Effect of Y Addition on Microstructure and Mechanical Properties of Ti-6Al-4V-2Cr-1.5Mo Alloy

The microstructures and mechanical properties of Ti-6Al-4V-2Cr-1.5 Mo-xY (x =0.1, 0.5, 1.0, 1.5, mass fraction) alloys are analyzed by means of OM, SEM, XRD, and TEM. It is found out that the microstructures of Ti-6Al-4V-2Cr-1.5 Mo-xY alloys are refined obviously after adding the rare earth Y element, that the Y₂O₃ phases formed are dispersed in the matrix, and that the mechanical properties of the alloy increase first and then decrease with the increase of the content of rare earth Y. The strength, hardness, elongation and properties of the alloy are the best when the addition of Y element is 0.5%. The mismatch between Y₂O₃ and the matrix α-Ti of the annealed Ti-6Al-4V-2Cr-1.5 Mo-0.5 Y is 0.141 3, which belongs to semi-coherent interface.