Hard alloy iron boride-based powder - produced by atomising melt contg. boron, silicon, iron and boride-forming metals

摘要

Hard alloy powder comprises (by wt.) 3-20% B; 3% Al; 0,3-5% Si; 2.5% O; =1 of 5-35% Cr, 1-35% Mo, 0.5-30% W and 15% each of Ti, V, Nb, Ta, Hf, Zr, Co and Ni; balance (=10%) Fe. Powder is produced by (a) melting a mixt. of the above compsn. in an atmos. contg. 30 vol.% O2; (b) discharging a stream of the molten alloy in an inert gas atmos., and (c) impinging water or inert gas under pressure against the stream at an angle of 10-20 degrees wrt. the longitudinal axis of the stream to atomise the alloy. Powder can be (a) sintered with binder metal powder to produce a material which can replace high speed steels and cemented carbides for tools, dies, punches and heat resistant articles; (b) laminated or sprayed onto metal substrates to produce composites; or (c) mixed with metals or self-fluxing alloys followed by melting the matrix melt and segregating the hard alloy powder to produce dispersed composite materials. The Cr, Mo, W, Ti, V, Nb, Hf, Ta, Zr, Co and Ni partly replace the Fe in the Fe boride product. Cr boride improves the corrosion and oxidn. resistance, hardness and toughness (even at high temps.) of the sintered prod.