Fabrication of WC-6Co-1.5Al Hardmetals by Electric Current Sintering

The fabrication of WC-6Co-1.5Al (wt%) hardmetals by electric current sintering from milled powders was studied.When the peak,base,repetition frequency and duty ratio of pulse electric current are prechoosed as 3 000 A,360 A,50 Hz and 50%,constant current,sintering pressure and total sintering time are prechoosed at 1 500 A,30 MPa and 6 min,the alloy has optimal properties by sintering of 1min pulse electrical current and subsequent 5 min constant electrical current.The density,hardness and transverse rupture strength of the as sintered alloy are 14.22 g/cm3,94 HRA and 1 660 MPa,respectively.The corresponding average WC grain size is about 500 nm.In the case of single constant current being supplied to sinter milled powders,the sintered density could be increased by intensifying the current,even being more than 14.22 g/cm3.However,too intensive constant current reduces the sintered density reversely.It is proved that the hardness and transverse rupture strength by single constant current sintering are lower than that by the sintering of 1min pulse- and 5min constant current.