Tailoring the Microstructure and Mechanical Properties of Ti1.5NbZrV0.4Mo0.6 High Entropy Alloy via C and Si Doping

In order to obtain high-strength lightweight refractory high entropy alloys, carbides and silicides are introduced to further improve the specific strength, and the individual effects of C element (Ti_1.5NbZrV_0.4Mo_0.6C_x, x = 0.1, 0.3, 0.5, 0.7, 0.9, molar ratios), and the synergistic effects of C and Si (Ti_1.5NbZrV_0.4Mo_0.6(SiC)_y, y = 0.5 and 1.0, molar ratios) on the microstructure and mechanical properties of Ti_1.5NbZrV_0.4Mo_0.6 alloy are systematically explored. The results show that the addition of C element promotes carbides, which improves yield strength of the alloys from 1304 to 1490 MPa at room temperature (RT) and from 586 to 823 MPa at 800 °C. The co-doping of C and Si generates a complex microstructure composed of body centered cubic phase, carbides, and silicides, which leads to the increase of yield strength from 1540 to 1933 MPa RT and from 591 to 797 MPa (800 °C). Furthermore, the specific yield strength increases from 224 to 297 MPa g⁻¹ cm³ RT and from 86 to 123 MPa g⁻¹ cm³ (800 °C). This study provides an important reference value for the doping of nonmetallic light elements into refractory high entropy alloys.