Composition and Microstructure Analysis of Ti-24Al-17Nb-0.5Mo Alloy after YAG Laser Surface Remelting Treatment

摘要

Surface modification of Ti-24Al-17Nb-0.5Mo (at.%) with a substrate microstructure of (α_2+β+O) was conducted by using a YAG laser surface remelting technique. Microstructural observations showed that the melt zone consisted of distinct layers each of which was characterized in turn by featureless, columnar and equiaxed substructures, with characteristic sizes of the columnar and equiaxed regions ranging from 400 to 750 nm. XRD patterns showed that the melt zone consists of single B2 phase. Elemental segregation among different layers in the melt zone was detected by electronic probe microanalysis. Dimensions of the melt zone and the temperature field were theoretically analyzed and simulated with a three-dimensional heat transfer model. The numerical results were in good agreement with the experimental data.