Effects of Ti, Zr, and Hf on the phase stability of Mo_ss + Mo3Si + Mo5SiB2 alloys at 1600 °C

Understanding the stability of the three-phase Mo_ss + Mo3Si + Mo5SiB2 region is important for alloy design of Mo–Si–B-based refractory metal intermetallic composites. In this work, thermodynamic modeling is coupled with guided experiments to study phase stability in this three-phase region of the Mo–Si–B–X (X = Ti, Zr, Hf) system. Both the calculated and experimental results show that additions of Zr and Hf limit significantly the stability of the three-phase region because of the formation of the ternary phases MoSiZr and MoSiHf, while Ti addition leads to a much larger region of stability for the three-phase equilibrium.