High-temperature Mechanical Properties and Dynamic Recrystallization Mechanism of in situ Silicide-reinforced MoNbTaTiVSi Refractory High-entropy Alloy Composite

The hypoeutectic composite material composed of BCC phase and in situ precipitated Ti5Si3 was prepared by adding Si into MoNbTaTiV high-entropy alloy. The obvious oriented in situ Ti5Si3 phase formed eutectic phase with BCC phase in the inter-dendritic area, which leads to excellent properties of the composite. The alloy exhibits ultra-high yield stress of 718 MPa at 1200 degrees C and obvious compression plasticity. After reaching the maximum strength, dynamic recovery (DRV) and dynamic recrystallization (DRX) caused soften phenomena. The DRX mechanism of the dual-phase eutectic structure is analyzed by electron backscatter diffraction. The DRX of the BCC phase conforms to the discontinuous DRX and continuous DRX mechanisms, while the Ti5Si3 phase has a geometric DRX mechanism in addition to the above two mechanisms. The high performance of this composite has enough potential high-temperature applications such as nuclear and aero engine.