The influence of ball milling conditions on the powder characteristics and sintering densification of MoCu alloy

Abstract

Mechanical alloying was utilized to produce Mo-30Cu(wt%) composite powder. The effects of milling conditions on the powder characteristics and sintering densification were investigated. The morphological evolution during the mechanical alloying process can be categorized into four stages: 1-individual Mo and Cu particles, 2-coexistence of Mo particles and blocky MoCu composite particles, 3-coarse irregular composite particles, and 4-refined near-spherical composite particles or lamellar MoCu composite particles, depending on whether process control agent (PCA) is added. The mechanical alloying degree of the MoCu composite powder was deepened gradually from stage 1 to 4, which is influenced by the ball milling parameters. As the milling speed and milling time increase, the lattice strain and the alloying degree of the MoCu composite powders increase while the grain size of molybdenum particles decreases, which is conducive to accelerating the sintering density. Among these ball milling parameters, an elevated milling speed notably accelerates the mechanical alloying process and the sintering density. Under the milling speed of 600 r/min, ball to powder ratio (BPR) of 10:1, and milling time of 4 h, the grain size, lattice strain, and average particle diameter of the composite powder were measured to be 48.4 nm, 0.247 %, and 21.04 μm, respectively, with the particle morphology being nearly spherical. The sintered density of the MoCu composite reached 98.1 %, larger than the other composites.