Fabricating TiAl alloys with various compositions by twin-wire arc AM.

TiAl alloys with different Al atomic compositions, i.e. Ti45Al, Ti48Al, and Ti51Al, were produced via double-wire arc-based additive manufacturing by altering the aluminum wire feed rate. The microstructure and mechanical performance of deposited parts were researched. By changing the aluminum composition from 45 at% to 51 at%, the microstructure in the uniform area transforms from equiaxed α₂/γ lamellar and near-lamellar colonies to dual-phase structures and near-lamellar colonies, the volume fraction of α₂ phase decreases from 46.5% to 12.4%, and the total microhardness decreases from 411 to 356 HV. As the aluminum composition increases, the compressive strength presents an increasing trend first and then a decreasing trend, and the compressive ratio presents an increasing trend. The maximum compressive strength and compressive ratio in the vertical and horizontal orientations are 1822.5 MPa, 1732.5 MPa, 19.9%, and 20.2%, respectively. [ABSTRACT FROM AUTHOR]