Cu-Zn-Al合金马氏体稳定化与母相有序态

STABILIZATION OF MARTENSITE AND PARENT PHASE ORDERING IN A Cu-Zn-Al ALLOY

采用X射线衍射和内耗测量研究了Cu-Zn-Al合金不同热处理条件对马氏体相变和母相有序态的影响。研究表明,“淬火-时效”试样从室温加热到320℃马氏体完全消失为止始终未发生逆相变。分级淬火短期等温试样出现B2?9R和DO_3?18R两种马氏体相变共存。随着等温时间的增长,B2?9R相变消失,与此同时DO_3?18R相变增强。然而,淬火后立即上淬到100—150℃等温的试样只出现B2?9R相变,即使等温时间增长也能继续保持。显然,从高温快冷不能抑制A2?B2有序,却可以抑制B2?DO_3有序。虽然分级和上淬处理时母相所处的湿度相同,但其有序态却各异,足够的空位浓度是发生B2?DO_3有序转变的必要条件。文中讨论了Cu-Zn-Al合金马氏体稳定化的可能机制。

The reverse transformation has never occurred in a quenched and aged specimen heating from room temperature to 320℃ at which the martensite disap- pears thoroughly. Both B2?9R and DO_3?18R coexist in step-quenched and short-time isothermally treated specimen. As prolonging the isothermally holding, the B2?9R disappears and DO_3?18R intensifies. B2?9R occurs only in specimen quenched and up-quenched immediately to 100--150℃. Rapid quenching from high temperature will depress the B2→DO_3 ordering but not the A2→B2 one. A more enough concen- tration of vacancy is a necessary condition of occurrence of B2→DO_3 ordering. The possible mechanism for stabilization of martensite in Cu-Zn-Al alloy was also discussed.