Abstract
A mechanofusion apparatus which can operate at a high vacuum pressure of the order of 10-2 Pa was developed. Using this apparatus, formation of Cu composite with Al2O3 core particles was conducted. The rate of progress of composite formation was low under atmospheric or low vacuum conditions but under a high vacuum or in an Ar displaced atmosphere, such formation was remarkably accelerated. Namely, it was found that composite formation is greatly accelerated by lowering the oxygen partial pressure. Following oxygen analysis of the Cu covering layer of composite particles by AES, it was found that with a higher atmospheric pressure, the oxygen amount became higher and oxygen penetrated into the interior.
As a result of microstructure observations of the composite particles to which extended mechanofusion processing and chemical etching had been applied, grain boundaries were observed in the Cu covering layer which may imply that the Cu particle surface becomes exposed to high temperature as more sintering occurs. This microstructure is very similar to the structure of Cu after high temperature annealing. The individual particle surface temperatures during mechanofusion was estimated as being around 1000 K from the experimental results of sintering behavior of cold pressed Cu.
† This report was originally printed in Journal of the Japan Society of Powder and Powder Metallurgy, 39(12), 1124-1128, 1129-1133 (1992) in Japanese, before being translated into English by KONA Editorial Committee with the permission of the editorial committee of Japan Society of Powder and Powder Metallurgy.
