United States)

Zhang, Chunyang; Zhang, Yudong; Esling, Claude; Zhao, Xiang; Zuo, Liang

2017-09-01

The mechanical and magnetic properties of Ni-Mn-Sb intermetallic compounds are closely related to the martensitic transformation and martensite variant organization. However, studies of these issues are very limited. Thus, a thorough crystallographic investigation of the martensitic transformation orientation relationship (OR), the transformation deformation and their impact on the variant organization of an Ni 50 Mn 38 Sb 12 alloy using scanning electron microscopy/electron backscatter diffraction (SEM/EBSD) was conducted in this work. It is shown that the martensite variants are hierarchically organized into plates, each possessing four distinct twin-related variants, and the plates into plate colonies, each containing four distinct plates delimited by compatible and incompatible plate interfaces. Such a characteristic organization is produced by the martensitic transformation. It is revealed that the transformation obeys the Pitsch relation ({0[Formula: see text]} A // {2[Formula: see text]} M and 〈0[Formula: see text]1〉 A // 〈[Formula: see text]2〉 M ; the subscripts A and M refer to austenite and martensite, respectively). The type I twinning plane K 1 of the intra-plate variants and the compatible plate interface plane correspond to the respective orientation relationship planes {0[Formula: see text]} A and {0[Formula: see text]} A of austenite. The three {0[Formula: see text]} A planes possessed by each pair of compatible plates, one corresponding to the compatible plate interface and the other two to the variants in the two plates, are interrelated by 60° and belong to a single 〈11[Formula: see text]〉 A axis zone. The {0[Formula: see text]} A planes representing the two pairs of compatible plates in each plate colony belong to two 〈11[Formula: see text]〉 A axis zones having one {0[Formula: see text]} A plane in common. This common plane defines the compatible plate interfaces of the two pairs of plates. The transformation strains to form the

Research Article Special Issue

African Journals Online (AJOL)

pc

2017-11-24

Nov 24, 2017 ... STUDY BETWEEN INTERMETALLIC LAYER AND DROP TEST .... ore solder balls. Dropped lymer core solder ball. On. SAC solder ball. Figure 2. 144 hours. IMC layer for. AC solder ball from 24 to to AC stress test. .... International Conference on Electronic Devices, Systems and Applications, 2010, pp.

Surfaces of Intermetallics: Quasicrystals and Beyond

Energy Technology Data Exchange (ETDEWEB)

Yuen, Chad [Iowa State Univ., Ames, IA (United States)

2012-01-01

The goal of this work is to characterize surfaces of intermetallics, including quasicrystals. In this work, surface characterization is primarily focused on composition and structure using X-ray photoelectron spectroscopy (XPS) and scanning tunneling microscopy (STM) performed under ultrahigh vacuum (UHV) conditions.

Study on the Mechanical Properties and Corrosion Behaviors of Fe-(20, 45) wt%Gd Intermetallics

Energy Technology Data Exchange (ETDEWEB)

Kang, Bo Kyeong; Baik, Youl; Choi, Yong [Dankook University, Chungnam (Korea, Republic of); Moon, Byung Moon [Korea Institute of Industrial Technology, Incheon (Korea, Republic of)

2017-02-15

Fe-(20, 45 wt%) Gd intermetallics were vacuum arc melted as the mother alloy of a neutron shielding and absorbing material. The structure of the cast Fe-20 wt%Gd intermetallics had primary dendrites with a short width of about 2 μm, which became coarse with increasing Gd content. The final compositions of the Fe-20 wt%Gd and Fe-45 wt%Gd intermetallics determined by Rietveld refinement were mainly Fe{sub 3}Gd with 26.6 at%Fe{sub 2}Gd, and Fe{sub 3}Gd with various intermetallics like 13.9 at%Fe{sub 2}Gd, 7.3 at%Fe{sub 9}Gd and 3.9 at%Fe{sub 17}Gd{sub 2}, respectively. The micro-hardnesses, yield strength, ultimate compressive strength and elongation of the Fe-20 wt%Gd intermetallics were 629±12 Hv, 753 MPa, 785 MPa and 4%, respectively, and those of the Fe-45 wt%Gd intermetallics were 741±13 Hv, 772 MPa, 823 MPa and 3%. Passivity was not present in artificial sea water at room temperature. The corrosion potentials and the corrosion rates of the Fe-20 wt%Gd and Fe-45 wt%Gd intermetallics were –624 mV{sub SHE}, 2.771 mA/cm{sup 2} , and –804 mV{sub SHE}, 3.397 mA/cm{sup 2} , respectively. The corroded surface of the Fe-Gd intermetallics contained corrosion products like gadolinium with iron, which detached to leave a trail of pits.

Atomic interaction of the MEAM type for the study of intermetallics in the Al–U alloy

Energy Technology Data Exchange (ETDEWEB)

Pascuet, M.I. [CONICET, Avda. Rivadavia 1917, 1033 Buenos Aires (Argentina); Fernández, J.R., E-mail: julrfern@cnea.gov.ar [CONICET, Avda. Rivadavia 1917, 1033 Buenos Aires (Argentina); CAC-CNEA, Avda. Gral Paz 1499, 1650 Buenos Aires (Argentina); UNSAM, Avda. Gral Paz 1499, 1650 Buenos Aires (Argentina)

2015-12-15

Interaction for both pure Al and Al–U alloys of the MEAM type are developed. The obtained Al interatomic potential assures its compatibility with the details of the framework presently adopted. The Al–U interaction fits various properties of the Al{sub 2}U, Al{sub 3}U and Al{sub 4}U intermetallics. The potential verifies the stability of the intermetallic structures in a temperature range compatible with that observed in the phase diagram, and also takes into account the greater stability of these structures relative to others that are competitive in energy. The intermetallics are characterized by calculating elastic and thermal properties and point defect parameters. Molecular dynamics simulations show a growth of the Al{sub 3}U intermetallic in the Al/U interface in agreement with experimental evidence. - Highlights: • Potential parameters for Al and Al–U systems are obtained. • Intermetallics are characterized by calculating elastic and thermal properties. • Point defect diffusivities are calculated for the three intermetallics. • Growth of the Al{sub 3}U intermetallic is shown to occur in the Al/U interface as in the real alloy.

A survey of combustible metals, thermites, and intermetallics for pyrotechnic applications

Energy Technology Data Exchange (ETDEWEB)

Fischer, S.H.; Grubelich, M.C.

1996-08-01

Thermite mixtures, intermetallic reactants, and metal fuels have long been used in pyrotechnics. Advantages include high energy density, impact insensitivity, high combustion temperature, and a wide range of gas production. They generally exhibit high temperature stability and possess insensitive ignition properties. This paper reviews the applications, benefits, and characteristics of thermite mixtures, intermetallic reactants, and metal fuels. 50 refs, tables.

First principle studies of electronic and magnetic properties of Lanthanide-Gold (RAu) binary intermetallics

Energy Technology Data Exchange (ETDEWEB)

Ahmad, Sardar [Center for Computational Materials Science, University of Malakand, Chakdara, 18800 Pakistan (Pakistan); Department of Chemistry, University of Malakand, Chakdara, 18800 Pakistan (Pakistan); Ahmad, Rashid, E-mail: rashmad@gmail.com [Center for Computational Materials Science, University of Malakand, Chakdara, 18800 Pakistan (Pakistan); Department of Chemistry, University of Malakand, Chakdara, 18800 Pakistan (Pakistan); Jalali-Asadabadi, S. [Department of Physics, Faculty of Sciences, University of Isfahan (UI), Hezar Gerib Avenue, Isfahan 81746-73441 (Iran, Islamic Republic of); Ali, Zahid [Center for Computational Materials Science, University of Malakand, Chakdara, 18800 Pakistan (Pakistan); Department of Physics, University of Malakand, Chakdara, 18800 Pakistan (Pakistan); Ahmad, Iftikhar [Center for Computational Materials Science, University of Malakand, Chakdara, 18800 Pakistan (Pakistan); Vice Chancellor, Abbott Abad University of Science and Technology, Abbott Abad (Pakistan)

2017-01-15

In this article we explore the electronic and magnetic properties of RAu intermetallics (R=Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu) for the first time. These properties are calculated by using GGA, GGA+U and hybrid density functional theory (HF) approaches. Our calculations show that HF provides superior results, consistent to the experimentally reported data. The chemical bonding between rare-earth and gold atoms within these compounds are explained on the basis of spin dependent electronic clouds in different planes, which shows predominantly ionic and metallic nature between Au and R atoms. The Cohesive energies of RAu compounds show direct relation with the melting points. Spin-dependent electronic band structure demonstrates that all these compounds are metallic in nature. The magnetic studies show that HoAu and LuAu are stable in non-magnetic structure, PrAu is stable in ferromagnetic phase and CeAu, NdAu, SmAu, GdAu, TbAu, DyAu, ErAu, TmAu, YbAu are anti-ferromagnetic materials.

Electronic structure, elasticity, bonding features and mechanical behaviour of zinc intermetallics: A DFT study

Energy Technology Data Exchange (ETDEWEB)

Fatima, Bushra, E-mail: bushrafatima25@gmail.com; Acharya, Nikita; Sanyal, Sankar P. [Department of Physics, Barkatullah University, Bhopal, 462026 (India)

2016-05-06

The structural stability, electronic structure, elastic and mechanical properties of TiZn and ZrZn intermetallics have been studied using ab-initio full potential linearized augmented plane wave (FP-LAPW) method within generalized gradient approximation for exchange and correlation potentials. The various structural parameters, such as lattice constant (a{sub 0}), bulk modulus (B), and its pressure derivative (B’) are analysed and compared. The investigation of elastic constants affirm that both TiZn and ZrZn are elastically stable in CsCl (B{sub 2} phase) structure. The electronic structures have been analysed quantitatively from the band structure which reveals the metallic nature of these compounds. To better illustrate the nature of bonding and charge transfer, we have also studied the Fermi surfaces. The three well known criterion of ductility namely Pugh’s rule, Cauchy’s pressure and Frantsevich rule elucidate the ductile nature of these compounds.

Tracing crystal-field splittings in the rare-earth-based intermetallic CeIrIn5

Science.gov (United States)

Chen, Q. Y.; Wen, C. H. P.; Yao, Q.; Huang, K.; Ding, Z. F.; Shu, L.; Niu, X. H.; Zhang, Y.; Lai, X. C.; Huang, Y. B.; Zhang, G. B.; Kirchner, S.; Feng, D. L.

2018-02-01

Crystal electric field states in rare earth intermetallics show an intricate entanglement with the many-body physics that occurs in these systems and that is known to lead to a plethora of electronic phases. Here we attempt to trace different contributions to the crystal electric field (CEF) splittings in CeIrIn5, a heavy-fermion compound and member of the Ce M In5 (M = Co, Rh, Ir) family. To this end, we utilize high-resolution resonant angle-resolved photoemission spectroscopy (ARPES) and present a spectroscopic study of the electronic structure of this unconventional superconductor over a wide temperature range. As a result, we show how ARPES can be used in combination with thermodynamic measurements or neutron scattering to disentangle different contributions to the CEF splitting in rare earth intermetallics. We also find that the hybridization is stronger in CeIrIn5 than CeCoIn5 and the effects of the hybridization on the Fermi volume increase is much smaller than predicted. By providing experimental evidence for 4 f7/2 1 splittings which, in CeIrIn5, split the octet into four doublets, we clearly demonstrate the many-body origin of the so-called 4 f7/2 1 state.

FP-LAPW study of structural, electronic, elastic, mechanical and thermal properties of AlFe intermetallic

Energy Technology Data Exchange (ETDEWEB)

Jain, Ekta, E-mail: jainekta05@gmail.com [Department of Physics, Government M. L. B. Girls P. G. Autonomous College, Bhopal-462002 (India); Pagare, Gitanjali, E-mail: gita-pagare@yahoo.co.in [Department of Physics, Sarojini Naidu Government Girls P. G. Autonomous College, Bhopal-462016 (India); Sanyal, S. P., E-mail: sps.physicsbu@gmail.com [Department of Physics, Barkatullah University, Bhopal-462026 (India)

2016-05-06

The structural, electronic, elastic, mechanical and thermal properties of AlFe intermetallic compound in B{sub 2}-type (CsCl) structure have been investigated using first-principles calculations. The exchange-correlation term was treated within generalized gradient approximation. Ground state properties i.e. lattice constants (a{sub 0}), bulk modulus (B) and first-order pressure derivative of bulk modulus (B’) are presented. The density of states are derived which show the metallic character of present compound. Our results for C{sub 11}, C{sub 12} and C{sub 44} agree well with previous theoretical data. Using Pugh’s criteria (B/G{sub H} < 1.75), brittle character of AlFe is satisfied. In addition shear modulus (G{sub H}), Young’s modulus (E), sound wave velocities and Debye temperature (θ{sub D}) have also been estimated.

The role of intermetallic precipitates in Ti-62222S

Energy Technology Data Exchange (ETDEWEB)

Evans, D J [US Air Force Mater. Directorate Wright Lab., Wright Patterson AFB, OH (United States); Broderick, T F [US Air Force Mater. Directorate Wright Lab., Wright Patterson AFB, OH (United States); Woodhouse, J B [UES Inc, Dayton, OH (United States); Hoenigman, J R [Wright State Univ., Dayton, OH (United States). Research Inst.

1996-08-15

Samples of Ti-62222-0.23wt.%Si were heat treated and aged at temperatures ranging from 1150 F to 1500 F with the view of effecting selective precipitation of {alpha}{sub 2} precipitates and silicides (i.e. Ti{sub x}Zr{sub 5-x}Si{sub 3}). The effect of these intermetallic precipitates on the mechanical properties and fracture morphology was assessed via three separate microstructural conditions: Ti-62222S with {alpha}{sub 2} precipitates, Ti-62222S with {alpha}{sub 2} and silicide precipitates, and Ti-62222S with silicide precipitates. Both types of intermetallic precipitate appear to lower the fracture toughness, however {alpha}{sub 2} promotes intergranular fracture while silicides lead to transgranular failure and dimpling. The combined presence of the {alpha}{sub 2} and silicides leads to mixed mode failure. Further, since {alpha}{sub 2} is present in the {alpha} phase and silicides precipitate out in the {beta} phase, it appears that the effect of each of these intermetallics in Ti-62222S is additive rather than synergistic. (orig.)

Effect of friction time on mechanical and metallurgical properties of continuous drive friction welded Ti6Al4V/SUS321 joints

International Nuclear Information System (INIS)

Li, Peng; Li, Jinglong; Salman, Muhammad; Liang, Li; Xiong, Jiangtao; Zhang, Fusheng

2014-01-01

Highlights: • The effect of friction time on the microstructure and joint strength was studied. • The fit of burn-off lengths at different times yields a simple equation. • The longer friction time leads to oversized flash in Ti6Al4V side and overgrown IMCs. • An IMZ with width less than 3 μm is beneficial to make a strong metallurgical bond. • The average strength of 560 MPa is obtained and higher than ever reported results. - Abstract: Dissimilar joint of Ti6Al4V titanium alloy and SUS321 stainless steel was fabricated by continuous drive friction welding. The effect of friction time on the mechanical properties was evaluated by hardness measurement and tensile test, while the interfacial microstructure and fracture morphologies were analyzed by scanning electron microscope, energy dispersive spectroscope and X-ray Diffraction. The results show that the tensile strength increases with friction time under the experimental conditions. And the maximum average strength 560 MPa, which is 90.3% of the SUS321 base metal, is achieved at a friction time of 4 s. For all samples, studied fracture occurred along the joint interface, where intermetallic compounds like FeTi, Fe 2 Ti, Ni 3 (Al, Ti) and Fe 3 Ti 3 O and many other phases were formed among elements from the two base metals. The width of intermetallic compounds zone increases with friction time up to 3 μm, below which it is beneficial to make a strong metallurgical bond. However, the longer friction time leads to oversized flash on the Ti6Al4V side and overgrown intermetallic compounds. Finally the optimized friction time was discussed to be in the range of 2–4 s, under which the sound joint with good reproducibility can be expected

Viscoelastic wormlike micelles formed by ionic liquid-type surfactant [C16imC8]Br towards template-assisted synthesis of CdS quantum dots.

Science.gov (United States)

Hu, Yimin; Han, Jie; Ge, Lingling; Guo, Rong

2018-01-31

In this paper, viscoelastic wormlike micelles consisting of cationic liquid-type surfactant, 1-hexadecyl-3-octyl imidazolium bromide ([C 16 imC 8 ]Br), water and different additives were utilized for the synthesis of CdS quantum dots. First, the influence of different additives, such as [Cd(NH 3 ) 6 ]Cl 2 and ethanethioamid (precursors for the synthesis of CdS quantum dots), and temperature on the viscoelasticity of the [C 16 imC 8 ]Br aqueous solution was studied by dynamic and steady rheology. Furthermore, the synthesized CdS quantum dots and their photoluminescence properties were characterized by transmission electron microscopy (TEM), UV-Vis absorption spectroscopy, X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDX). In the end, the mechanism for the synthesis of CdS quantum dots in [C 16 imC 8 ]Br wormlike micelles is proposed.

Investigation on thixojoining to produce hybrid components with intermetallic phase

Science.gov (United States)

Seyboldt, Christoph; Liewald, Mathias

2018-05-01

Current research activities at the Institute for Metal Forming Technology of the University of Stuttgart are focusing on the manufacturing of hybrid components using semi-solid forming strategies. One process investigated is the joining of different materials in the semi-solid state and is so called "thixojoining". In this process, metallic inlays are inserted into the semi-solid forming die before the actual forming process and are then joined with a material which was heated up to its semi-solid state. Earlier investigations have shown that using this process a very well-shaped form closure can be produced. Furthermore, it was found that sometimes intermetallic phases are built between the different materials, which decisively influence the part properties of such hybrid components for its future application. Within the framework presented in this paper, inlays made of aluminum, brass and steel were joined with aluminum in the semi-solid state. The aim of the investigations was to create an intermetallic bond between the different materials. For this investigations the liquid phase fraction of the aluminum and the temperature of the inlay were varied in order to determine the influence on the formation of the intermetallic phase. Forming trials were performed using a semi-solid forming die with a disk shaped design. Furthermore, the intermetallic phase built was investigated using microsections.

Interfacial microstructures and solder joint strengths of the Sn-8Zn-3Bi and Sn-9Zn-lAl Pb-free solder pastes on OSP finished printed circuit boards

Energy Technology Data Exchange (ETDEWEB)

Lin, C.-T. [Department of Materials Science and Engineering, National United University, 1 Lein-Da, Kung-Ching Li, Miaoli 36003, Taiwan (China); Electronics and Optoelectronics Research Laboratories, Industrial Technology Research Institute, 195 Section 4, Chung-Hsing Road, Chutung, Hsinchu 31040, Taiwan (China); Hsi, C.-S. [Department of Materials Science and Engineering, National United University, 1 Lein-Da, Kung-Ching Li, Miaoli 36003, Taiwan (China); Wang, M.-C. [Faculty of Fragrance and Cosmetics, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 807, Taiwan (China)], E-mail: mcwang@kmu.edu.tw; Chang, T.-C.; Liang, M.-K. [Electronics and Optoelectronics Research Laboratories, Industrial Technology Research Institute, 195 Section 4, Chung-Hsing Road, Chutung, Hsinchu 31040, Taiwan (China)

2008-07-14

Two kinds of lead-free solders, Sn-8Zn-3Bi and Sn-9Zn-lAl, were used to mount passive components onto printed circuit boards via a re-flow soldering process. The samples were stored at 150 deg. C for 200, 400, 600, 800, and 1100 h. The microstructures of the samples after aged at 150 deg. C for various times were characterized using optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and the analyzed of solder joint shear strengths. The joint strength between Sn-8Zn-3Bi and Cu pad was about 4.0 {+-} 0.3 kg, while the strength between Sn-9Zn-lAl and Cu pad had values of 2.6 {+-} 0.1 kg. Both kinds of solder joints exhibited reduced strengths with increasing aging times. After aging at 150 deg. C for 1100 h, the joints strengths of Sn-8Zn-3Bi and Sn-9Zn-lAl were 1.8 {+-} 0.3 and 1.7 {+-} 0.3 kg, respectively. Both the Sn-8Zn-3Bi and Sn-9Zn-lAl joints showed brittle fracture behaviors. A flat layer of Cu{sub 5}Zn{sub 8} intermetallic compound (IMC) was formed between Sn-8Zn-3Bi solder and Cu pad after reflow. When the aging time was increased to 400 h, Zn-depletion and formation of Cu{sub 6}Sn{sub 5} IMC were observed in the solders due to the interaction between the tin and zinc compounds. The interaction between Sn-9Zn-lAl solder and Cu pad had similar behavior, however, Cu{sub 6}Sn{sub 5} IMC formed in Sn-9Zn-lAl solder when after aging at 150 deg. C for 600 h. As the aging time increased, both types of solders generated clear IMC spalling layers with large and continuous voids. Those voids substantially decreased the joint strength.

Transformation of iron containing constituent intermetallic particles during hydrothermal treatment

DEFF Research Database (Denmark)

Borgaonkar, Shruti; Din, Rameez Ud; Kasama, Takeshi

2018-01-01

in the alloys. Furthermore, electron energy loss spectroscopy analysis revealed that the during the steam treatment, the Fe enriched areas of the Al (Fe-Si) Mn type intermetallic particles were transformed into Fe2O3 and Fe3O4 phases, while energy-dispersive X-ray spectroscopy line profile measurements...... by scanning transmission electron microscope showed that Mn and Si were leached out and incorporated into the surrounding oxide layer. Further, the part of intermetallic phase was transformed into polycrystalline material....

Study and development of NiAl intermetallic coating on hypo-eutectoid steel using highly activated composite granules of the Ni-Al system

Energy Technology Data Exchange (ETDEWEB)

Shahzad, Aamir; Zadorozhnyy, Vladislav Yu.; Pavlov, Mikhail D.; Semenov, Dmitri V.; Kaloshkin, Sergey D. [National Univ. of Science and Technology (MISIS), Moscow (Russian Federation)

2018-01-15

NiAl intermetallic coating thickness of about 50 μm was fabricated on hypo-eutectoid steel by mechanical alloying using pre-activated Ni-Al composite granules as coating material. First, Ni and Al powders were mixed with the composition of Ni-50 at.% Al and mechanically activated in a planetary ball mill, until the composite granules of this powder mixture, having maximum activity (9 cm sec{sup -1}), were formed after 120 min of milling at 200 rpm. The composite granules were then taken out from the planetary ball mill just before the critical time, i. e. the time at which these granules synthesize and convert to an intermetallic NiAl compound. The highly activated composite granules of Ni-Al were then put into the vial of a vibratory ball mill with the substrate on top of the chamber. After mechanical alloying for 60 min in the vibratory ball mill, the composite granules were synthesized fully and heat was produced during the synthesis which helped producing a thick and strong adhesive coating of NiAl intermetallic on the steel substrate. The main advantage of this technique is that not only is time saved but also there is no need for any post mechanical alloying process such as annealing or laser treatment etc. to get homogeneous, strongly bonded intermetallic coatings. X-ray diffraction analysis clearly indicates the formation of NiAl phase. Micro-hardness of the coating and substrate was also measured. The cross-sectional microstructure of the composite granules and the final coating were studied by scanning electron microscopy.

Stability of ZrBe17, and NiBe intermetallics during intermediate temperature oxidation

International Nuclear Information System (INIS)

Chou, T.C.; Nieh, T.G.; Wadsworth, J.

1992-01-01

This paper reports that since the finding of MoSi 2 pest by Fitzer in 1955, a number of intermetallic compounds, e.g., ZrBe 13 , WSi 2 , and NiAl have also been reported to exhibit similar behavior during oxidation in air. For example, Lewis reported that catastrophic failure (total disintegration into powders) occurred in ZrBe 13 when oxidized at 700 degrees C in air. X-ray diffraction analyses revealed that the powders were composed of BeO, ZrO 2 (cubic), Zr 2 Be 17 , and unreacted ZrBe 13 . Regardless of numerous cited incidents of pest in intermetallics, fundamental understanding of pest is very limited. Recently, MoSi 2 pest has been studied in a great detail and fundamental insights to the mechanism of pest have been established. It is found that both single- and ply- crystalline MoSi 2 are susceptible to pest, which leads to the disintegration of test samples into powder consisting of MoO 3 whiskers, SiP 2 clusters, and residual MoSi 2 crystals. Pest is also noted to associate with substantial volume expansion of the samples. Most important, the occurrence of pest is contingent upon the formation of blisters, resulting from volume expansion by oxidation and the evaporation of MoO 3 on the surfaces and grain boundary interfaces

Anomalous magnetic aftereffect in Nd3(Fe,T)29 (T = Ti or Re) intermetallic compounds

International Nuclear Information System (INIS)

Collocott, S.J.; Dunlop, J.B.; Gwan, P.B.

1999-01-01

Full text: The intermetallic compounds Nd 3 (Fe,Ti) 29 and Nd 3 (Fe,Re) 29 order ferromagnetically with Curie Temperatures, T c , of 430 and 370 K respectively. They have a monoclinic crystal structure, space group A2/m (Nd 3 (Fe,Ti) 29 type) with two rare earth sites and eleven Fe(T) sites, which is an intermediate structure between the rhombohedral Th 2 Zn 17 and tetragonal ThMn 12 structures, and is closely related to hexagonal CaCu 5 . Ferromagnetic materials, depending on their magnetic prehistory, may exhibit a time dependent magnetisation. The term 'magnetic aftereffect' is used to describe this behaviour, which may fall into three categories: 1. Reversible or diffusion aftereffect which is associated with the diffusion of impurity atoms or holes within the ferromagnetic lattice. 2. The irreversible or fluctuation aftereffect, which results in a logarithmic time dependence of magnetisation, J(t)=J(0)+Sln(t+t 0 ), where S is the magnetic viscosity and t 0 a parameter to establish the origin of the time scale measurements. 3. Quantum tunnelling of magnetisation which is observed at very low temperatures. A range of magnetic aftereffects have been observed in both Nd 3 (Fe,Ti) 29 and Nd 3 (Fe,Re) 29 . Of particular interest is the case where the material is fully saturated by application of a field in the positive direction, the applied field is then reversed to trace out part of the major demagnetisation curve into the third quadrant, and thence along a recoil curve, such that in zero applied field the magnetisation is zero (H=0, J=0). (This corresponds to dc field magnetisation.) This magnetic prehistory results in two interesting effects; spontaneous remagnetisation e.g. remagnetisation without application of an external field, and thermal remagnetisation e.g. an increase in magnetisation as the temperature is increased. Additionally, the behaviour of the magnetic viscosity has been explored on the major demagnetisation curve as a function of temperature

Limitations of Feedback, Feedforward and IMC Controller for a First Order Non-Linear Process with Dead Time

Directory of Open Access Journals (Sweden)

Maruthai Suresh

2010-10-01

Full Text Available A nonlinear process, the heat exchanger whose parameters vary with respect to the process variable, is considered. The time constant and gain of the chosen process vary as a function of temperature. The limitations of the conventional feedback controller tuned using Ziegler-Nichols settings for the chosen process are brought out. The servo and regulatory responses through simulation and experimentation for various magnitudes of set-point changes and load changes at various operating points with the controller tuned only at a chosen nominal operating point are obtained and analyzed. Regulatory responses for output load changes are studied. The efficiency of feedforward controller and the effects of modeling error have been brought out. An IMC based system is presented to understand clearly how variations of system parameters affect the performance of the controller. The present work illustrates the effectiveness of Feedforward and IMC controller.

Crystal Growth and Characterization of MT2Si2 Ternary Intermetallics (M = U, RE and T = 3d, 4d, 5d Transition Metals)

NARCIS (Netherlands)

Menovsky, A.A.; Moleman, A.C.; Snel, G.E.; Gortenmulder, T.J.; Palstra, T.T.M.

1986-01-01

Bulk single crystals of the ternary intermetallic compounds UT2Si2 (T = Ni, Pd, Pt and Ru), LaT2Si2 (T = Pd and Rh) and LuPd2Si2 have been grown from the melt with a modified “tri-arc” Czochralski method. The as-grown crystals were characterized by X-ray, microprobe and chemical analyses. The

Structural plasticity: how intermetallics deform themselves in response to chemical pressure, and the complex structures that result.

Science.gov (United States)

Berns, Veronica M; Fredrickson, Daniel C

2014-10-06

Interfaces between periodic domains play a crucial role in the properties of metallic materials, as is vividly illustrated by the way in which the familiar malleability of many metals arises from the formation and migration of dislocations. In complex intermetallics, such interfaces can occur as an integral part of the ground-state crystal structure, rather than as defects, resulting in such marvels as the NaCd2 structure (whose giant cubic unit cell contains more than 1000 atoms). However, the sources of the periodic interfaces in intermetallics remain mysterious, unlike the dislocations in simple metals, which can be associated with the exertion of physical stresses. In this Article, we propose and explore the concept of structural plasticity, the hypothesis that interfaces in complex intermetallic structures similarly result from stresses, but ones that are inherent in a defect-free parent structure, rather than being externally applied. Using DFT-chemical pressure analysis, we show how the complex structures of Ca2Ag7 (Yb2Ag7 type), Ca14Cd51 (Gd14Ag51 type), and the 1/1 Tsai-type quasicrystal approximant CaCd6 (YCd6 type) can all be traced to large negative pressures around the Ca atoms of a common progenitor structure, the CaCu5 type with its simple hexagonal 6-atom unit cell. Two structural paths are found by which the compounds provide relief to the Ca atoms' negative pressures: a Ca-rich pathway, where lower coordination numbers are achieved through defects eliminating transition metal (TM) atoms from the structure; and a TM-rich path, along which the addition of spacer Cd atoms provides the Ca coordination environments greater independence from each other as they contract. The common origins of these structures in the presence of stresses within a single parent structure highlights the diverse paths by which intermetallics can cope with competing interactions, and the role that structural plasticity may play in navigating this diversity.

Study of hyperfine interactions in intermetallic compounds Gd(Ni,Pd,Cu)In, Tb(Ni,Pd)In, Dy(Ni,Pd)In and Ho(Ni,Pd)In; Estudo de interacoes hiperfinas em compostos intermetalicos Gd(Ni,Pd,Cu)In, Tb(Ni,Pd)In, Dy(Ni,Pd)In e Ho(Ni,Pd)In

Energy Technology Data Exchange (ETDEWEB)

Lapolli, Andre Luis

2006-07-01

Systematic behavior of magnetic hyperfine field (B{sub hf}) in the intermetallic compounds Gd(Ni,Pd,Cu)In Tb(Ni,Pd)In, Dy(Ni,Pd)In and Ho(Ni,Pd)In was studied by Perturbed Gamma-Gamma Angular Correlation spectroscopy. The measurements of B{sub hf} were carried out at the rare earth atom and in sites using the nuclear probes {sup 140}Ce and {sup 11}'1Cd respectively. The variation of hyperfine field with temperature, in most cases, follows the Brillouin function predicted from the molecular field theory. The hyperfine field values at rare earth atom sites obtained from {sup 140}Ce probe as well as at in sites obtained from {sup 111}Cd probe for each series of compounds were extrapolated to zero Kelvin B{sub hf}(T=0) from these curves. These values were compared with the values of the literature for other compounds containing the same rare earth element and all of them show a linear relationship with the ordering temperature. This indicates that the main contribution to B{sub hf} comes from the conduction electron polarization (CEP) through Fermi contact interaction and the principal mechanism of magnetic interaction in these compounds can be described by the RKKY type interaction. The values of B{sub hf}(T=0) for each family of intermetallic compounds RNiIn and RPdIn when plotted as a function of 4f spin projection of rare earth element also shows a linear relationship. Exceptions are the results for the compounds RNiIn obtained with {sup 111}Cd probe where a small deviation from linearity is observed. The results of the measurements carried out with the {sup 111}Cd probe were also analyzed to obtain the hyperfine parameters of the quadrupole interaction as a function of temperature for RPdln and GdNiIn compounds. The results show that for the compound GdPdIn there might be some Gd-In disorder at high temperature. (author)

Study of hyperfine interactions in intermetallic compounds Gd(Ni,Pd,Cu)In, Tb(Ni,Pd)In, Dy(Ni,Pd)In and Ho(Ni,Pd)In; Estudo de interacoes hiperfinas em compostos intermetalicos Gd(Ni,Pd,Cu)In, Tb(Ni,Pd)In, Dy(Ni,Pd)In e Ho(Ni,Pd)In

Energy Technology Data Exchange (ETDEWEB)

Lapolli, Andre Luis

2006-07-01

Systematic behavior of magnetic hyperfine field (B{sub hf}) in the intermetallic compounds Gd(Ni,Pd,Cu)In Tb(Ni,Pd)In, Dy(Ni,Pd)In and Ho(Ni,Pd)In was studied by Perturbed Gamma-Gamma Angular Correlation spectroscopy. The measurements of B{sub hf} were carried out at the rare earth atom and in sites using the nuclear probes {sup 140}Ce and {sup 11}'1Cd respectively. The variation of hyperfine field with temperature, in most cases, follows the Brillouin function predicted from the molecular field theory. The hyperfine field values at rare earth atom sites obtained from {sup 140}Ce probe as well as at in sites obtained from {sup 111}Cd probe for each series of compounds were extrapolated to zero Kelvin B{sub hf}(T=0) from these curves. These values were compared with the values of the literature for other compounds containing the same rare earth element and all of them show a linear relationship with the ordering temperature. This indicates that the main contribution to B{sub hf} comes from the conduction electron polarization (CEP) through Fermi contact interaction and the principal mechanism of magnetic interaction in these compounds can be described by the RKKY type interaction. The values of B{sub hf}(T=0) for each family of intermetallic compounds RNiIn and RPdIn when plotted as a function of 4f spin projection of rare earth element also shows a linear relationship. Exceptions are the results for the compounds RNiIn obtained with {sup 111}Cd probe where a small deviation from linearity is observed. The results of the measurements carried out with the {sup 111}Cd probe were also analyzed to obtain the hyperfine parameters of the quadrupole interaction as a function of temperature for RPdln and GdNiIn compounds. The results show that for the compound GdPdIn there might be some Gd-In disorder at high temperature. (author)

Uranium magnetism in UGa2 and U(Gasub(1-x)Alsub(x))2 compounds

International Nuclear Information System (INIS)

Ballou, R.

1983-01-01

Magnetism of intermetallic compounds of uranium is studied. A monocrystal of the highly anisotropic ferromagnetic material UGa 2 is studied by polarized neutron diffraction. Localisation of 5f electrons is evidenced. Magnetic structure of uranium in UGa 2 is determined. The pseudobinary compound U(Gasub(1-x)Alsub(x)) 2 is studied for crystal structure, ferromagnetism, paramagnetism, specific heat and resistivity [fr

The Ni3Al and NiAl alloys: a class of intermetallics which can replace the Ni-base superalloys for the aerospace high temperature structural applications

International Nuclear Information System (INIS)

Lucaci, M.; Vidu, C.D.; Vasile, E.

2001-01-01

The paper presents the results obtained in synthesizing Ni-base refractory intermetallics from elemental powder mixes. In view of this, four mixes were made for the Ni 3 Al intermetallics and five mixes for the NiAl ones. The compound synthesis was made at T = 660 o C under vacuum by the SHS method, in the thermo-explosion mode. The variable parameters were the compacting pressure and the aluminum amount in the mixes. The obtained materials were then characterized by the microstructure and by the physical properties. The product synthesis degree was followed as well as their influence on the types of microstructures obtained. The reaction products were evidenced by x-ray diffraction and by quantitative chemical microanalysis. The obtained results revealed the formation of the Ni 3 Al compound having a primitive cubic crystal lattice with a 0 = 3,564 Aa and the formation of the NiAl compound, of a bcc lattice having a 0 = 2,86 Aa. Those obtained prove the ample influences of the powder homogeneity degree and of the powder purity on the possibility to produce an adequate synthesis, as well as the influence of the amount liquid appeared in the system on the synthesis degree, on the reaction rate and on the porosity of materials obtained. (author)

Dominant effect of high anisotropy in β-Sn grain on electromigration-induced failure mechanism in Sn-3.0Ag-0.5Cu interconnect

Energy Technology Data Exchange (ETDEWEB)

Huang, M.L., E-mail: huang@dlut.edu.cn; Zhao, J.F.; Zhang, Z.J.; Zhao, N.

2016-09-05

The effect of high diffusivity anisotropy in β-Sn grain on electromigration behavior of micro-bumps was clearly demonstrated using Sn-3.0Ag-0.5Cu solder interconnects with only two β-Sn grains. The orientation of β-Sn grain (θ is defined as the angle between the c-axis of β-Sn grain and the electron flow direction) is becoming the most crucial factor to dominate the different electromigration-induced failure modes: 1) the excessive dissolution of the cathode Cu, blocking at the grain boundary and massive precipitation of columnar Cu{sub 6}Sn{sub 5} intermetallic compounds (IMCs) in the small angle θ β-Sn grain occur when electrons flow from a small angle θ β-Sn grain to a large one; 2) void formation and propagation occur at the cathode IMC/solder interface and no Cu{sub 6}Sn{sub 5} IMCs precipitate within the large angle θ β-Sn grain when electrons flow in the opposite direction. The EM-induced failure mechanism of the two β-Sn grain solder interconnects is well explained in viewpoint of atomic diffusion flux in β-Sn. - Highlights: • High anisotropy in β-Sn dominates different electromigration-induced failure mode. • Excessive dissolution of cathode Cu occurs if electrons flow in forward direction. • Voids initiate and propagate at cathode if electrons flow in reverse direction. • Failure modes are well explained in viewpoint of atomic diffusion flux in β-Sn.

Investigation of electronic structure and chemical bonding of intermetallic Pd2HfIn: An ab-initio study

Science.gov (United States)

Bano, Amreen; Gaur, N. K.

2018-05-01

Ab-initio calculations are carried out to study the electronic and chemical bonding properties of Intermetallic full Heusler compound Pd2HfIn which crystallizes in F-43m structure. All calculations are performed by using density functional theory (DFT) based code Quantum Espresso. Generalized gradient approximations (GGA) of Perdew- Burke- Ernzerhof (PBE) have been adopted for exchange-correlation potential. Calculated electronic band structure reveals the metallic character of the compound. From partial density of states (PDoS), we found the presence of relatively high intensity electronic states of 4d-Pd atom at Fermi level. We have found a pseudo-gap just abouve the Fermi level and N(E) at Fermi level is observed to be 0.8 states/eV, these finding indicates the existence of superconducting character in Pd2HfIn.

Simulation of the precipitation process of ordered intermetallic compounds in binary and ternary Ni-Al-based alloys by the phase-field model

International Nuclear Information System (INIS)

Hou Hua; Zhao Yuhong; Zhao Yuhui

2009-01-01

With the microscopic phase-field model, atomic-scale computer simulation programs for the precipitation mechanism of the ordered intermetallic compound γ' in binary Ni-15.5 at.%Al alloy, θ and γ' in ternary Ni 75 Al x V 25-x alloys were worked out based on the microscopic diffusion equation and non-equilibrium free energy. The simulation can be applied to the whole precipitation process and composition range. A prior assumptions on the new phase structure or transformation path was unnecessary, the possible non-equilibrium phases, atomic clustering and ordering could be described automatically, and atomic images, order parameters and volume fractions of precipitates were obtained. Computer simulation was performed systematically on the precipitation mechanism, precipitation sequence of θ and γ' in complicated system with ordering and clustering simultaneously. Through the simulated atomic images and chemical order parameters of precipitates, we can explain the complex precipitation mechanisms of θ (Ni 3 V) and γ' (Ni 3 Al) ordered phases. For the binary alloy, the precipitation mechanism of γ' phase has the characteristic of both non-classical nucleation and growth (NCNG) and congruent ordering and spinodal decomposition (COSD). For the ternary alloys, the precipitation characteristic of γ' phase transforms from NCNG to COSD gradually, otherwise, the precipitation characteristic of θ phase transforms from COSD to NCNG mechanism gradually

The nucleation and growth of intermetallic Al-Pt phases

International Nuclear Information System (INIS)

Kovacs, A.; Barna, P.B.; Labar, J. l.

2002-01-01

The nucleation and growth of intermetallic Al-Pt phases on amorphous carbon was investigated by half shadow technique in co-deposited thin films. In such experimental condition, the composition of the deposited films varied in the range of Al x Pt 1-x (0≤x≤0.6). The coexistence of Al 5 Pt, Al 2 Pt, Al 3 Pt 2 intermetallic phases have been found in the whole range with varying ratio. Vapour depositions were performed in an UHV system. The Al and Pt components were evaporated simultaneously onto amorphous carbon layer supported by TEM micro-grids. Deposition rates were controlled separately by quartz crystal monitors. Substrate temperature during deposition was 350 grad C. A special evaporation arrangement made possible to create a half shadow area on the substrate in which the quantity one of the components increased from zero to the wanted composition of the sample. The composition of the zones was determined by energy dispersive X-ray spectroscopy (EDS) in TEM. The intermetallic phases developed in the sample were investigated by analytical TEM (Philips CM20) and high resolution TEM (JEOL 3010 UHR). The electron diffraction patterns have been evaluated by ProcessDiffraction program. (Authors)

First principles study of halogens adsorption on intermetallic surfaces

International Nuclear Information System (INIS)

Zhu, Quanxi; Wang, Shao-qing

2016-01-01

Graphical abstract: - Highlights: • The linear relation between adsorbates induced work function change and dipole moment change also exists for intermetallic surfaces. • It is just a common linear relationship rather than a directly proportion. • A new weight parameter β is proposed to describe different factors effect on work function shift. - Abstract: Halides are often present at electrochemical environment, they can directly influence the electrode potential or zero charge potential through the induced work-function change. In this work, we focused in particular on the halogen-induced work function change as a function of the coverage of fluorine, chlorine, bromine and iodine on Al_2Au and Al_2Pt (110) surfaces. Results show that the real relation between work function change and dipole moment change for halogens adsorption on intermetallic surfaces is just a common linear relationship rather than a directly proportion. Besides, the different slopes between fitted lines and the theoretical slope employed in pure metal surfaces demonstrating that the halogens adsorption on intermetallic surfaces are more complicated. We also present a weight parameter β to describe different factors effect on work function shift and finally qualify which factor dominates the shift direction.

Effects of Nb content on the Zr2Fe intermetallic stability

International Nuclear Information System (INIS)

Ramos, C.; Saragovi, C.; Granovsky, M.; Arias, D.

2003-01-01

With the aim of studying the stability range of the Zr 2 Fe intermetallic when adding Nb, the range of existence of the cubic ternary phase (λ 1 ) and the corresponding two-phase field between them, four samples were analyzed, each one containing 35 at.% Fe and different at.% Nb: 0.5, 4 10 and 15. Optical and scanning electron metallographies, X-ray diffraction, microprobe analysis and Moessbauer spectroscopy were performed to determine and characterize the phases present in the samples. Results show that the Zr 2 Fe compound accepts up to nearly 0.5 at.% Nb in solution, since the Zr 2 Fe+λ 1 region is stable in the (0.5-3.5) at.% Nb range. To summarize these results an 800 deg. C section of the ternary Zr-Nb-Fe diagram, in the studied zone, was proposed

Temperature effects in the valence fluctuation of europium intermetallic compounds

International Nuclear Information System (INIS)

Menezes, O.L.T. de; Troper, A.; Gomes, A.A.

1978-03-01

A previously reported model for valence fluctuations in europium compound in order to account for thermal occupation effect. Experimental results are critically discussed and new experiments are suggested

Synthesis and studies on structural, optical and nonlinear optical properties of novel organic inter-molecular compounds: 4-chloro-3-nitroaniline-3-hydroxy benzaldehyde and urea-4-dimethylaminopyridine

Science.gov (United States)

Pandey, Priyanka; Rai, R. N.

2018-05-01

Two novel organic inter-molecular compounds (IMCs), (3-(4-chloro-3-nitrophenylimino) methyl) phenol) (CNMP) and urea ̶ 4-dimethylaminopyridine complex (UDMAP), have been synthesized by solid state reaction. These two IMCs were identified by phase diagram study of CNA-HB and U-DMAP systems. The single crystals of newly obtained IMCs were grown by slow solvent evaporation technique at room temperature. Both the IMCs were further studied for their thermal, spectral, single crystal XRD for their atomic packing in molecule, crystallinity, optical and nonlinear optical behaviour. In both the cases, melting point of inter-molecular compounds was found to be higher than that of their parent components, CNMP was found to be thermally stable up to 158 °C while UDMAP was stable up to 144 °C, which indicate their extra stability than their parents. The single crystal XRD studies confirmed that CNMP has crystallized in orthorhombic unit cell with non-centrosymmetric space group P212121 while UDMAP has crystallized in monoclinic unit cell with centrosymmetric space group C2/c. The absorption spectrum of CNMP was found to be in between the absorption of parents, while broadening of peak and red shift was observed in UDMAP as compared to the parents. Second order nonlinear optical property of CNMP and UDMAP was studied using Kurtz Perry powder technique and intense green light emission was observed with CNMP on excitation with 1064 nm of Nd:YAG laser while no emission was observed with UDMAP.

Enhanced IMC design of load disturbance rejection for integrating and unstable processes with slow dynamics.

Science.gov (United States)

Liu, Tao; Gao, Furong

2011-04-01

In view of the deficiencies in existing internal model control (IMC)-based methods for load disturbance rejection for integrating and unstable processes with slow dynamics, a modified IMC-based controller design is proposed to deal with step- or ramp-type load disturbance that is often encountered in engineering practices. By classifying the ways through which such load disturbance enters into the process, analytical controller formulae are correspondingly developed, based on a two-degree-of-freedom (2DOF) control structure that allows for separate optimization of load disturbance rejection from setpoint tracking. An obvious merit is that there is only a single adjustable parameter in the proposed controller, which in essence corresponds to the time constant of the closed-loop transfer function for load disturbance rejection, and can be monotonically tuned to meet a good trade-off between disturbance rejection performance and closed-loop robust stability. At the same time, robust tuning constraints are given to accommodate process uncertainties in practice. Illustrative examples from the recent literature are used to show effectiveness and merits of the proposed method for different cases of load disturbance. Copyright © 2010. Published by Elsevier Ltd.

Green synthesis, characterization and some physico-chemical studies on a novel intermolecular compound; 4-nitro-o-phenylenediamine-N, N-dimethylaminobenzaldehyde system

Science.gov (United States)

Rai, U. S.; Singh, Manjeet; Rai, R. N.

2017-09-01

An inter-molecular compound (IMC) L1 was synthesized by taking 1:1 molar ratio of p-nitro-o-phenylenediamine (NOPDA) and N, N-dimethylaminobenzaldehyde (DMAB) via thermally initiated solid state reaction. It was characterized by X-ray diffraction, spectral and optical studies. The single crystal of the (L1) was grown from saturated solution of ethanol using slow evaporation technique at 29 °C. From the single crystal X-ray diffraction analysis, it can be inferred that it crystallizes in triclinic unit cell with P-1 space group (CCDC No 1422765). Absorption spectrum of IMC (L1) shows a band at 318 nm attributed to the intra-molecular charge-transfer (ICT) excited state absorption and the other band at 376 nm is due to n→π* transition. The IMC (L1) shows a strong fluorescence at 418 nm with a Stokes shift (≈100 nm) and quantum efficiency (0.22) upon excitation in methyl alcohol at 318 nm.

Reliable and cost effective design of intermetallic Ni2Si nanowires and direct characterization of its mechanical properties

OpenAIRE

Seung Zeon Han; Joonhee Kang; Sung-Dae Kim; Si-Young Choi; Hyung Giun Kim; Jehyun Lee; Kwangho Kim; Sung Hwan Lim; Byungchan Han

2015-01-01

We report that a single crystal Ni2Si nanowire (NW) of intermetallic compound can be reliably designed using simple three-step processes: casting a ternary Cu-Ni-Si alloy, nucleate and growth of Ni2Si NWs as embedded in the alloy matrix via designing discontinuous precipitation (DP) of Ni2Si nanoparticles and thermal aging, and finally chemical etching to decouple the Ni2Si NWs from the alloy matrix. By direct application of uniaxial tensile tests to the Ni2Si NW we characterize its mechanica...

Influence of intermetallic growth on the mechanical properties of Zn–Sn–Cu–Bi/Cu solder joints

Energy Technology Data Exchange (ETDEWEB)

Xing, Fei; Yao, Jia; Liang, Jingwei; Qiu, Xiaoming, E-mail: qiuxm13@163.com

2015-11-15

The formation of intermetallic reaction layers and their influence on shear strength and fractography was investigated between the Zn–Sn–Cu–Bi (ZSCB) and Cu substrate during the liquid state reaction at 450 °C after 10–90 s. Results showed that reliable solder joints could be obtained at 450 °C after 15–30 s of wetting, accompanied by the creation of scallop ε-CuZn{sub 5}, flat γ-Cu{sub 5}Zn{sub 8} and β-CuZn intermetallic layers in ZSCB/Cu interface. However, with excess increase of soldering time, a transient intermetallic ε-CuZn{sub 4} phase was nuclear and grew at ε-CuZn{sub 5}/γ-Cu{sub 5}Zn{sub 8} interface, which apparently deteriorated the shear strength of solder joints from 76.5 MPa to 51.6 MPa. The sensitivity of the fracture proportion was gradually transformed from monotonic ε-CuZn{sub 5} to the mixture of ε-CuZn{sub 4} and ε-CuZn{sub 5} intermetallic cleavage. Furthermore, the growth mechanism of ε-CuZn{sub 4} intermetallic phase at the ZSCB/Cu interface was discussed. - Highlights: • There are four interfacial intermetallic layers formed at the Zn–Sn–Cu–Bi/Cu interface. • The growth mechanism of ε-CuZn{sub 4} intermetallic phase was discussed. • The wetting time of Zn–Sn–Cu–Bi solder in contact with Cu substrate is a key parameter.

Studies in group IV organometallic chemistry XXX. Synthesis of compounds containing tin---titanium and tin---zirconium bonds

NARCIS (Netherlands)

Creemers, H.M.J.C.; Verbeek, F.; Noltes, J.G.

1968-01-01

Starting from the tetrakis(diethylamino) derivatives of titanium and zirconium and pheyltin hydrides six intermetalic compounds contianing up to nine tin and titanium(or zirconium) atoms have been obtained by hydrostannolysis type reactions.

Microstructure and phase constitution near the interface of Cu/3003 torch brazing using Al Si La Sr filler

International Nuclear Information System (INIS)

Yan, Fei; Wang, Chun Ming; Wang, Ya Jun; Xu, Dao Rong; Wu, S.C.; Sun, Qin De

2012-01-01

It has been mainly studied in this paper on brazing of Cu to Al using Al.Si filler metal. The optimized scanning rate of 2.5 mm/s is first obtained through simulating the temperature field of Cu Al brazing process based on ANSYS software. Then the brazing of Cu C11000 to Al 3003 using Al.Si.La.Sr filler is carried out by torch brazing technology. It is found that the brazing seam region is mainly consisted of α Al solid solution and CuAl2 IMC. Further experimental results also show that the rare earth element La in filler metal can not only refine the grain, but also promote the dispersion of intermetallic compounds into the brazing seam, which significantly improves the brazing seam microstructure and mechanical properties of the joints

Magnetocaloric effect in rare-earth intermetallics: Recent trends

Indian Academy of Sciences (India)

... intermetallic hydrides, manganite oxides, Ni–Mn–Sb-type shape memory ... With the help of temperature-dependent heat capacity information in various applied .... for relative cooling power and a wide working temperature range of about ...

Theoretical energy release of thermites, intermetallics, and combustible metals

Energy Technology Data Exchange (ETDEWEB)

Fischer, S.H.; Grubelich, M.C.

1998-06-01

Thermite (metal oxide) mixtures, intermetallic reactants, and metal fuels have long been used in pyrotechnic applications. Advantages of these systems typically include high energy density, impact insensitivity, high combustion temperature, and a wide range of gas production. They generally exhibit high temperature stability, and possess insensitive ignition properties. In this paper, the authors review the applications, benefits, and characteristics of thermite mixtures, intermetallic reactants, and metal fuels. Calculated values for reactant density, heat of reaction (per unit mass and per unit volume), and reaction temperature (without and with consideration of phase changes and the variation of specific heat values) are tabulated. These data are ranked in several ways, according to density, heat of reaction, reaction temperature, and gas production.

Investigation of passivity and its breakdown on Fe3Al–Si and Fe3Al–Ge intermetallics in chloride-containing solution

International Nuclear Information System (INIS)

Rosalbino, F.; Carlini, R.; Parodi, R.; Zanicchi, G.; Scavino, G.

2014-01-01

Highlights: • Passivity and its breakdown on Fe 3 Al–Si and Fe 3 Al–Ge iron aluminides was investigated. • Investigation was performed in borate buffer solution with and without 100 mM KCl. • Polarization, potentiostatic transients and impedance measurements have been employed. • Results have been compared with those obtained on Fe 3 Al intermetallic. • Si and Ge improve the resistance to localized corrosion of Fe 3 Al. - Abstract: The passivity and passivity breakdown of Fe 3 Al–Si and Fe 3 Al–Ge iron aluminides were studied in borate buffer solution (pH 8.4) in the absence and presence of 100 mM KCl, performing potentiodynamic polarization, potentiostatic transients and electrochemical impedance spectroscopy (EIS) measurements complemented with scanning electron microscopy (SEM). In the absence of chloride ions Si and Ge exercise a beneficial role in the passivating characteristics of Fe 3 Al intermetallic. Addition of Si or Ge significantly modifies the electrochemical response of iron aluminide Fe 3 Al resulting in a more stable passive film. In the presence of chloride ions all the intermetallic compounds experience localized corrosion (pitting). However, Si and Ge alloying additions increase the breakdown potential and the extent of passivation domain, indicating improved resistance to initiation of pitting corrosion. Furthermore, EIS measurements performed at the breakdown state evidenced higher R ct and lower depression angle values for Fe 3 Al–Si and Fe 3 Al–Ge iron aluminides compared to Fe 3 Al intermetallic, confirming their better localized corrosion behavior. The improved resistance to pitting corrosion results from the enhanced protective function of passive film due to the presence of Si or Ge that inhibit pit initiation by hindering the adsorption of Cl − ions at the metal surface

Femtosecond laser ablation and nanoparticle formation in intermetallic NiAl

Energy Technology Data Exchange (ETDEWEB)

Jorgensen, David J., E-mail: davidjjorgensen@engr.ucsb.edu; Titus, Michael S.; Pollock, Tresa M.

2015-10-30

Highlights: • The single-pulse fs laser ablation threshold of NiAl is 83 mJ/cm{sup 2}. • The transition between low- and high-fluence ablation regimes is 2.8 J/cm{sup 2}. • A bimodal size distribution of nanoparticles is formed with fs laser ablation. • Smaller nanoparticles are enriched in Al during pulsed fs laser ablation. • The target surface is depleted in Al during pulsed fs laser ablation. - Abstract: The ablation behavior of a stoichiometric intermetallic compound β-NiAl subjected to femtosecond laser pulsing in air has been investigated. The single-pulse ablation threshold for NiAl was determined to be 83 ± 4 mJ/cm{sup 2} and the transition to the high-fluence ablation regime occurred at 2.8 ± 0.3 J/cm{sup 2}. Two sizes of nanoparticles consisting of Al, NiAl, Ni{sub 3}Al and NiO were formed and ejected from the target during high-fluence ablation. Chemical analysis revealed that smaller nanoparticles (1–30 nm) tended to be rich in Al while larger nanoparticles (>100 nm) were lean in Al. Ablation in the low-fluence regime maintained this trend. Redeposited material and nanoparticles remaining on the surface after a single 3.7 J/cm{sup 2} pulse, one hundred 1.7 J/cm{sup 2} pulses, or one thousand 250 mJ/cm{sup 2} pulses were enriched in Al relative to the bulk target composition. Further, the surface of the irradiated high-fluence region was depleted in Al indicating that the fs laser ablation removal rate of the intermetallic constituents in this regime does not scale with the individual pure element ablation thresholds.

Design of an Image Motion Compenstaion (IMC Algorithm for Image Registration of the Communication, Ocean, Meteorolotical Satellite (COMS-1

Directory of Open Access Journals (Sweden)

Taek Seo Jung

2006-03-01

Full Text Available This paper presents an Image Motion Compensation (IMC algorithm for the Korea's Communication, Ocean, and Meteorological Satellite (COMS-1. An IMC algorithm is a priority component of image registration in Image Navigation and Registration (INR system to locate and register radiometric image data. Due to various perturbations, a satellite has orbit and attitude errors with respect to a reference motion. These errors cause depointing of the imager aiming direction, and in consequence cause image distortions. To correct the depointing of the imager aiming direction, a compensation algorithm is designed by adapting different equations from those used for the GOES satellites. The capability of the algorithm is compared with that of existing algorithm applied to the GOES's INR system. The algorithm developed in this paper improves pointing accuracy by 40%, and efficiently compensates the depointings of the imager aiming direction.

Longitudinal recording on FePt and FePtX (X = B, Ni) intermetallic compounds

Science.gov (United States)

Li, Ning

1999-11-01

Near field recording on high coercivity FePt intermetallic compound media using a high Bsat write element was investigated. Untextured FePt media were prepared by magnetron sputtering on ZrO2 disks at a substrate temperature of 450°C, with post annealing at 450°C for 8 hrs. Both multilayer and cosputtered precursors produced the ordered tetragonal L10 phase with high coercivity between 5kOe and 12kOe. To improve readback noise decrease magnetic domain size, FePtB media were subsequently prepared by cosputtering. Over-write, roll-off, signal to noise ratio and non-linear transition shift (NLTS) ere measured by both metal in gap (MIG) and merged MR heads. FePtB media showed similar NLTS to commercial CoCrPtTa longitudinal media, but 5dB lower signal to noise ratio. By operating recording transducers in near contact, reasonable values of (>30dB) could be obtained. VSM Rotational Transverse Magnetization has been used for measuring the anisotropy field of magnetic thin films. Magnetization reversal during rotation of a 2D isotropic an applied field is discussed. The relationship between the transverse magnetization My and the applied field H was numerically solved. An excellent approximation for the transverse magnetization is found to be: My/Ms=A(1- H/Hk) 2.5, where A = 1.1434, and Hk is the anisotropy field. For curve fitting to experimental data, both A and Hk were used as fitting parameters. Comparison between a constructed torque hysteresis method and this VSM RTM method have been made theoretically and experimentally. Both results showed that VSM RTM will give better extrapolation of the anisotropy field. The torque measurement will slightly overestimate the anisotropy field. The anisotropy fields of FePt and FePtX (X = B, Ni) films were characterized using this VSM RTM technique with comparison to a CoCrTaPt disk. Anisotropy energy was derived. Hc/Hk was used as an indicator for coherent rotation of a single domain. Interactions between magnetic domains were

Intermetallic matrix composites; Proceedings of the MRS Symposium, San Francisco, CA, Apr. 18-20, 1990

International Nuclear Information System (INIS)

Anton, D.L.; Martin, P.L.; Miracle, D.B.; Mcmeeking, R.

1990-01-01

The present volume on intermetallic matrix composites discusses the modeling, processing, microstructure/property relationships, and compatibility of intermetallic matrix composites. Attention is given to models for the strength of ductile matrix composites, innovative processing techniques for intermetallic matrix composites, ductile phase toughening of brittle intermetallics, and reactive synthesis of NbAl3 matrix composites. Topics addressed include solidification processing of NbCr2 alloys, Ta and Nb reinforced MoSi2, the microstructure and mechanical behavior of Ni3Al-matrix composites, and ductile-phase toughening of Cr3Si with chromium. Also discussed are dislocation morphologies in TiB2/NiAl, the development of highly impact resistant NiAl matrix composites, the effect of notches on the fatigue life of the SCS-6Ti3Al composite, and the chemical stability of fiber-metal matrix composites

Atom probe tomography of intermetallic phases and interfaces formed in dissimilar joining between Al alloys and steel

International Nuclear Information System (INIS)

Lemmens, B.; Springer, H.; Duarte, M.J.; De Graeve, I.; De Strycker, J.; Raabe, D.; Verbeken, K.

2016-01-01

While Si additions to Al are widely used to reduce the thickness of the brittle intermetallic seam formed at the interface during joining of Al alloys to steel, the underlying mechanisms are not clarified yet. The developed approach for the site specific atom probe tomography analysis revealed Si enrichments at grain and phase boundaries between the θ (Fe 4 Al 13 ) and η (Fe 2 Al 5 ) phase, up to about ten times that of the concentration in Al. The increase in Si concentration could play an important role for the growth kinetics of the intermetallic phases formed for example in hot-dip aluminizing of steel. - Highlights: •Si additions to Al reduce thickness of intermetallic seam in joining with steel. •Approach developed for the site specific APT analysis of the intermetallic seam •Si enrichment at grain and phase boundaries possibly affects growth of intermetallics.

Pressure induced helimagnetism in Fe-based (Y.sub.2./sub.Fe.sub.17./sub., Lu.sub.2./sub.Fe.sub.17./sub.) intermetallic compounds

Czech Academy of Sciences Publication Activity Database

Kamarád, Jiří; Prokhnenko, Olexandr; Prokeš, K.; Arnold, Zdeněk; Andreev, Alexander V.

2007-01-01

Roč. 310, - (2007), s. 1801-1803 ISSN 0304-8853 R&D Projects: GA ČR GA202/06/0178 Institutional research plan: CEZ:AV0Z10100521 Keywords : magnetic structure * Fe-base intermetallics * Y 2 Fe 17 * pressure effects Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.704, year: 2007

State diagram of U-Al-Si as a basis for analysis of the processes in nuclear fuel compositions based on U(Al, Si)3 and U3Si compounds

International Nuclear Information System (INIS)

Chebotarev, N.T.; Konovalov, L.N.; Zhmak, V.A.; Chebotarev, Ya.N.

1996-01-01

Results of studies into the Al-UAl 3 -USi 3 -Si of the U-Al-Si ternary system are presented. It is established that phase equilibrium between the intermetallic compound U(Al, Si) 3 and the aluminium-silicon alloys may be presented in form of conodes on the isothermal cross-section of the state diagram. It is shown that the U(Al, Si) 3 intermetallic compound, containing up to 6.5 at.% silicon, interacts both with liquid and solid aluminium with the U(Al, Si) 4 phase formation [ru

Reaction kinetics of the formation of intermetallic Fe – Zn during hot - dip galvanizing of steel

Directory of Open Access Journals (Sweden)

P. Pokorny

2016-01-01

Full Text Available This review article mainly describes the composition of intermetallic Fe - Zn, i.e. zeta (ζ, delta (δ1k + δ1p, gamma1 (Γ1 and gamma (Γ on galvanized steel during low temperature galvanization (t ~ 450 °C. It gives detailed the formation, growth of individual phases during galvanization and their interaction. In terms of the kinetics, the formation of the coating is defined by a parabolic kinetic equation of the growth of different intermetallic phases under ideal conditions. From the available literature the rate constants of the formation of individual intermetallic phases and also for the total coating are cited. The composition of the intermetallic phases, iron content, crystal structure, and group symmetry in which the surface of galvanized steel forms.

Formation of abrasion-resistant coatings of the AlSiFe{sub x}Mny intermetallic compound type on the AISI 304L alloy

Energy Technology Data Exchange (ETDEWEB)

Martinez-Peralez, L. G.; Flores-Valdes, A.; Salinas-Rodriguez, A.; Ochoa-Palacios, R. M.; Toscano-giles, J. A.; Torres-Torres, J.

2016-05-01

The α-Al{sub 9}FeMnSi and α-Al{sub 9}FeMn{sub 2}Si intermetallics formed by reactive sintering of Al, Si, Mn, Fe, Cr and Ni powders have been used in AISI 304L steels to enhance microhardness. Processing variables of the reactive sintering treatment were temperature (600, 650, 700, 750 and 800 degree centigrade), pressure (5, 10 y 20 MPa) and holding time (3600, 5400 y 7200 seconds). Experimental results show that temperature is the most important variable affecting the substrate/coating formation, while pressure does not appear to have a significant effect. The results show the optimum conditions of the reactive sintering that favor the substrate/coating formation are 800 degree centigrade, 20 MPa and 7200 seconds. Under these conditions, the reaction zone between the substrate and coating is more compacted and well-adhered, with a microhardness of 1300 Vickers. The results of SEM and X-Ray diffraction confirmed the formation of β-Al{sub 9}FeMnSi and β-Al{sub 9}FeMn{sub 2}Si intermetallics in the substrate/coating interface as well as the presence of Cr and Ni, indicating diffusion of these two elements from the substrate to the interface. (Author)

Influence of the ion implantation on the nanoscale intermetallic phases formation in Ni-Ti system

International Nuclear Information System (INIS)

Kalashnikov, M.P.; Kurzina, I.A.; Bozhko, I.A.; Kozlov, E.V.; Fortuna, S.V.; Sivin, D.O.; Stepanov, I.B.; Sharkeev, Yu.P.

2005-01-01

Full text: The ion implantation at a high intensity mode is an effective method for modification of the surface properties of metals and alloys. Improvement of mechanical and tribological properties of irradiated materials using the high intensity implantation is connected with an element composition and microstructure modification of the surface and subsurface layers. One shows a great interest in intermetallic phase's synthesis by ion implantation, because of unique physical-mechanical properties of the intermetallic compounds. The influence of the irradiation conditions on the structural state and surface properties of implanted materials is not clear enough. The study of the factors influencing on the formation of the surface ion - alloyed layers of metal targets having the high tribological and mechanical properties by high intensity ion implantation is actual. The aim of the present work is a study of the microstructure, phase composition, physical and mechanical properties of the ion-alloyed Ni surfaces formed at high intensity implantation of Ti ions. The implantation Ti ions into Ni samples at high intensity mode was realized using ion source 'Raduga - 5'. The implantation Ti ions into Ni was carried out at accelerating voltage 20 kV for 2 h. The regimes were differed in the samples temperature (580 - 700 K), the distance from the ion implanted samples to the ion source (0.43-0.93 m) and the dose of irradiated ions (0.3·10 18 -2.9·10 18 ion/cm -2 ). The element composition of the implanted samples was analyzed by the electron spectroscopy. The structural-phase state of the Ni ion-modified layers was investigated by the transmission electron microscopy and X-ray diffraction methods. Additionally, the investigation of mechanical and tribological properties of the implanted Ni samples was carried out. It was established that the maximum thickness of the ion-alloyed nickel layers at high intensity mode allows forming the nanoscale intermetallic phases (Ni

Toughening and creep in multiphase intermetallics through ...

Indian Academy of Sciences (India)

It has however often been the case that the process of ductilisation or toughening has also led to a decrease in high temperature properties, especially creep. In this paper we describe approaches to the ductilisation of two different classes of intermetallic alloys through alloying to introduce beneficial, second phase effects.

The Effectiveness of Surface Coatings on Preventing Interfacial Reaction During Ultrasonic Welding of Aluminum to Magnesium

Science.gov (United States)

Panteli, Alexandria; Robson, Joseph D.; Chen, Ying-Chun; Prangnell, Philip B.

2013-12-01

High power ultrasonic spot welding (USW) is a solid-state joining process that is advantageous for welding difficult dissimilar material couples, like magnesium to aluminum. USW is also a useful technique for testing methods of controlling interfacial reaction in welding as the interface is not greatly displaced by the process. However, the high strain rate deformation in USW has been found to accelerate intermetallic compound (IMC) formation and a thick Al12Mg17 and Al3Mg2 reaction layer forms after relatively short welding times. In this work, we have investigated the potential of two approaches for reducing the IMC reaction rate in dissimilar Al-Mg ultrasonic welds, both involving coatings on the Mg sheet surface to (i) separate the join line from the weld interface, using a 100- μm-thick Al cold spray coating, and (ii) provide a diffusion barrier layer, using a thin manganese physical vapor deposition (PVD) coating. Both methods were found to reduce the level of reaction and increase the failure energy of the welds, but their effectiveness was limited due to issues with coating attachment and survivability during the welding cycle. The effect of the coatings on the joint's interface microstructure, and the fracture behavior have been investigated in detail. Kinetic modeling has been used to show that the benefit of the cold spray coating can be attributed to the reaction rate reverting to that expected under static conditions. This reduces the IMC growth rate by over 50 pct because at the weld line, the high strain rate dynamic deformation in USW normally enhances diffusion through the IMC layer. In comparison, the thin PVD barrier coating was found to rapidly break up early in USW and become dispersed throughout the deformation layer reducing its effectiveness.

Evaluation of the physicochemical and biopharmaceutical properties of fluoro-indomethacin.

Science.gov (United States)

Mori, Michela M; Airaksinen, Anu J; Hirvonen, Jouni T; Santos, Hélder A; Caramella, Carla M

2013-01-01

Drug nanocarriers have shown great potential in therapy and as diagnostic probes, e.g. in imaging of cancer and inflammation. Imaging can be applied to localize the carrier or the drug itself in the body and/or tissues. In this particular case it is important that drug molecules have the characteristics for possible detection, e.g. after modification with positron emission tomography compliant radioisotopes, without affecting their pharmacological behavior. In order to easily and efficiently follow the ADME profile of the drug after loaded into nanocarriers, the drug can be radiolabelled with, e.g. 18F-label, in order to assess its biodistribution after enteral and parenteral administration in rats. However, this is only possible if the derivative compound behaves similarly to the parent drug compound. In this study, indomethacin (a poorly water-soluble drug) was chosen as a model compound and aimed to evaluate the physicochemical and biopharmaceutical properties of an analog of indomethacin (IMC), fluoro-indomethacin (F-IMC). Although some of the physicochemical and biopharmaceutical properties of IMC are already known, in order to establish a feasible comparison between IMC and F-IMC, the behavior of the former was also investigated in the same conditions as for F-IMC. In this context, both IMC and F-IMC were thermally and morphologically studied. Furthermore, the following properties were also studied for both compounds: pKa and logP, solubility and dissolution profiles at physiological pH values, and toxicity at different concentrations in Caco-2 cells. Finally, the transport across Caco- 2 monolayers of the IMC and F-IMC at physiological pH range was also investigated. The results obtained showed similar values in pKalogP, solubility, dissolution, cytotoxicity, and permeability for both compounds. Thus, there might be strong evidence that both IMC and F-IMC should have a similar ADME behavior and profiles in vivo. The results provide fundamental tools and

Diffusion barrier characteristics and shear fracture behaviors of eutectic PbSn solder/electroless Co(W,P) samples

International Nuclear Information System (INIS)

Pan, Hung-Chun; Hsieh, Tsung-Eong

2012-01-01

Highlights: ► Diffusion barrier features, activation energies of IMC growth and mechanical behaviors of electroless Co(W,P)/PbSn joints. ► Amorphous Co(W,P) is a sacrificial- plus stuffed-type barrier while polycrystalline Co(W,P) is a sacrificial-type barrier. ► Ductile mode dominates the failure of Co(W,P)/PbSn joints. ► Phosphorus content of Co(W,P) is crucial to the barrier capability and microstructure evolution at Co(W,P)/PbSn interface. ► Diffusion barrier capability is governed by the nature of chemical bonds, rather than the crystallinity of materials. - Abstract: Diffusion barrier characteristics, activation energy (E a ) of IMC growth and bonding properties of amorphous and polycrystalline electroless Co(W,P) (termed as α-Co(W,P) and poly-Co(W,P)) to eutectic PbSn solder are presented. Intermetallic compound (IMC) spallation and an nano-crystalline P-rich layer were observed in PbSn/α-Co(W,P) samples subjected to liquid-state aging at 250 °C. In contrast, IMCs resided on the P-rich layer in PbSn/α-Co(W,P) samples subjected to solid-state aging at 150 °C. Thick IMCs neighboring to an amorphous W-rich layer was seen in PbSn/poly-Co(W,P) samples regardless of the aging type. α-Co(W,P) was found to be a sacrificial- plus stuffed-type barrier while poly-Co(W,P) is mainly a sacrificial-type barrier. The values of E a 's for PbSn/α-Co(W,P) and PbSn/poly-Co(W,P) systems were 338.6 and 167.5 kJ/mol, respectively. Shear test revealed the ductile mode dominates the failure in both α- and poly-Co(W,P) samples. Analytical results indicated the high P content in electroless layer might enhance the barrier capability but degrade the bonding strength.

EFFECT OF INTERMETALLIC PHASES ON CORROSION BEHAVIOR AND MECHANICAL PROPERTIES OF DUPLEX STAINLESS STEEL AND SUPER-DUPLEX STAINLESS STEEL

Directory of Open Access Journals (Sweden)

Prabhu Paulraj

2015-08-01

Full Text Available Duplex Stainless Steels (DSS and Super Duplex Stainless Steel (SDSS have excellent integration of mechanical and corrosion properties. However, the formation of intermetallic phases is a major problem in their usage. The mechanical and corrosion properties are deteriorated due to the presence of intermetallic phases. These phases are induced during welding, prolonged exposure to high temperatures, and improper heat treatments. The main emphasis of this review article is on intermetallic phases and their effects on corrosion and mechanical properties. First the effect of various alloying elements on DSS and SDSS has been discussed followed by formation of various intermetallic phases. The intermetallic phases affect impact toughness and corrosion resistance significantly. Their deleterious effect on weldments has also been reviewed.

Pressure-induced phenomena in U intermetallics

Czech Academy of Sciences Publication Activity Database

Sechovský, V.; Honda, F.; Prokeš, K.; Syshchenko, O.; Andreev, Alexander V.; Kamarád, Jiří

2003-01-01

Roč. 34, č. 2 (2003), s. 1377-1386 ISSN 0587-4254. [International Conference on Strongly Correlated Electron Systems (SCES 02). Cracow, 10.07.2002-13.07.2002] R&D Projects: GA ČR GA202/02/0739 Institutional research plan: CEZ:AV0Z1010914; CEZ:MSM 113200002 Keywords : pressure effect * intermetallics Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.752, year: 2003

Influence of Al grain boundaries segregations and La-doping on embrittlement of intermetallic NiAl

Energy Technology Data Exchange (ETDEWEB)

Kovalev, Anatoly I., E-mail: a_kovalev@sprg.ru; Wainstein, Dmitry L.; Rashkovskiy, Alexander Yu.

2015-11-01

Highlights: • We investigated Al grain boundaries segregations in ordered pure and La-doped NiAl. • Structural segregation of Al decreases critical strain for brittle cracks nucleation. • La alloying sharply improves plasticity of NiAl intermetallic. • Metallicity of interatomic bonds on grain boundaries increases at La alloying. • We have experimentally measured by EELFS that La atoms are located in Al sublattice. - Abstract: The microscopic nature of intergranular fracture of NiAl was experimentally investigated by the set of electron spectroscopy techniques. The paper demonstrates that embrittlement of NiAl intermetallic compound is caused by ordering of atomic structure that leads to formation of structural aluminum segregations at grain boundaries (GB). Such segregations contain high number of brittle covalent interatomic bonds. The alloying by La increases the ductility of material avoiding Al GB enrichment and disordering GB atomic structure. The influence of La alloying on NiAl mechanical properties was investigated. GB chemical composition, atomic and electronic structure transformations after La doping were investigated by AES, XPS and EELFS techniques. To qualify the interatomic bonds metallicity the Fermi level (E{sub F}) position and electrons density (n{sub eff}) in conduction band were determined in both undoped and doped NiAl. Basing on experimental results the physical model of GB brittleness formation was proposed.

Corrosion Study and Intermetallics Formation in Gold and Copper Wire Bonding in Microelectronics Packaging

Directory of Open Access Journals (Sweden)

Christopher Breach

2013-07-01

Full Text Available A comparison study on the reliability of gold (Au and copper (Cu wire bonding is conducted to determine their corrosion and oxidation behavior in different environmental conditions. The corrosion and oxidation behaviors of Au and Cu wire bonding are determined through soaking in sodium chloride (NaCl solution and high temperature storage (HTS at 175 °C, 200 °C and 225 °C. Galvanic corrosion is more intense in Cu wire bonding as compared to Au wire bonding in NaCl solution due to the minimal formation of intermetallics in the former. At all three HTS annealing temperatures, the rate of Cu-Al intermetallic formation is found to be three to five times slower than Au-Al intermetallics. The faster intermetallic growth rate and lower activation energy found in this work for both Au/Al and Cu/Al as compared to literature could be due to the thicker Al pad metallization which removed the rate-determining step in previous studies due to deficit in Al material.

Intermetallic nickel silicide nanocatalyst-A non-noble metal-based general hydrogenation catalyst.

Science.gov (United States)

Ryabchuk, Pavel; Agostini, Giovanni; Pohl, Marga-Martina; Lund, Henrik; Agapova, Anastasiya; Junge, Henrik; Junge, Kathrin; Beller, Matthias

2018-06-01

Hydrogenation reactions are essential processes in the chemical industry, giving access to a variety of valuable compounds including fine chemicals, agrochemicals, and pharmachemicals. On an industrial scale, hydrogenations are typically performed with precious metal catalysts or with base metal catalysts, such as Raney nickel, which requires special handling due to its pyrophoric nature. We report a stable and highly active intermetallic nickel silicide catalyst that can be used for hydrogenations of a wide range of unsaturated compounds. The catalyst is prepared via a straightforward procedure using SiO 2 as the silicon atom source. The process involves thermal reduction of Si-O bonds in the presence of Ni nanoparticles at temperatures below 1000°C. The presence of silicon as a secondary component in the nickel metal lattice plays the key role in its properties and is of crucial importance for improved catalytic activity. This novel catalyst allows for efficient reduction of nitroarenes, carbonyls, nitriles, N-containing heterocycles, and unsaturated carbon-carbon bonds. Moreover, the reported catalyst can be used for oxidation reactions in the presence of molecular oxygen and is capable of promoting acceptorless dehydrogenation of unsaturated N-containing heterocycles, opening avenues for H 2 storage in organic compounds. The generality of the nickel silicide catalyst is demonstrated in the hydrogenation of over a hundred of structurally diverse unsaturated compounds. The wide application scope and high catalytic activity of this novel catalyst make it a nice alternative to known general hydrogenation catalysts, such as Raney nickel and noble metal-based catalysts.

Magnetic properties of Nd3(Fe,Mo)29 compound and its nitride

International Nuclear Information System (INIS)

Pan Hongge

1998-01-01

The iron-rich ternary intermetallic compound Nd 3 (Fe,Mo) 29 with the Nd 3 (Fe,Ti) 29 -type monoclinic structure and its nitride were prepared. After nitrogenation, the nitride retains the structure of the parent compound, but the unit-cell volume of the nitride is 5.9% greater than that of the parent compound. The Curie temperature of Nd 3 (Fe,Mo) 29 nitride is 70.9% higher than that of the parent compound and the saturation magnetization of the nitride is about 6.6% (at 4.2 K) and 23.7% (at 300 K) higher than that of the parent compound. The anisotropy of the nitride is similar to that of parent compound, which exhibits plane anisotropy. (orig.)

Al and Si Alloying Effect on Solder Joint Reliability in Sn-0.5Cu for Automotive Electronics

Science.gov (United States)

Hong, Won Sik; Oh, Chulmin; Kim, Mi-Song; Lee, Young Woo; Kim, Hui Joong; Hong, Sung Jae; Moon, Jeong Tak

2016-12-01

To suppress the bonding strength degradation of solder joints in automotive electronics, we proposed a mid-temperature quaternary Pb-free Sn-0.5Cu solder alloy with minor Pd, Al, Si and Ge alloying elements. We manufactured powders and solder pastes of Sn-0.5Cu-(0.01,0.03)Al-0.005Si-(0.006-0.007)Ge alloys ( T m = 230°C), and vehicle electronic control units used for a flame-retardant-4 printed circuit board with an organic solderability preservative finish were assembled by a reflow soldering process. To investigate the degradation properties of solder joints used in engine compartments, thermal cycling tests were conducted from -40°C to 125°C (10 min dwell) for 1500 cycles. We also measured the shear strength of the solder joints in various components and observed the microstructural evolution of the solder joints. Based on these results, intermetallic compound (IMC) growth at the solder joints was suppressed by minor Pd, Al and Si additions to the Sn-0.5Cu alloy. After 1500 thermal cycles, IMC layers thicknesses for 100 parts per million (ppm) and 300 ppm Al alloy additions were 6.7 μm and 10 μm, compared to the as-reflowed bonding thicknesses of 6 μm and 7 μm, respectively. Furthermore, shear strength degradation rates for 100 ppm and 300 ppm Al(Si) alloy additions were at least 19.5%-26.2%. The cause of the improvement in thermal cycling reliability was analyzed using the (Al,Cu)-Sn, Si-Sn and Al-Sn phases dispersed around the Cu6Sn5 intermetallic at the solder matrix and bonding interfaces. From these results, we propose the possibility of a mid-temperature Sn-0.5Cu(Pd)-Al(Si)-Ge Pb-free solder for automotive engine compartment electronics.

Superconducting transition temperature and the formation of closed electron shells in the atoms of superconducting compounds

International Nuclear Information System (INIS)

Chapnik, I.M.

1985-01-01

The relationship between the regularities in the tansition temperature (T/sub c/) values in analogous compounds (having the same structure and stoichiometry) and the formation of the closed electron shells outside inert gas shells in the atoms of the variable component of the 158 intermetallic superconducting compounds has been discussed. The T/sub c/ data for compounds of the elements from the first long period of the Periodic Table (K to Se) are compared with the T/sub c/ data for the analogous compounds of the elements from the second long period (Rb to Te)

Effect of P on Microstructure and Mechanical Properties of Sn-Bi Solder

Directory of Open Access Journals (Sweden)

WANG Xiao-jing

2016-07-01

Full Text Available Micro alloy metals P or P/Cu/Zn were added into Sn-Bi alloy to investigate the doping effects on microstructure, mechanical property, deformation fracture from the function of P in pure tin. The results show that doping 1%( mass fraction, same as below P to pure tin can improve the strength and stiffness, decrease the plasticity. Only 0.1%P additive degenerates the mechanical property of Sn-Bi alloy, this is related to the existing form of element P in the base metal and the microstructure of the base metal. In Sn base alloy, P is distributed in phase or grain boundaries in the form of Sn-P intermetallic compounds (IMC, restricting the diffusion and shifting of deformation. Therefore, Sn-1P alloy, IMC distributed in beta-tin base plays a role of strengthening in pure tin doped situation, in Sn-Bi alloy instead, enhancing the deformation mismatch under loading becoming the weak spots where cracks may initiate and propagate, and leading to brittle fracture . Finally, addition of P/Zn/Cu simultaneously to Sn-Bi alloy, the doping can optimize the microstructure, improve the strength and enhance the ultimate tensile strength (UTS of Sn-Bi alloys.

Microstructure and mechanical properties of resistance-spot-welded joints for A5052 aluminum alloy and DP 600 steel

Energy Technology Data Exchange (ETDEWEB)

Chen, Jianbin [College of Automotive Collaborative Innovation Center, Chongqing University, No. 174, Shazheng Street, Shapingba District, Chongqing 400044 (China); Yuan, Xinjian, E-mail: xinjianyuan@yahoo.com [College of Materials Science and Engineering, Chongqing University, No. 174, Shazheng Street, Shapingba District, Chongqing 400044 (China); Hu, Zhan; Sun, Changzheng; Zhang, Yanxin; Zhang, Yuxuan [College of Materials Science and Engineering, Chongqing University, No. 174, Shazheng Street, Shapingba District, Chongqing 400044 (China)

2016-10-15

The microstructure and mechanical properties of resistance-spot-welded A5052 aluminum alloy and DP 600 dual-phase steel joint were studied. The fusion zone (FZ) and heat-affected zone (HAZ) of DP 600 exhibited lath martensite and ferrite-martensite structures, respectively. The microstructure of FZ and HAZ in the A5052 side was composed of cellular crystals and the boundary region of FZ exhibited a columnar crystal morphology. A Fe{sub 2}Al{sub 5} intermetallic compound (IMC) layer with 3.3 μm thickness was found adjacent to the DP 600 side, whereas a needle-shaped Fe{sub 4}Al{sub 13} IMC layer with length of 0.67 μm to 15.8 μm was found adjacent to the aluminum alloy side. The maximum tensile shear load of the A5052/DP 600 joint was 5.5 KN, with a corresponding molten nugget diameter of 6.3 mm. The fracture morphology of the optimized A5052/DP 600 joint was mainly an elongated dimple fracture accompanied by cleavage fracture. - Highlights: •A5052 and DP 600 with large gaps in properties were investigated by RSW. •The microstructures of RSW joints in DP 600/A5052 were examined detailedly. •The micro/macro-characteristics and strength relations of joints were analyzed.

Evaluation on the characteristics of tin-silver-bismuth solder

Science.gov (United States)

Xia, Z.; Shi, Y.; Chen, Z.

2002-02-01

Tin-silver-bismuth solder is characterized by its lower melting point, good wetting behavior, and good mechanical property for which it is expected to be a new lead-free solder to replace tin-lead solder. In this article, Sn-3.33Ag-4.83Bi solder was investigated concerning its physical, spreading, and mechanical properties under specific conditions. Cooling curves and DSC results showed that it was close to eutectic composition (m.p. 210° 212 °C). Coefficiency of thermal expansion (CTE) of this solder, between that of PCBs and copper substrates, was beneficial to alleviate the thermal mismatch of the substrates. It was also a good electrical and thermal conductor. Using a rosin-based, mildly activated (RMA) flux, a spreading test indicated that SnAgBi solder paste had good solderability. Meanwhile, the solder had high tensile strength and fracture energy. Its fracture mechanism was a mixture of ductile and brittle fracture morphology. The metallographic and EDAX analyses indicated that it was composed of a tin-based solid solution and some intermetallic compound (IMC) that could strengthen the substrate. However, these large needle-like IMCs would cut the substrate and this resulted in the decreasing of the toughness of the solder.

Composites having an intermetallic containing matrix

International Nuclear Information System (INIS)

Nagle, D.C.; Brupbacher, J.M.; Christodoulou, L.

1990-01-01

This paper describes a composite material. It comprises: a dispersion of in-situ precipitated second phase particles selected from the group consisting of borides, carbides, nitrides, and sulfides, in an intermetallic containing matrix selected from the group consisting of the aluminides, silicides, and beryllides of nickel, copper, titanium, cobalt, iron, platinum, gold, silver, niobium, tantalum, zinc, molybdenum, hafnium, tin, tungsten, lithium, magnesium, thorium, chromium, vanadium, zirconium, and manganese

Size and surface AREA analysis of some metallic and intermetallic powders

International Nuclear Information System (INIS)

Elmasry, M.A.A.; Elsayed, A.A.; Abadir, M.F.

1988-01-01

The powder characterization of three intermetallic compounds ( Cr B, B 4 c and S ib 4 ) and three metallic powders (Fe, Co, and Ni) has been performed. This included the determination of powder density, chemical analysis, impurity analysis, shape factor, particle size analysis and specific surface area. The particle size analysis for the six powders was carried out using three techniques, namely; the 0-23, the microtrac and the fisher sub sieve and size. It was found that the analysis of the two powders and deviates from the log-normal probability distribution and the deviation was corrected. The specific surface area of the powders was measured using the high speed surface area analysis (BET method), and it was also calculated from surface area analysis findings, the BET technique was found to give the highest specific surface area values, and was attributed to the inclusion of internal porosity in the measurement. 8 fig., 10 tab

Mechanical Deformation Behavior of Sn-Ag-Cu Solders with Minor Addition of 0.05 wt.% Ni

Science.gov (United States)

Hammad, A. E.; El-Taher, A. M.

2014-11-01

The aim of the present work is to develop a comparative evaluation of the microstructural and mechanical deformation behavior of Sn-Ag-Cu (SAC) solders with the minor addition of 0.05 wt.% Ni. Test results showed that, by adding 0.05Ni element into SAC solders, generated mainly small rod-shaped (Cu,Ni)6Sn5 intermetallic compounds (IMCs) inside the β-Sn phase. Moreover, increasing the Ag content and adding Ni could result in the change of the shape and size of the IMC precipitate. Hence, a significant improvement is observed in the mechanical properties of SAC solders with increasing Ag content and Ni addition. On the other hand, the tensile results of Ni-doped SAC solders showed that both the yield stress and ultimate tensile strengths decrease with increasing temperature and with decreasing strain rate. This behavior was attributed to the competing effects of work hardening and dynamic recovery processes. The Sn-2.0Ag-0.5Cu-0.05Ni solder displayed the highest mechanical properties due to the formation of hard (Cu,Ni)6Sn5 IMCs. Based on the obtained stress exponents and activation energies, it is suggested that the dominant deformation mechanism in SAC (205)-, SAC (0505)- and SAC (0505)-0.05Ni solders is pipe diffusion, and lattice self-diffusion in SAC (205)-0.05Ni solder. In view of these results, the Sn-2.0Ag-0.5Cu-0.05Ni alloy is a more reliable solder alloy with improved properties compared with other solder alloys tested in the present work.

Phase transition of intermetallic TbPt at high temperature and high pressure

Science.gov (United States)

Qin, Fei; Wu, Xiang; Yang, Ke; Qin, Shan

2018-04-01

Here we present synchrotron-based x-ray diffraction experiments combined with diamond anvil cell and laser heating techniques on the intermetallic rare earth compound TbPt (Pnma and Z  =  4) up to 32.5 GPa and ~1800 K. The lattice parameters of TbPt exhibit continuous compression behavior up to 18.2 GPa without any evidence of phase transformation. Pressure-volume data were fitted to a third-order Birch-Murnaghan equation of state with V 0  =  175.5(2) Å3, {{K}{{T0}}}   =  110(5) GPa and K{{T0}}\\prime   =  3.8(7). TbPt exhibits anisotropic compression with β a   >  β b   >  β c and the ratio of axial compressibility is 2.50:1.26:1.00. A new monoclinic phase of TbPt assigned to the Pc or P2/c space group was observed at 32.5 GPa after laser heating at ~1800 K. This new phase is stable at high pressure and presented a quenchable property on decompression to ambient conditions. The pressure-volume relationship is well described by the second-order Birch-Murnaghan equation of state, which yields V 0  =  672(4) Å3, {{K}{{T0}}}   =  123(6) GPa, which is about ~14% more compressible than the orthorhombic TbPt. Our results provide more information on the structure and elastic property view, and thus a better understanding of the physical properties related to magnetic structure in some intermetallic rare earth alloys.

Effects of Nb content on the Zr{sub 2}Fe intermetallic stability

Energy Technology Data Exchange (ETDEWEB)

Ramos, C. E-mail: ciramos@cnea.gov.ar; Saragovi, C.; Granovsky, M.; Arias, D

2003-02-01

With the aim of studying the stability range of the Zr{sub 2}Fe intermetallic when adding Nb, the range of existence of the cubic ternary phase ({lambda}{sub 1}) and the corresponding two-phase field between them, four samples were analyzed, each one containing 35 at.% Fe and different at.% Nb: 0.5, 4 10 and 15. Optical and scanning electron metallographies, X-ray diffraction, microprobe analysis and Moessbauer spectroscopy were performed to determine and characterize the phases present in the samples. Results show that the Zr{sub 2}Fe compound accepts up to nearly 0.5 at.% Nb in solution, since the Zr{sub 2}Fe+{lambda}{sub 1} region is stable in the (0.5-3.5) at.% Nb range. To summarize these results an 800 deg. C section of the ternary Zr-Nb-Fe diagram, in the studied zone, was proposed.

3D study of intermetallics and their effect on the corrosion morphology of rheocast aluminium alloy

International Nuclear Information System (INIS)

Mingo, B.; Arrabal, R.; Pardo, A.; Matykina, E.; Skeldon, P.

2016-01-01

In the present study, the effect of heat treatment T6.1 on the microstructure and corrosion behaviour of rheocast aluminium alloy A356 is investigated on the basis of 2D/3D characterization techniques and electrochemical and SKPFM measurements. Heat treatment strengthens the α-Al matrix, modifies the intermetallic particles and spheroidizes eutectic Si. These changes do not modify significantly the corrosion behaviour of the alloy. 3D SEM-Tomography clearly shows that the corrosion advances in the shape of narrow paths between closely spaced intermetallics without a major influence of eutectic Si. - Highlights: • T6.1 spheroidizes Si, strengthens the matrix and modifies the intermetallics. • Electrochemical behaviour of untreated and heat-treated alloys is similar. • 3D SEM-Tomography provides additional information on the corrosion morphology. • Corrosion advances as paths between intermetallics with little influence of Si.

Intermetallics: past, present and future

Directory of Open Access Journals (Sweden)

Morris, D. G.

2005-12-01

Full Text Available Intermetallics have seen extensive world-wide attention over the past decades. For the most part these studies have examined multi-phase aluminide based alloys, because of their high stiffness, combined with reasonable strength and ductility, good structural stability and oxidation resistance, and attempted to improve current Ni-base superalloys, Ti-base alloys, or Fe-base stainless steels for structural aerospace applications. The current status of development and application of such materials is briefly reviewed. Future developments are taking intermetallics from the realm of "improved high-temperature but low-ductility metallic alloys" into the realm of "improved aggressive-environment, high-toughness ceramic-like alloys". Such evolution will be outlined.

Durante los últimos décadas ha habido un desarrollo de los intermetálicos, sobre todo por aplicaciones estructurales a alta temperatura en aplicaciones aeroespaciales, donde, por su rigidez alta, en combinación con una resistencia mecánica y ductilidad razonable, su buena estabilidad estructural y resistencia a la oxidación, han sido vistos como versiones avanzadas y mejoradas de las aleaciones metálicas como, por ejemplo, las superaleaciones a base de nitrógeno y las aleaciones de titanio. Se discute el desarrollo importante durante las últimas décadas, y también los nuevos desarrollos probables durante los próximos años. Se podrían ver los intermetálicos como versiones mejoradas de los cerámicos.

Development of intermetallic coatings for fusion power applications

International Nuclear Information System (INIS)

Park, J.H.; Domenico, T.; Dragel, G.; Clark, R.

1994-03-01

In the design of liquid-metal cooling systems, corrosion resistance of structural materials and magnetohydrodynamic (MHD) force and its subsequent influence on thermal hydraulics and corrosion are major concerns. The objective of this study is to develop stable corrosion-resistant electrical insulator coatings at the liquid-metal/structural-material interface, with emphasis on electrically insulating coatings that prevent adverse MHD-generated currents from passing through the structural walls. Vanadium and V-base alloys are potential materials for structural applications in a fusion reactor. Insulator coatings inside the tubing are required when the system is cooled by liquid metals. Various intermetallic films were produced on V, V-t, and V-20 Ti, V-5Cr-t and V-15Cr-t, and Ti, and Types 304 and 316 stainless steel. The intermetallic layers were developed by exposure of the materials to liquid lithium of 3--5 at.% and containing dissolved metallic solutes at temperatures of 416--880 degrees C. Subsequently, electrical insulator coatings were produced by reaction of the reactive layers with dissolved nitrogen in liquid lithium or by air oxidation under controlled conditions at 600--1000 degrees C. These reactions converted the intermetallic layers to electrically insulating oxide/nitride or oxy-nitride layers. This coating method could be applied to a commercial product. The liquid metal can be used over and over because only the solutes are consumed within the liquid metal. The technique can be applied to various shapes because the coating is formed by liquid-phase reaction. This paper will discuss initial results on the nature of the coatings and their in-situ electrical resistivity characteristics in liquid lithium at high temperatures

Effect of Sr and solidification conditions on characteristics of intermetallic in Al-Si 319 industrial alloys

International Nuclear Information System (INIS)

Espinoza-Cuadra, J.; Gallegos-Acevedo, P.; Mancha-Molinar, H.; Picado, A.

2010-01-01

An experimental study was carried out to determine the effect of strontium (Sr) on the characteristic of intermetallic phases, particularly the Al 5 FeSi phase which present morphology of platelets or needle-like. The results showed that within the range of variables studied, the modification process caused the disappearance of the needles and only occur the precipitation of phase α (chinese script-like). Refinement of the intermetallic phases occurs in conjunction with the refinement in grain size. Both parameters depend strongly on local cooling rate (T), temperature gradient (G) and apparent rate of solidification front (V). In the case of equiaxed structures the refinement of grain size and intermetallic occurs with increasing local cooling rate and temperature gradient and decrease the apparent rate of solidification front. In the case of columnar structures, refinement of grains and intermetallic requires the increase in values of the three variables indicated. Moreover, the addition of Sr resulted in the modification of silicon eutectic, as noted in others research works.

Integrated Marketing Communications (IMC) Variables That Influence Perceived Return on Investment (ROI) in Higher Education: Chief Marketing Officers' Perceptions

Science.gov (United States)

King, Adrienne L.

2013-01-01

This study examines the relationship of the level of Integrated Marketing Communications (IMC) implementation, level of open systems and change in state appropriations on perceived return on investment (ROI) in U.S. public higher education institutions (HEIs). Designed to provide HEI leaders with data to more accurately determine the best IMC…

Lattice disorder in strongly correlated lanthanide and actinide intermetallics

International Nuclear Information System (INIS)

Booth, C.H.; Bauer, E.D.; Maple, M.B.; Lawrence, J.M.; Kwei, G.H.; Sarrao, J.L.

2001-01-01

Lanthanide and actinide intermetallic compounds display a wide range of correlated-electron behavior, including ferromagnetism, antiferromagnetism, nonmagnetic (Kondo) ground states, and so-called 'non-Fermi liquid' (NFL) behavior. The interaction between f electrons and the conduction band is a dominant factor in determining the ground state of a given system. However, lattice disorder can create a distribution of interactions, generating unusual physical properties. These properties may include NFL behavior in many materials. In addition, lattice disorder can cause deviations from standard Kondo behavior that is less severe than NFL behavior. A review of the lattice disorder mechanism within a tight-binding model is presented, along with measurements of the YbBCu 4 and UPd x Cu 5-x systems, demonstrating the applicability of the model. These measurements indicate that while the YbBCu 4 system appears to be well ordered, both site interchange and continuous bond-length disorder occur in the UPd x Cu 5-x series. Nevertheless, the measured bond-length disorder in UPdCu 4 does not appear to be enough to explain the NFL properties simply with the Kondo disorder model. (au)

Ab initio study of antiphase boundaries and stacking faults in L12 and DO22 compounds

DEFF Research Database (Denmark)

Rosengaard, N. M.; Skriver, Hans Lomholt

1994-01-01

We have performed ab initio calculations of the energies of antiphase boundaries as well as complex and superlattice intrinsic stacking faults in nine intermetallic compounds observed in the face-centered-cubic L1(2) and DO22 structures. The calculations were performed by means of a Green...

The sequence of intermetallic formation and solidification pathway of an Al–13Mg–7Si–2Cu in-situ composite