Metal injection molding of nanostructured W-Cu composite powder

TLDR: In this paper, a debinding cycle was identified which resulted in a high surface quality of the bionic parts, shape retention, and complete removal of binder, and an intermediate isostatic repressing step increased bionic density but did not contribute significantly to densification during sintering.

Abstract: Nanostructured W-Cu composite powder was fabricated by mechanical alloying. Compacts were then prepared from the powder in the as-milled conditions, and after a thermal reduction treatment, by metal injection molding using a multicomponent wax/polyethylene/stearic acid binder system. A debinding cycle was identified which resulted in a high surface quality of the bionic parts, shape retention, and complete removal of the binder. An intermediate isostatic repressing step increased the bionic density but did not contribute significantly to densification during sintering. Densities >96% of theorical were achieved in the injection molded compacts for both powder conditions via liquid phase sintering, notwithstanding the low brown density after debinding. This high sinterability is attributed to grain growth of the W and a double rearrangement process in the powder due to its intrinsic nanostructural characteristics.