Microstructure evolution and the mechanical properties of in-situ Ti2AlCw-NbC@TiBx/TiAlNb composite with high performance

This manuscript reports an innovative preparation method of TiAl matrix composites. The mixed AlNb powder and B4C powder were put into TiAlNb alloy melt after ball milling. With the help of the reaction in AlNb/B4C powders and the in-situ reaction of various elements in TiAlNb alloy melt, hybrid Ti2AlCw and NbC@TiBx core shell structure with high dispersion and good interface bonding were synthesized and introduced into TiAlNb alloy. The analysis shows that the NbC/TiBX of the core-shell structure was based on the in-situ reaction on the NbC substrate obtained in high-energy ball milling and was formed by the in situ reaction in the TiAlNb melt. The NbC@TiBx structure and the in-situ Ti2AlC whiskers both have excellent interfacial bonding with TiAl matrix. In this TiAlNb composite with dual-scale reinforcements, the combination of multiple strengthening/toughening mechanisms improves the mechanical properties of TiAlNb alloy matrix. The in-situ Ti2AlCw and NbC@TiBx hybrid reinforced TiAlNb composite was prepared successfully. Room compression tests show that the fracture stress and strain of the composite are increased from 1548 MPa, 20.6% to 2678 MPa, 29.1%. And the high temperature compression tests (at 1073 K) show that the fracture stress and strain of the alloy are increased from 641 MPa, 23.4% to 1012 MPa, 35.9%.