研究了Cu-Zn-Al合金分别经水淬、分级淬火和淬火加时效处理后,马氏体的有序化程度及其和形状记忆效应(SME)之间的关系.有序化程度用一些特定马氏体线对的面间距差值△d来表征,线对指数应满足下式:(h_1~2-h_2~2)/3=(k_2~2-k_1~2)/n(对9R马氏体n=1,对18R马氏体N=4).分级淬火得到M18R马氏体,其△d值随分级等温时间而增大,与形状恢复能力η的提高一致.水淬得到M9R马氏体,刚淬火状态有相当大的△d和良好的SME,但室温停留使△d和η均下降,TEM点阵条纹象证实这是淬火过饱和空位在(001)_M基面聚集、降低有序程度的结果.淬火后高温时效(180℃)或过高的分级温度都会使△d和η下降,这与α相析出以及可能发生的溶质原子偏聚有关,都会降低有序程度.
The correlation between the shape memory effect (SME) and theordering degree of martensite formed during various heat treatment processes, e. g.ice water quenching, step-quenching and quenching plus aging, has been studied ina Cu-Zn-Al alloy. The ordering degree of martensite is characterized by the spacingdifference, Δd, of some pairs of diffracting planes, the indices of which satisfy theequation (h_1~2-h_2~2)/3=(k_2~2-k_1~2)/n. It is shown that the SME depends on Δd monoto-nically. The ordering extent of the DO_3 parent phase and of the martensite in turnincreases with the holding duration in the course of step-quenching, which may bethe main factor for enhancing the shape recovery rate η. The stabilization of themartensite may be associated with the clustering of vacancies which results in thelowering of the ordering degree. The decrease of the SME upon aging at highertemperature or holding at step-quenching temperature for longer time is due to theaccumulation of solute atoms and the precipitation of α-phase, which lowers theordering extent.
参考文献
| [1] | |
| [2] | |
| [3] | |
| [4] | |
| [5] |
- 下载量()
- 访问量()
- 您的评分：
-
10%
-
20%
-
30%
-
40%
-
50%