A Comparative Study on Microstructure and Mechanical Properties of Ti‐43/46Al–5Nb–0.1B Alloys Modified by Mo. Issue 4 (12th December 2019) - Yang, Yong
Abstract : To improve mechanical properties of TiAl–Nb alloys and obtain effects of Al content on microstructure, Ti‐43/46Al–5Nb–0.1B– x Mo alloys are prepared. Phase constitution, macro‐/microstructure volution, and mechanical properties of them are investigated systematically and compared in detail. Results show that the lamellar colony size refines, B2 phase increases and Al‐segregation in interdendritic regions aggravates with the increase in Mo content. The increased B2 phase is attributed to the increased Mo segregated at the grain boundaries during β/α transformation, and the aggravated Al‐segregation is attributed to the increased Al rejected into the interdendritic areas during L/β solidification. Compressive results show that the strength and strain increase about 150 MPa and 6% when the Mo content increases to 0.8 at% for Ti‐43Al–5Nb–0.1B– x Mo alloys; they increase about 343 MPa and 4% when Mo content increases to 1.2 at% for Ti‐46Al–5Nb–0.1B– x Mo alloys. Both the strength and strain decrease when Mo content further increases. The grain refinement strengthening and solid solution strengthening caused by Mo are contributed to the improved strength and strain. However, excessive B2 phase and severe Al‐segregation deteriorate the mechanical properties of the alloys, which act as the cracking sources. Abstract : Herein, schematic diagram of the comparison of the microstructures and mechanical properties of Ti‐43/46Al–5Nb– x Mo alloys are shown. The microstructures refined and the B2 phase increased when Mo added. The Ti‐46Al–5Nb– x Mo alloys exhibit coarser microstructures, lower B2 phase, and higher fracture strain but lower compression strength than Ti‐43Al–5Nb– x Mo alloys when added the same Mo contents.