Phase, microstructure, and properties of fine-grained Mo-W-Cu alloys prepared by mechanical alloying and large electric current sintering

Abstract

BackgroundThe novel Mo-W-Cu alloy exhibits relatively low density and good high-temperature resistance. However, due to the poor sintering ability of the mixed powders, enhancing the densification and properties of the alloys remains a challenge. MethodsWe prepared fine-grained Mo-W-Cu alloys by a combination of mechanical alloying (MA) and large electric current sintering (LCS) at relatively low temperatures and short durations and then conducted a comprehensive systematic inquiry into the densification behavior, phase, microstructure, and properties of the resulting alloys. Significant findingsIt was revealed that the MA process did not affect the phase-type of the alloy but significantly altered its densification, microstructure, and properties. In addition to the pre-existing Mo, W, and Cu phases, XRD and TEM results unveiled three new phases formed in the alloys, namely Cu0.4W0.6 intermetallic compound, Mo-W solid solution, and Mo-Cu solid solution, none of which are present in an equilibrium state. The MA process is pivotal in refining powder particles, fostering elemental homogeneity, thereby enhancing the densification of Mo-W-Cu alloys. In comparison, the microstructure of the Mo-W-Cu alloys prepared with the MA process becomes denser and more homogeneous, accompanied by a marked improvement in both densification and properties. Notably, Mo-W-Cu alloys prepared with a ball milling time of 40 h exhibit optimal properties, achieving an approximate relative density of 98 %.