晶界特征分布对哈氏合金力学性能的影响

采用扫描电镜、背散射电子衍射、透射电镜等手段对Hastelloy X(HX)合金的晶界特征分布、拉伸断口形貌及位错分布等进行研究。结果表明,HX合金室温拉伸断口由局部裂纹、微孔和大量的韧窝构成,微孔的形成与材料内部第二相颗粒分布有关。组织为晶内共格孪晶型的材料开裂是裂纹源扩展引起的,而组织为非共格孪晶型的样品是微孔聚集导致的开裂。分析表明,不同晶界特征分布的样品室温力学性能的差异,主要是晶粒尺寸和一次碳化物分布作用的结果。

Effect of grain boundary character distribution on mechanical properties of Hastelloy alloy

Effect of grain boundary character distribution (GBCD) on mechanical properties of the Hastelloy X (HX) alloy was investigated. Scanning electron microscopy (SEM), electron backscattered diffraction (EBSD) and transmission electron microscope (TEM) were employed to examine the GBCD, fracture morphology and dislocation distributes. The results show that the tensile fracture at room temperature is composed of local cracks, dimples, and voids related to second phase precipitates. The cracking of the material with intragranular coherent twin structure is caused by the propagation of crack source, while that with incoherent twins is induced by microvoid coalescence. It indicates that the difference of mechanical properties at room temperature of the specimen with different grain boundary character distributions is mainly due to the effect of grain size and primary carbide distribution.