金属退火硬化现象及机理的研究进展

通常金属进行退火时都会发生软化现象,而对于一些特殊的金属或者合金,将出现退火硬化的反常现象。对纯金属、铜合金、镍钨合金、锌铝合金和铝合金等体系中退火硬化现象及机理进行了总结与分析。铝钪、铝镱和铝锆系合金中存在铸态直接退火硬化现象,而其它合金体系需要进行冷变形才会出现退火硬化现象。退火硬化的机理主要包括:晶界溶质偏析、晶界弛豫、第二相颗粒的晶界钉扎、位错源限制硬化、溶质偏析对孪晶边界迁移或位错滑动的钉扎效应、退火孪晶、第二相纳米粒子强化等。

Research progress on hardening effect and mechanism during annealing of metals

Softening of metals could be achieved during annealing, generally. However, for several specific metals or alloys, the abnormal phenomenon of annealing hardening occurred. The phenomenon and mechanism of hardening effect during annealing in pure metal, Cu alloy, Ni-W alloy, Zn-Al alloy and Al alloy were summarized. It was noted that the annealing hardening could be detected for the as-cast Al-Sc, Al-Yt and Al-Zr alloys, while cold deformation was necessary for the other types of alloys to obtain the annealing hardening. The mechanisms of annealing hardening were summarized as follows, including solute segregation on grain boundary, grain boundary relaxation, grain boundary nailing of the second phase particles, dislocation source-limited hardening, pinning effect of segregated solute atoms on twin boundary migration or dislocation sliding, annealing twins and strengthening of the second phase nanoparticles, etc.