Clarification of the solid-state diffusion behavior of a copper alloy/aluminum alloy composite interface assisted by position marking of the second phases

Abstract

This paper studied the solid-state diffusion behavior of a C70250 copper alloy/8030 aluminum alloy composite interface. The formation sequence, growth direction and formation mechanism of the intermetallic compound (IMC) layers were clarified with the help of second phases and intensive microstructure characterization. The formation sequence of IMC layers at the composite interface is as follows: Al 2 Cu layer, AlCu layer with coarse grains, Al 4 Cu 9 layer, AlCu layer with fine grains, and (Cu,Ni) 5 Si layer. The spatial distribution of IMC layers at the composite interface is as follows: the Cu alloy, the (Cu,Ni) 5 Si layer, the Al 4 Cu 9 layer, the AlCu layer with fine grains, the AlCu layer with coarse grains, the Al 2 Cu layer, and the Al alloy. The Al 2 Cu layer and AlCu layer with coarse grains grow from the original composite interface to the Al alloy side, while the Al 4 Cu 9 layer and AlCu layer with fine grains grow from the original composite interface to the Cu alloy side. Moreover, with Al atoms diffusing toward the Cu alloy side, partial Ni atoms are combined with Al atoms to form the NiAl phase in the Al 4 Cu 9 layer and AlCu layer with fine grains. • The formation sequence of IMCs layers at the composite interface is clarified. • The growth direction of IMCs layers at the composite interface is clarified. • The positional relationship between IMCs layers and the original interface before heating is confirmed.