Grain and Grain Boundary Microstructures in Molybdenum Polycrystals Recrystallized from Single Crystals with Different Orientations

摘要

The morphology of grain and grain boundary (GB) microstructures was investigated to understand the development of microstructural heterogeneity in molybdenum polycrystals recrystallized from compressively deformed single crystal with different orientations of <001>, <110>, <111> and <112>. The orientation imaging microscopy was applied for quantitative analyses of various components of microstructures. The recrystallized microstructure consisted of randomly oriented grains and grain clusters with a similar surface orientation. In a grain orientation cluster, the frequency of low angle GBs was very high, and it depends on the surface orientation of the cluster. The lower surface free energy of grain orientation cluster results in the higher frequency of low angle GBs. There exist two specific orientation relationships between neighboring grain clusters such as {110}/{ 111} and {001}/{113}. The local GB character distribution (GBCD) in the clusters, particularly, the frequency of low angle GBs decreases with increasing grain size in each specimen and it also depends on the initial orientation of specimen and the type of grain cluster. On the other hand, the local GBCD of the region consisting of randomly oriented grains only depends on the grain size ; the frequencies of low angle and CSL GBs decrease with increasing grain size.