Microstructure and high-temperature deformation performance of liquid-dispersed evaporated Nano-ZrTiO4 doping molybdenum alloy

Abstract

To enhance the low-temperature plasticity and high-temperature strength of molybdenum alloys, we introduce a method of uniformly dispersing nano-ZrTiO4 particles within and between molybdenum grains. This approach effectively eliminates the formation of hard agglomerations between particles and leads to a further refinement of molybdenum grains. The research employs molecular level solid-liquid doping and subsequent liquid dispersion evaporation techniques to successfully synthesize Mo-ZrTiO4 nano-composite powder following H2 reduction. Subsequently, a novel fine-grained Mo-ZrTiO4 alloy sintered billet is successfully fabricated through cold isostatic pressing and high-temperature sintering. To assess the efficacy of the process, three sets of comparative experiments are designed, each employing different methods. The comparative studies have revealed compelling advantages of the liquid dispersed evaporated fine-grained samples of Mo-ZrTiO4. The key advantages identified are as follows:the samples demonstrate a refined grain size, ranging from 2 μm to 4 μm. Within the samples, the nano ZrTiO4 particles have an average size of approximately 200 nm. The density and Vickers hardness of the samples is measured at 10.21 g/cm3 and 268.5 ± 17HV0.2, respectively. The samples exhibit impressive toughness even at room temperature, notably, the high-temperature compressive strength of these samples surpasses that of the deformed samples reported in previous literature concerning this system. The mechanism of liquid dispersion evaporation method in grain nucleation, growth, and powder drying, reduction, and sintering processes was systematically elaborated. Simultaneously, a detailed analysis was conducted on two high-temperature strengthening mechanisms that impact the mechanical properties. The results indicate that this excellent performance can be attributed to the synergistic effect of both fine grain strengthening and uniform dispersion strengthening of second-phase nanoparticles.