Effect of Ti Addition on the Microstructure and Mechanical Properties of L-PBF-Fabricated CoCrNi Medium-Entropy Alloys

Laser powder bed fusion (L-PBF) delivers significant advantages for manufacturing medium-/high-entropy alloys (MEAs/HEAs), owing to its near-net-shape manufacturing and the ability to fabricate complex geometries. In this paper, a series of (CoCrNi)100−xTix (x = 0, 1, 2, 4 wt.%) MEAs were successfully fabricated by L-PBF technology, and the effect of Ti addition on the microstructure and mechanical properties was systematically investigated. The results show that L-PBF CoCrNi-4wt.%Ti alloy processed with a laser power of 275 W and the scanning speed of 1000 mm/s delivered a high yield strength of 777.5 MPa and ultimate tensile strength of 1054.5 MPa, along with a ductility of 20.8%. Compared with the L-PBF CoCrNi alloy, the CoCrNi-4 wt.%Ti alloy shows an increase in yield strength from 684.8 to 777.5 MPa and in ultimate tensile strength from 961.1 to 1054.5 MPa, accompanied by a decrease in uniform elongation from 27.8% to 20.8% (a reduction of seven percentage points, approximately 25% relative). The present work offers a promising pathway to improve the performance of additively manufactured medium-entropy alloys.