In-situ alloying modulation in additive manufacturing of titanium-tantalum alloy: From melt pool modelling to process development

In-situ alloying by additive manufacturing (AM) is a versatile and efficient approach for the rapid development of new materials. However, its successful implementation critically depends on achieving effective and homogeneous alloying during the process — an outcome that is highly sensitive to the process parameters and remains challenging to predict. In this study, a process map incorporating the degree of in-situ alloying was developed for laser powder bed fusion (LPBF) of a titanium-tantalum binary alloy with 30 wt% tantalum (Ti-30Ta) by correlating single-track melt pool characteristics with bulk sample properties through the integration of machine learning and analytical modelling. This approach coupled and quantified the relationship between the melt pool mode and mechanical properties, refining the process window for the Ti-30Ta alloy system. Under the defined process window, fabricated Ti-30Ta bulk samples exhibited optimised mechanical properties, with an ultimate tensile strength (UTS) of 745.8 MPa and an elongation of 16.9 %. Synchrotron X-ray diffraction analysis confirmed that the microstructure is predominantly composed of orthorhombic α″ phase. Furthermore, the samples demonstrated enhanced biocompatibility and a favorable balance between structural density and alloy homogeneity, underscoring their broad application potential. Beyond its direct implications for Ti-30Ta alloy, this study establishes a transferable framework for in-situ alloying process maps development across various alloy systems, paving the way for more advanced alloy development and manufacturing strategies in the field of in-situ alloying AM and beyond.