Grain Boundary Character Distributions of Zr and Ti GrainRefined Through Equal Channel Angular Pressing

초록

Commercially pure Zr and Ti were grain-refined through equal channel angularpressing (ECAP). With variation of the die design and the processing parameters such as the temperature and subsequent annealing, varieties of microstructures reulted in. Up to a strain of 1.8 was obtained by using a 90/20 die, which resulted in a grain refinement to about 200 nm with repeated ECA-pressing. The two metals showed a considerable differences in the initial texture. However, ECA-pressing converted the texture into a basically same preferred orientation, a strong (0001) texture inclined to the specimen axis. The grain boundary character distribution of both metals was such that the high angle boundaries was slightly higher than that in a random microstructure. Both the texture and the misorientation distribution of the severely deformed Zr and Ti persisted during the subsequent exposure to an elevated temperature.