Dislocation-grain boundary interactions in martensitic steel observed through in situ nanoindentation in a transmission electron microscope
Dislocation-grain boundary interactions in martensitic steel observed through in situ nanoindentation in a transmission electron microscope
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DOI：
10.1557/jmr.2004.0474
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发表时间：
2004-12-01
影响因子：
2.7
通讯作者：
Morris, JW
中科院分区：
文献类型：
--
作者：
Ohmura, T;Minor, AM;Morris, JW
利用透射电子显微镜（TEM）原位纳米压痕研究了Fe-0.4 wt% C回火马氏体钢中位错-界面相互作用。在位错马氏体结构中成像了两种类型的边界：低角度（可能）板条边界和相干的高角度（可能）块边界。在低角度晶界的情况下，由压头引起的位错堆积在晶界上。随着压头的进一步深入，似乎达到了一个临界应力，并且在晶界的远端突然向邻近的晶粒发射高密度的位错。在高角度晶界的情况下，由压痕产生的许多位错被简单地吸收到晶界中，没有堆积或应变传递的迹象。这一惊人的观察结果是根据块体边界的结晶学来解释的。
Dislocation-interface interactions in Fe-0.4 wt% C tempered martensitic steel were studied through in situ nanoindentation in a transmission electron microscope (TEM). Two types of boundaries were imaged in the dislocated martensitic structure: a low-angle (probable) lath boundary and a coherent, high-angle (probable) block boundary. In the case of a low-angle grain boundary, the dislocations induced by the indenter piled up against the boundary. As the indenter penetrated further, a critical stress appeared to have been reached, and a high density of dislocations was suddenly emitted on the far side of the grain boundary into the adjacent grain. In the case of the high-angle grain boundary, the numerous dislocations that were produced by the indentation were simply absorbed into the boundary, with no indication of pileup or the transmission of strain. This surprising observation is interpreted on the basis of the crystallography of the block boundary.