Microstructure and Mechanical Properties of Y2o3-Bearing Ti-48al-2cr-2nb Alloy Prepared by Selective Electron Beam Melting

A Ti-48Al-2Cr-2Nb alloy with uniformly dispersed nano-Y 2 O 3 addition was prepared by selective electron beam melting (SEBM). The effects of beam speed on the defects, microstructure and compressive properties were studied systematically. The Y 2 O 3 morphology gathered and exhibited a feathery structure when the beam speed was 1500mm/s due to the relatively low cooling rates. The Y 2 O 3 displayed an ellipsoidal structure, with a 90 nm size when the beam speed was 2100 and 2400 mm/s. Many nano twins were observed within the equiaxed γ grains due to the residual stress caused by quick cooling and different elasticity modulus between γ phase and Y 2 O 3 particles. The orientation relationship between nano-Y 2 O 3 and γ-TiAl matrices was determined by the selected area electron diffraction (SAED) and high-resolution transmission electron microscopy (HRTEM). The Y 2 O 3 -bearing TiAl alloys presented excellent compressive properties at room temperature, with the ultimate compressive strength reaching 3214 MPa, and the compressive strain was 38.05%. Finally, the strength mechanism of TiAl alloys with nano-Y 2 O 3 addition prepared by SEBM was discussed in detail