Abstract
The purpose of this paper is to discuss the metallurgical characteristics of Fe-Cr and Fe-Cr-Ni a phase powders, containing 42.5%Cr and 44.5%Cr-17.5% Ni respectively, as raw materials for powder metallurgy. Alloying phenomena of the a phase powder were observed in the process of formation of Fe-25%Cr-28%Ni austenitic alloy by means of saturation magnetization, X ray diffraction method, and optical microscopy.
The results are summarized as follows:
(1) Fe-Cr a phase powders were transformed into a phase within about 5 minutes at 1000°C, and these powders behaved as Fe-Cr a phase alloy powders above 1000°C.
(2) Fe-Cr-Ni p phase powders were decomposed into y phase in which small particles of the a phase were dispersed.
During heating over 1000°C, these a phase particles grew into larger particles and then dissolved into the γ phase.
(3) Cr had been diffused from the a phase into matrix powder before it was transformed into the a or (a+γ) phase.
(4) Larger shrinkage was obtained when the compact contained Fe-Cr a phase powders than those of Fe-Cr-Ni.
