Fe－29wt％Ni合金超细微粒中的马氏体转变

MARTENSITIC TRANSFORMATION IN Fe-29WT% NiALLOY 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．每个微粒是一单晶体（ｂｃｃ或ｆｃｃ）．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．对奥氏体稳定化和马氏体及奥氏体的产生机制，进行了初步的讨论．

The ultrafine particle samples of Fe--29 wt$Ni alloy with differentaverage diameters(12 to 100urn) are prepared by the evaporation eondensationmethod in the atmosphere of N..They are a mixture of martensitio a'(bcc) and theaustenite y(fce).Each individual partiele is a single crystal (boo or fad). Thevolume fraction of martensite inoreaees evidently with the decrease of the averagediameter. During heating, as the average diameter deoreaees, the tempemture (Aaand Af) for a'--y reverie martensitic transformation comes down, and the range(AerAf) of the transformation temperature becomes narrower. However, duringcooling (up to 77K), we have not found the martensitic transformation. Thestabilization of the austering and the growth mechanism of the martensite andanstenite are preliminarily discussed in this Paper too.