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通过多轴锻造的方法实现了Fe-32%Ni合金奥氏体晶粒超细化,并进行深冷处理使之发生马氏体相变。采用透射电镜(TEM)观察了超细晶粒Fe-32%Ni合金奥氏体相变后马氏体的微观结构。结果表明,超细晶粒奥氏体相变后的马氏体片变得不再完整,部分马氏体片边缘变得弯曲,部分马氏体发生了中脊断裂现象;观察马氏体片的亚结构表明,有些马氏体片的亚结构是孪晶与高密度位错共存,有些马氏体片的亚结构转变为高密度位错。分析认为强变形马氏体特殊亚结构的生成是由于奥氏体组织细化大大提高了母相强度,加大了相变切变阻力和强变形奥氏体母相中大量位错的引入破坏了母相晶格原子排列的空间规律性等原因造成的。
The austenite grain size of Fe-32% Ni alloy was achieved by multi-axial forging method, and the martensite transformation took place by cryogenic treatment. The microstructure of austenite martensite after ultrafine grained Fe-32% Ni alloy was observed by transmission electron microscopy (TEM). The results show that the ultra-fine grain austenite martensite sheet becomes no longer complete, some of the martensite sheet edge becomes curved, some of the martensite occurred ridge rupture phenomenon; observed martensite sheet The sub-structures show that some of the martensite sheets have twin structures with high-density dislocations and sub-structures of some martensite sheets transformed into high-density dislocations. It is considered that the formation of the special sub-structure of strongly deformed martensite is due to the austenite refinement which greatly increases the strength of the matrix and increases the phase-change shear resistance and the introduction of a large number of dislocations in the strongly deformed austenite matrix The mother of lattice atoms arranged in the spatial regularity and other reasons.