Microstructure evolution during austenite reversion in Fe-Ni martensitic alloys
Microstructure evolution during austenite reversion in Fe-Ni martensitic alloys
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DOI：
10.1016/j.actamat.2017.10.068
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发表时间：
2018-02
期刊：
影响因子：
9.4
通讯作者：
H. Shirazi;G. Miyamoto;S. H. Nedjad;Tadachika Chiba;M. N. Ahmadabadi;T. Furuhara
中科院分区：
文献类型：
--
作者：
H. Shirazi;G. Miyamoto;S. H. Nedjad;Tadachika Chiba;M. N. Ahmadabadi;T. Furuhara
研究了Fe-11、18和23ni（质量%）合金在连续加热和afc以上等温保温反转变过程中的组织变化。用共聚焦激光扫描显微镜（CLSM）原位观察和原位/非原位电子背散射衍射（EBSD）分析直接观察反转变。结果表明，随着Ni含量的增加，奥氏体还原的起始温度（As）逐渐降低，但高于0℃。Fe-23 Ni合金的反转变伴随着明显的表面起伏，表明该合金发生了马氏体反转变。EBSD测量结果表明，该合金中形成的反向奥氏体晶粒与先前的奥氏体晶粒具有几乎相同的晶体取向，这意味着由于奥氏体记忆效应，先前奥氏体晶粒的取向和边界被保留了下来。通过进一步保持在8℃以上，还原奥氏体进行自发再结晶。fe - 18ni合金在回火过程中也表现出类似的组织变化。在Fe-18和23ni合金的还原过程中，逆转奥氏体和初始马氏体之间存在近kurdjammov - sachs （K-S）取向关系。而当Ni含量降低到11%时，逆转奥氏体与初始马氏体之间没有特定的取向关系，表明逆转机制由马氏体转变为无分割扩散（块状）机制。
The change of microstructure during reverse transformation by continuous heating and isothermal holding above Aftemperature were studied in Fe-11, 18 and 23 Ni (mass %) alloys. In-situ observation by using confocal laser scanning microscopy (CLSM) and in-situ/ex-situ electron backscatter diffraction (EBSD) analysis were used for direct observation of reverse transformation. It was found that the start temperatures (As) for austenite reversion decrease with increasing of Ni content while they are higher than T0temperatures. Reverse transformation in the Fe-23 Ni alloy is accompanied with a sharp surface relief indicating that reverse transformation occurs martensitically in this alloy. EBSD measurements show that reversed austenite grains in this alloy are formed with nearly identical crystallographic orientations to the prior one, which means orientations and boundaries of prior austenite grains are preserved due to the austenite memory effect. By further holding above Aftemperature spontaneous recrystallization of reverted austenite proceeds. The Fe-18 Ni alloy also shows similar microstructure change during reversion. Near Kurdjamov-Sachs (K-S) orientation relationship is found between reversed austenite and initial martensite during reversion of the Fe-18 and 23 Ni alloys. However, when the Ni content is decreased to 11%, no specific orientation relationship is found between reversed austenite and initial martensite, indicating that the reversion mechanism is changed from martensitic to partitionless diffusional (massive) mechanism.