Evaluating compressive property and hot deformation behavior of molybdenum alloy reinforced by nanoscale zirconia particles

Abstract

The paper deals with the fabrication of molybdenum alloy bars with different ZrO2 content via a series of processes, involving hydrothermal synthesis, co-precipitation, co-decomposition, powder metallurgy and rotary swaging. The compressive properties of molybdenum alloy bars were tested at various temperatures from room temperature to 1400 °C, and hot deformation behavior at different temperatures and strain rates was studied. The results show that ZrO2 particles with the size of tens of nanometers are evenly dispersed in Mo matrix, and ZrO2(110) and Mo(110) have a non-coherent interface due to a larger lattice misfit 13.57%. ZrO2 particles could significantly reduce grain size of molybdenum alloy and improve its compressive properties. When the volume content of zirconia increases from 0% to 2.0%, the grain size of molybdenum alloys annealed at 1200 ℃ decreases sharply from 55.9 µm to 3.5 µm. The compressive yield strength (CYS) of Mo-2.0 vol%ZrO2 annealed at 1200 °C is 674 MPa at room temperature, which is 65.6% higher than that of pure Mo. The high temperature CYS of Mo-2.0 vol% ZrO2 at 1400 °C is 176 MPa, increasing 49.6% higher than that of pure Mo. Compared with the previous works, the peak flow stress of the new Mo-2.0 vol%ZrO2 has been significantly improved. Adding of 2.0 vol%ZrO2 increases the initial temperature of dynamic recrystallization to 1200 °C, and effectively prevents the grain growth of dynamic recrystallization even at the increased deformation temperature of 1400 °C.