Grain Refinement and Grain Boundary Character Distribution of Commercially Pure Molybdeum Produced by Equal Channel Angular Pressing(ECAP).

초록

Commercially pure Mo was grain-refined by ECAP at 500°C. A total of 8 passes of ECAP was conducted and the resulting microstructure and texture were studied. In the as-deformed state, the development of the microstructure and texture was influenced by the strain paths during repetitive ECAP. With four passes of ECAP, lamellar grains of 300 nm in thickness and equiaxed grains of 500 nm were obtained via route A and C, respectively. The grain refinement achieved by the ECAP was attributed to the evolution of low angle boundaries into high angle boundaries with increase in the number of pressing. Like other bcc metals, a strong fiber texture consisting of <111>θ and {110}θ components was generated in Mo by ECAP. The characteristics of the texture strongly implied that the {110}<111> slip systems were in operation, which is thought to be the main mode of deformation during the severe plastic deformation