Microstructural Evolution Of Ta-W Alloy After Cold Rolling And Annealing

Metals with body center cubic(BCC)crystal structure are widely used in the industries.However,their deformation microstructure were investigated very rarely and their deformation and mechanism is still unclear.Besides the relavant studies mainly focusing on BCC steels,there is little research on refractory metals like Ta.In this paper,a Ta-W alloy was selected as the original material.Samples with different strains were prepared by cold rolling,and the deformed samples were annealed under vacuum to study the recrystallization behavior.The X-ray diffraction(XRD)test technique was used to analyze the textural evolution after cold rolling.Microstructural evolution after different strains and recrystallization behavior after annealing were analyzed by means of electron backscatter diffraction(EBSD).The following conclusions are drawn:1 The grain size of the original sample,with an average grain size of approximate 26 μm,spans from a few microns to more than a hundred microns,and a slight γ texture is found in the texture.With the increasing of deformation strains,the original γ texture gradually disappears.After 50% deformation,the α texture and γtexture start to form and their strength gradually increases.Finally,strong α texture andγ texture are found in the Ta-W alloy;2 After deformation grains,In the samples deformed to low strains,are segmented into several domains.large accumulative misorientation can be built in a short distance and some domains are found to rotate in different directions.With increasing deformation strain,shear bands and S-type bands are found.and the morphologies of the bands in grian interiors and near grain boundaries are quite different;3 A weak orientation depencance of the microstructure is found in the present results.Grains with a single deformation band have random orientations,while most grains with two deformation bands have α texture with the exception of a few γorientated grains;4 During annealing,texture in the Ta-W alloy gradually changes with time increasing but a more random texture eventually develops in the fully recrystallized samples.Recrystallizing grains have a growth advantage in the RD direction.But eventually,a fully recrystallized microstructure with equiaxed grain and nearly random orientation is found.The evolution of the misorientation distribution is consistent with the microstructural evolution.