Effect of Cr addition on microstructures andnanohardness of rapidly solidified Ti-48Al alloy

摘要

In this present work, the microstructure and nanohardness of rapidly solidified Ti-48 at-%Al alloy with various Cr additions were experimentally investigated using the single roller melt spinning technique. Ti-48Al alloy with various Cr additions were prepared by arc melting for comparison. In the arc melted alloy, the volume fraction of the interdendritic y phase decreases, and the lamellar structure and the B2 phase increase with the increase in Cr addition. After rapid solidification, the Ti-48Al alloy consists of the y phase and α_2 the phase, with the y phase as the matrix. The α_2 phase exists as particles or in lamellar structure, which embed in the matrix. With 2 at-%Cr addition, the alloy ribbons mainly consist of equiaxial α_2 grains and small particles of the B2 phase, with few lamellar structures occasionally found at the triple grain boundary. Increasing Cr content to 4 at-%, the grain size of the B2 phase increases, and lamellar structures disappear. The change in nanohardness was discussed based on the microstructural observations. It shows a certain increase in the nanohardness as Cr content increases to 4 at-%. This can be attributed to the changes in the microstructures.