アルミニウム青銅系混合圧粉体の焼結に関する研究

概要

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In this experiment it was confirmed that Cu-Al binary mixed compacts were abruptly expanded at the eutectic temperature of 548°C on heating by the exothermic reaction of γ2(Cu9Al4)-formation, and this volume expansion disturbed the following sintering of the compacts. In order to evade the exothermic reaction above described 50 wt% Cu-50 wt% γ2 pseudobinarv mixed compacts were examined. However, they were also expanded on heating above 600°C by the Kirkendall diffusion (voidformation), and then the influence of Mn, Fe and Ni as an alloying element respectively on the expansion of the pseudobinary compacts were investigated. Results obtained are as follows: The expansion of the compact was increased by Mn-addition, but decreased by Fe-and Ni-addition, where the effect of Ni was superior to Fe far beyond comparison. Since Ni has the tendency to diffuse selectively in the γ2 phase, difference of intrinsic diffusivities between Cu and Al in the mixed compact seems to be reduced by the selective diffusion of Ni. When Ni-coated Cu particles were combined with the same quantity of γ2 particles, diffusion of Ni should be made easier in the Cu-Ni-γ2 pseudoternary mixed compact, therefore the compact. did not expand abnormally on heating. Consequently the sintered aluminium-bronze of high density could be obtained from the mixed compact of Ni-coated Cu particles and γ2 particles.
社団法人粉体粉末冶金協会の論文