Modeling of grain boundary structures and properties in intermetallic compounds
Modeling of grain boundary structures and properties in intermetallic compounds
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DOI：
10.1016/0956-716x(91)90393-f
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发表时间：
1991-06
期刊：
影响因子：
--
通讯作者：
V. Vítek;S. P. Chen
中科院分区：
文献类型：
--
作者：
V. Vítek;S. P. Chen
This paper reports that one of the main reasons for studies of grain boundaries in metallic materials is the intergranular brittleness. This has been a long standing problem in structural steels and other disordered alloys and it is now well established that this phenomenon is associated with segregation of certain embrittling elements to grain boundaries. Thus in pure metals and in disordered alloys grain boundaries are not intrinsically susceptible to brittle fracture. On the other hand, intermetallic compounds often fracture in an intergranular manner even when there is no appreciable segregation of impurities to the grain boundaries. The most prominent example is Ni{sub 3}Al, which crystallizes in the face-centered-cubic based L1{sub 2} structure. This material is fully ductile in the single crystal form although exhibiting an anomalous temperature dependence of the yield stress, but brittle in the polycrystalline form. The intergranular fracture occurs in this material without any appreciable segregation of impurities to the grain boundaries and, therefore, the grain boundary brittleness appears to be an intrinsic property of this compound. However, a number of ordered alloys with the same crystal structure, for example Cu{sub 3}Au, are ductile as polycrystals. Hence, the first outstanding question is what is the physical reason for the intrinsic brittleness of grain boundaries in the materials like Ni{sub 3}Al.
