Fe－29wt％Ni合金超细微粒中马氏体转变热效应研究

A Study on the Thermal Effect of Martensitic Transformation in Fe-29wt%Ni Alloy Ultrafine Particles

在Ｎ＿２气氛中，用蒸发冷凝法，制备了不同平均粒径（１２～１００ｎｍ）的Ｆｅ－２９ｗｔ％Ｎｉ合金超细微粒样品。它们是马氏体α＇（ｂｃｃ）和奥氏体γ（ｆｃｃ）的混合体。随样品的平均粒径减小，马氏体体积分数明显增加。在加热过程中，随平均粒径减小，α＇→γ逆马氏体转变温度（Ａ＿ｓ和Ａ＿ｆ）降低，转变温度范围（Ａ＿ｓ－Ａ＿ｆ）变窄。在冷却过程中（直到７７Ｋ），没有发现γ→α＇马氏体转变。对奥氏体稳定化的原因，进行了初步的讨论。

The ultrafine-particle samples of Fe-29wt%Ni alloy with different average particle sizes(12 to 100nm) are prepared by the evaporation-condensation method in N_2 atmosphere,They exhibita mixture of martensite a'(bcc) and austeniteγ(fcc)phases. The volume fraction of martensite increasesmarkedly with the decrease of the average particlesize,During heating,as the average particle sizedecreases,the temperature(A_s and A_f)for α'→γreverse martensitic transformation decreases,and therange(A_s-A_f )of reverse transformation temperaturebecomes narrower.During cooling(down to 77K),we have not observed γ→α'martensitictransformation. The stabilization of austenite ispreliminarily discussed in this paper.