High Strength, High Electrical Conductivity Press-and-sinter Cu Alloys
Date Issued
2011
Date
2011
Author(s)
Liang, Yu-Ming
Abstract
As the electronic devices become lighter and smaller, thermal management becomes a big issue. Since copper and copper alloys have high thermal conductivities, these materials have been widely used in these electronic devices. However, copper is soft after sintering, which limits its applications. To solve this problem, methods of grain refinement, precipitation hardening, and dispersion strengthening were used in this study to improve the strength and hardness of press-and-sintered copper alloys without losing much of the electrical and thermal conductivities.
Results shows that sintering fine (D50 = 5μm) copper powder at 800℃ for 3 hrs in hydrogen can reach 97% relative density, HV 51 hardness, and 100 IACS% electrical conductivity. For precipitation hardening alloys, copper-0.7 wt% chromium alloys were sintered and solution treated at 1050℃ for 3 hrs in hydrogen. After water quenching and aging at 450℃ for 3 hrs in hydrogen, a hardness of HV 109 and an electrical conductivity of 86 IACS% were obtained. Deforming specimens before aging further increased the hardness to HV 152 and the electrical conductivity slightly increased to 89 IACS%. For dispersion strengthening alloys, wet mixing and high energy milling were used in order to attain uniform distribution of dispersed particles in the copper matrix. Copper-0.2 vol% tungsten alloy sintered at 950℃ for 3 hrs reached HV 57 hardness and 99 IACS% electrical conductivity. Copper-4.83 vol% alumina (1 wt% aluminum) alloy was internal oxidize at 700℃ and sintered at 1050℃ for 3 hrs, and the hardness and electrical conductivity reached HV 192 and 67 IACS%, respectively. Copper-1 vol% alumina (0.2 wt% aluminum) alloys sintered at 950℃ for 3 hrs showed 97% relative density, HV 178 hardness, and 76 IACS% electrical conductivity. Copper-0.5 vol% alumina (0.1 wt% aluminum) alloys sintered at 900℃ for 3 hrs exhibit 99% relative density, HV 170 hardness, and 78 IACS% electrical conductivity.
Subjects
Powder metallurgy
grain refinement
precipitation hardening, dispersion strengthening
high energy milling
internal oxidation
Type
thesis
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