Fluidity Improvement of Ti2AlNb-based Alloys with Enhanced TensileStrength and Oxidation Resistance through Composition Optimization

Author of the article:WU Yunjie1, ZHANG Pengfei1,2, SUN Feng3, ZHOU Yu3, YANG Haoxue1, WANG Jun1,3

Author's Workplace：1. State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi'an 710072, China; 2. AECCGuizhou Liyang Aero Engine Co., Ltd., Guiyang 550014, China; 3. Innovation Center NPU Chongqing, Chongqing 401135,China

Key Words：Ti2AlNb-based alloy; composition optimization; fluidity; solidification mechanism

Abstract：Phase diagram calculations combined with machine learning modelling were used to investigate how multiplealloying elements influence the castability and service performance of Ti2AlNb-based alloys. The thermophysical parametersassociated with melt fluidity were calculated via phase diagram software, and machine learning models were developed toassess the effects of alloying elements on the oxidation resistance and mechanical properties. On the basis of the integratedanalysis, alloy compositions that improve both castability and service performance were identified and further validatedthrough fluidity experiments, and the mechanisms underlying the increase in melt fluidity were also investigated. Theresults indicate that the stopping-flow behavior of Ti2AlNb-based alloy is typical of alloys exhibiting a wide solidificationtemperature range. The improved fluidity mainly results from a reduced solidification temperature, which increases meltsuperheating and promotes melt flow. In addition, microalloying elements serve as effective grain refiners, resulting insignificant reductions in the grain size. The refined grains suppress the development of an extensive dendritic networkduring solidification, thereby reducing the flow resistance in the semisolid region. Overall, the combined effects ofthermodynamic optimization and microalloying offer a viable strategy for enhancing the castability and service performanceof Ti2AlNb-based alloys