Preparation of W-Cu alloy with high density and ultrafine grains by mechanical alloying and high pressure sintering

Abstract

W-20 wt%Cu alloy, with a high sintering density of 99.2% theoretical density (%TD), ultrafine grain size of 500nm, and hardness of 310HV, was fabricated by mechanical alloying and high pressure sintering (HPS). The changes of morphology and structural evolution of W-Cu powders during mechanical alloying process were observed and studied, and the effects of temperature and pressure on the density of sintered compacts were studied. Results showed that nanostructured (NS) mechanical alloyed (MA) W-Cu powders were obtained after a 40h milling at a milling speed of 400rpm, and the W-Cu alloy had nanocrystalline structure and shape retention with nearly full densification when the HPS of NS MA W-Cu powders was carried out at 1050°C with a pressure of 40MPa. The densification behavior of NS MA W-Cu powders during HPS was also studied, including a nanosintering within the MA powders during heating and a global rearrangement and sintering when an external pressure was applied.