メッキ粉末を用いたFe-Ni-P圧粉体の焼結過程

概要

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Sintering behavior of Fe-Ni-P compacts prepared by electroless plating on iron powder was studied by means of dilatometric method and electron probe micro analysis. The sintering of Fe-Ni-P plated powder compacts containing phosphorous in the plated layer more than the eutectic composition of Ni-P alloy was enhanced compared with the case of Fe-Ni plated powder compacts. The following mechanism was proposed for the enhanced sintering in the compacts of Fe-Ni-P plated powder: During heating up to about 1123K, stable Ni-P alloyed layer exists between iron particles, and enhanced interdiffusion of nickel and phosphorous, caused by lowering the liquidus temperature with increasing phosphorous content of Ni-P alloy, promotes the sintering of Fe-Ni-P compacts. Also, during heating from the temperature range above the Ac<SUB>3</SUB> point of iron to the initial stage of isothermal sintering at 1423K, transient alpha phase is maintained by preferential diffusion of phosphorous into iron. Since the diffusion rate of nickel in ferrite-alpha phase is higher than that in austenite-gamma phase at the same temperature, increased volume diffusion of nickel in the alpha phase promotes the sintering of the compacts.