The last stage is a rapid softening course for all strain amplitude . further metallic phase shows : for all strain - controlled , the initial rapid cyclic hardening results from the strong interaction between precipitate strengthening phase and the dislocation ; as for strain amplitude lower than 0 . 95 % , the shearing of precipitate strengthening phase leads to the cyclic softening behavior 金相组织结构检查进一步表明，循环塑性应变作用将显著改变原始态合金中沉淀颗粒的几何形状、尺寸和分布状态，并由此改变位错与颗粒之间的交互作用行为，这一机制将对合金的循环硬化和软化起促进作用。
