Investigation On Microstructure And Properties Of W-Cr/Cu Composites

W-Cr/Cu composites were prepared by infiltration method. Based on analyzing sintering and infiltration processes, the effect of infiltration temperature on microstructure and properties of the material was studied when the ratio of W-Cr, the porosity of green compact and the sintering process of W-Cr skeleton were fixed. The differences of microstructure and properties of the composites with different composition were investigated by same sintering and infiltration processes. The composites were prepared in H2, N2, Ar and vacuum conditions respectively. The effects of sintering atmosphere on microstructure and properties were studied. The results showed:1. Cr particles were enclosed by Cr-W solid solution alloy after Cr powder and W powder were sintered if the grain size of Cr powder is larger than W powder. Around Cr particles more Cr-W solute was formed with prolonging sintering time. During infiltration process, Cr was dissolved and moved into the pores in W skeleton by Cu liquids and made W skeleton become W-Cr skeleton.2. With the increase of infiltration temperature, most even all Cr particles in the skeleton were dissolved gradually by Cu liquids, and Cu replacedtheir original places in the end. For the composites with high Cr content, the change of microstructure led to increase of hardness and decrease of electrical conductivity apparently. It is reverse for the composites having low Cr content.3. Hardness of the composites decreased and electrical conductivity increased with decrease of Cr content while infiltration temperature is same. Hardness increased and electrical conductivity decreased after adding Fe to the composites.4. The microstructure and properties varied with sintering atmosphere. Cr particles were replaced partially in H2 and N2 atmosphere while Cr particles were replaced entirely in Ar atmosphere and in vacuum condition. The composites had high electrical conductivity and low hardness in Ar atmosphere and in vacuum conditions. However, in N2 condition hardness was high but electrical conductivity was low because Cr was nitridized. In H2 condition the composites have good comprehensive properties.