Study on Microstructure Evolution and Microhardness of Ti₂AlNb-Based Alloy in Gradient Extrusion Process AITranslate

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Chinese Library Classification Number:TG379[金属学及工艺—金属压力加工]

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The effects of gradient extrusion on evolution of the grain orientation,grain size,and grain boundary orientation difference and mechanical properties of Ti₂AlNb-based alloy were studied by EBSD combined with microhardness test.The results show that preferred orientation<101>in the microstructure of Ti₂AlNb-based alloy gradually disappears after the gradient extrusion deformation,the grain size is gradiently distributed,and the structure of fine grains on the surface and coarse grains in the core is formed.The average grain size in the edge region decreases from the initial 20.64μm to 3.92μm,and the average grain size in the core region decreases to 11.24μm after gradient extrusion from two forming units.At the same time,the length of high-angle grain boundary in the edge region gradually increases from the initial 11166.5μm to 34905.8μm.The microhardness of the deformed sample shows an increasing gradient distribution from the core to the edge,and the average microhardness values of the first gradient and the second gradient increase by 9.9%and 11.5%respectively,compared with the initial sample.It provides theoretical support for the study of the large plastic deformation process of high temperature titanium alloy.