Study of microstructure evolution and strengthening mechanisms in Mox(Nb3TaTi3Zr)100−x high-entropy alloys

A new series of high-entropy alloys denoted as Mox(Nb3TaTi3Zr)100−x, has been designed for aero-engine applications. The study focused on investigating the microstructural evolution and strengthening mechanisms of the alloys in response to varying Mo content. Results indicate that the alloys primarily display a BCC crystal structure. Notably, an FCC phase precipitates in the alloy when the Mo content reaches 30%. Furthermore, as the Mo content increases, the strength of the alloys significantly increases while their plasticity diminishes. The room-temperature yield strength of the alloys shows a substantial increase from 729 MPa (x = 0) to 1202 MPa (x = 25), while the yield strength at 1200 °C rises from 62 MPa (x = 0) to 498 MPa (x = 30). Concurrently, the microhardness of the alloys also increases from 247 HV (x = 0) to 471 HV (x = 30). The observed strengthening mechanisms include solid solution strengthening, fine grain strengthening, and precipitated phase strengthening.