The Thermal Conductivity of Ti-5Al-2.5 Sn between 1.2 and 35 K: The Effect of Plastic Deformation

1983 ◽  
pp. 7-13 ◽  
Author(s):  
Gary R. Austin ◽  
T. K. Chu ◽  
D. H. Damon
Keyword(s):  
Thermal Conductivity ◽  
Plastic Deformation

Lead-Free Alternatives for Interconnects in High-Temperature Electronics

2017 ◽  
Author(s):  
Sandeep Mallampati ◽  
Liang Yin ◽  
David Shaddock ◽  
Harry Schoeller ◽  
Junghyun Cho
Keyword(s):  
Thermal Conductivity ◽  
Plastic Deformation ◽  
Shear Strength ◽  
High Temperature ◽  
Heat Dissipation ◽  
Volume Fraction ◽  
High Volume ◽  
Die Attach ◽  
Average Shear Strength ◽  
Average Shear

Predominant high melting point solders for high temperature and harsh environment electronics (operating temperatures from 200 to 250°C) are Pb-based systems, which are being subjected to RoHS regulations because of their toxic nature. In this study, high bismuth (Bi) alloy compositions with Bi-XSb-10Cu (X from 10 wt.% to 20 wt.%) were designed and developed to evaluate their potential as high-temperature, Pb-free replacements. Reflow processes were developed to make die-attach samples made out of the cast Bi alloys. In particular, die-attach joints made out of Bi-15Sb-10Cu alloy exhibited an average shear strength of 24 MPa, which is comparable to that of commercially available high Pb solders. These alloy compositions also retained original shear strength even after thermal shock between −55°C and +200°C and high temperature storage at 200°C. Brittle interfacial fracture sometimes occurred along the interfacial NiSb layer formed between Bi(Sb) matrix and Ni metallized surface. In addition, heat dissipation capabilities, using flash diffusivity, were measured on the die-attach assembly, compared to the corresponding bulk alloys. The thermal conductivity of all the Bi-Sb alloys was higher than that of pure Bi. By creating high volume fraction of precipitates in a die-attach joint microstructure, it was feasible to further increase thermal conductivity of this joint to 24 W/m·K, which is three times higher than that of pure Bi (8 W/m·K). Bi-15Sb-10Cu alloy has so far shown the most promising performance as a die-attach material for high temperature applications (operated over 200°C). Hence, this alloy was further studied to evaluate its potential for plastic deformation. Bi-15Sb-10Cu alloy has shown limited plastic deformation in room temperature tensile testing, in which premature fracture occurred via the cracks propagated on the (111) cleavage planes of rhombohedral crystal structure of the Bi(Sb) matrix. The same alloy has, however, shown up to 7% plastic strain under tension when tested at 175°C. The cleavage planes, which became oriented at smaller angles to the tensile stress, contributed to improved plasticity in the high temperature test.

Effect of Plastic Deformation on the Thermal Conductivity of Bismuth Crystals

1976 ◽  
Vol 41 (5) ◽  
pp. 1692-1698 ◽  
Author(s):  
Toru Matsuo ◽  
Hideji Suzuki
Keyword(s):  
Thermal Conductivity ◽  
Plastic Deformation

scholarly journals The influence of utrafine-grained state on thermo-physical properties of Zr-1 wt.% Nb and Ti-45 wt.% Nb alloys and processes of dissipation and accumulation of energy during deformation

2020 ◽  
pp. 28-35
Author(s):  
E.V. Legostaeva ◽  
◽  
Yu.P. Sharkeev ◽  
O.A. Belyavskaya ◽  
V.P. Vavilov ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Plastic Deformation ◽  
Heat Capacity ◽  
Physical Properties ◽  
Specific Heat ◽  
Specific Heat Capacity ◽  
Coarse Grained ◽  
Ultrafine Grained ◽  
Substructural Hardening ◽  
Thermo Physical Properties

The results of studying the thermal conductivity and specific heat capacity of Zr-1 wt.% Nb and Ti-45 wt.% Nb in coarse-grained and ultrafine-grained states are presented. The influence of the utrafine-grained state on the thermo physical properties and the processes of dissipation and accumulation energy during deformation of the alloys are estimated. It is shown that formation of the ultrafine-grained state in the Zr-1 wt.% Nb alloy by abc -pressing and subsequent rolling leads to a decrease in its thermal conductivity and specific heat capacity by 10 and 20%, respectively, due to substructural hardening under severe plastic deformation. It is found that thermal conductivity and specific heat capacity of the ultrafine Ti-45 wt.% Nb alloy increase by 7.5 and 5%, respectively, due to dispersion hardening of the ω phase by nanoparticles and formation of a new α phase. It is established that the ultrafine-grained structure has a significant influence on the regularities of the dissipation and accumulation energy during plastic deformation, which in turn depend on their thermo-physical characteristics and on the structural and phase state.

Lead-Free Alternatives for Interconnects in High-Temperature Electronics

2018 ◽  
Vol 140 (1) ◽  
Author(s):  
Sandeep Mallampati ◽  
Liang Yin ◽  
David Shaddock ◽  
Harry Schoeller ◽  
Junghyun Cho
Keyword(s):  
Thermal Conductivity ◽  
Plastic Deformation ◽  
Shear Strength ◽  
High Temperature ◽  
Heat Dissipation ◽  
Volume Fraction ◽  
High Volume ◽  
Die Attach ◽  
Average Shear Strength ◽  
Average Shear

Predominant high melting point solders for high-temperature and harsh environment electronics (operating temperatures from 200 to 250 °C) are Pb-based systems, which are being subjected to RoHS regulations because of their toxic nature. In this study, high bismuth (Bi) alloy compositions with Bi-XSb-10Cu (X from 10 wt % to 20 wt %) were designed and developed to evaluate their potential as high-temperature, Pb-free replacements. Reflow processes were developed to make die-attach samples made from the cast Bi alloys. Die-attach joints made from Bi-15Sb-10Cu alloy exhibited an average shear strength of 24 MPa, which is comparable to that of commercially available high Pb solders. These alloy compositions also retained original shear strength even after thermal shock (TS) between −55 °C and +200 °C and high-temperature storage (HTS) at 200 °C. Brittle interfacial fracture sometimes occurred along the interfacial NiSb layer formed between Bi(Sb) matrix and Ni metallized surface. In addition, heat dissipation capabilities, using flash diffusivity, were measured on the die-attach assembly and were compared to the corresponding bulk alloys. The thermal conductivity of all the Bi–Sb alloys was higher than that of pure Bi. By creating high volume fraction of precipitates in a die-attach joint microstructure, it was feasible to further increase thermal conductivity of this joint to 24 W/m·K, which is three times higher than that of pure Bi (8 W/m·K). Bi–15Sb–10Cu alloy has so far shown the most promising performance as a die-attach material for high-temperature applications (operated over 200 °C). Hence, this alloy was further studied to evaluate its potential for plastic deformation. Bi–15Sb–10Cu alloy has shown limited plastic deformation in room temperature tensile testing in which premature fracture occurred via the cracks propagated on the (111) cleavage planes of rhombohedral crystal structure of the Bi(Sb) matrix. The same alloy has, however, shown up to 7% plastic strain under tension when tested at 175 °C. The cleavage planes, which became oriented at smaller angles to the tensile stress, contributed to improved plasticity in the high-temperature test.

Effect of plastic deformation on phonon thermal conductivity of α-Ag2S

2020 ◽  
Vol 117 (25) ◽  
pp. 253901
Author(s):  
Xin Liang ◽  
Chuang Chen ◽  
Feihu Dai
Keyword(s):  
Thermal Conductivity ◽  
Plastic Deformation ◽  
Phonon Thermal Conductivity
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