Effect of Restricted Multi-Directional Forging on the Microstructure and Properties of Ti2AlNb-Based Alloy
Ti2AlNb-based alloy was subjected to three passes of isothermally restricted multi-directional forging(R-MDF)in the B2+O phase region.The microstructure of the deformed alloy samples was ana-lyzed using metallographic microscope,X-ray diffractometer,scanning electron microscope,and transmis-sion electron microscope.Quantitative analysis of the total volume fraction of O phase,width and volume fraction of lamellar O phase,and size of equiaxed O phase in each pass of multi-directional forging was con-ducted using Image software,aiming to study the deformation behavior of O phase in different passes.Vickers hardness test was conducted on Ti2AlNb-based alloy samples in different passes to reveal the rela-tionship between microstructure and microhardness after multi-directional forging.The research results show that after deformation,coarse lamellar O phase fragments and refines into equiaxed O phase.After different passes of multi-directional forging,the size of equiaxed O phase initially increases from 0.57 μm in the first pass to 1.24 μm in the second pass and then gradually decreases,reaching an average size of ap-proximately 0.84 μm after the third pass.Compared with the initial sample,the microhardness of the sam-ples in each pass increases by approximately 15.4％,22.2％,and 14.8％,respectively.
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