Effects of Cr and W on Microstructure and Mechanical Properties of TiAl-Nb Alloys

Ti-Al-Nb-xCr-yW-Si (x=1.5, 2.5, 3.5, y=0.5, 1.0, 2.0, at%)alloys were prepared by vacuum arc melting.The microstructure and compressive mechanical properties of alloys with the change of Cr and W contents were studied.The results show that the microstructure of as-cast alloys is mainly composed of lamellar structure (α₂+γ)and B2 phase.With the increase of Cr and W contents, B2 phase increases and lamellar structure decreases.When Cr and W increase to 3.5% and 2.0%, coarse feather like structure appears in alloys.β phase stability of Cr is stronger than that of W element.The peak stress of the alloy in compression decreases with the increase of Cr content, while the peak stress of alloy in compression increases with the increase of W content, and Ti-44Al-5Nb-2.5Cr-1.5W-0.5Si alloy shows the highest peak stress and ductility.