Microstructure and Mechanical Properties of TiAl Alloys with Gd Densified by Spark Plasma Sintering.

Dense Ti-48Al-2Cr-2Nb-xGd (x = 0, 0.15, 0.3 at. %) alloys with different compositions were prepared by spark plasma sintering (SPS). The phase composition and microstructure of sintered alloys were studied by x-ray diffraction analyzer (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). The mechanical properties were determined by room-temperature compression test. Results show that Gd₂O₃ and Al₃Gd are the gadolinium-rich precipitates formed at the boundary of the original powder particles after the addition of Gd. However, with the increase in Gd addition, the precipitates will gather and grow together, and the dispersed fine precipitates play the role of dispersion strengthening, while the large particles gathered together play the opposite role. The TiAl alloy added with 0.15%Gd has the best compressive properties, and the ultimate compressive strength and fracture strain are 2750 MPa and 43.59%, respectively, which are significantly better than the cast alloy and the alloy without Gd. [ABSTRACT FROM AUTHOR]