Sintering mechanism of Cu-9Al alloy prepared from elemental powders

• Main Authors: Zhenghua Deng, Haiqing Yin, Cong Zhang, Guofei Zhang, Tong Zhang, ZiKui Liu, Haibao Wang, Xuanhui Qu
• Format: Article
• Language: English
• Published: Elsevier 2019-08-01
• Series: Progress in Natural Science: Materials International
• Online Access: http://www.sciencedirect.com/science/article/pii/S1002007118308694

The sintering behavior of Cu-9Al alloys prepared from die pressing of elemental powders was investigated. The experimental results and kinetic analysis showed the formation of three consecutive layers of Al2Cu, Al4Cu9, and AlCu phases, with Al2Cu appearing first in the initial solid phase sintering stage. A liquid phase formed in the intermediate stage, resulting from the eutectic reaction between Al and Al2Cu phases at 500 °C, which is 47 °C lower than the equilibrium reaction temperature. Swelling occurred when the liquid phase infiltrated the gaps between the copper particles, leaving pores at the original sites of Al particles and Al2Cu. In the final stage of sintering, the Al-rich phases (Al2Cu and AlCu) transformed to Al-poor phases (Al4Cu9 and α-Cu) in the temperature range of 500–565 °C. Al4Cu9 and α-Cu then transformed to AlCu3 (β) above the eutectoid reaction temperature (565 °C), whereas AlCu3 transformed to α-Cu and eutectoid phases (α-Cu + Al4Cu9) during cooling. The pure copper transformed to AlCu3, and the pore volume decreased at 1000 °C. The microstructure study helps manipulate precisely the sintering process of Cu-Al alloys and optimize the microstructure with a high dimensional accuracy. Keywords: Cu-9Al alloy, Liquid phase sintering, Swelling behavior, Diffusion