Co含量及烧结温度对97W-Ni-Fe合金组织和性能的影响

The Effects of Co Content and Sintering Temperature on the Microstructure and Properties of 97W-Ni-Fe Alloy

钨基高比重合金因具有高密度、高强度、良好的塑性与韧性、优异的耐腐蚀性等综合性能,被广泛应用于航空航天、兵器、机械等各领域。本研究采用金属粉末注射成形技术制备97W-Ni-Fe合金,研究了不同Co含量和烧结温度对97W-Ni-Fe合金微观组织、密度、抗拉强度、延伸率和硬度的影响。结果表明,添加适量Co能够改善97W-Ni-Fe合金中钨颗粒与粘结相的润湿性,起到活化烧结的作用,降低烧结温度,提高合金相对密度;Co对合金的相组成影响不大,添加Co和未添加Co的两种合金相组成基本一致,均由W相和(Fe,Ni,Co)固溶体组成,没有金属间化合物出现。当Co含量为0.2%(质量分数)时,在氢气气氛下,烧结温度为1495℃、保温1 h,制备的97W-Ni-Fe合金具有最优异的性能,其相对密度为99.1%、抗拉强度为938 MPa、延伸率为11.3%和洛氏硬度为29.5。

Tungsten heavy alloys characterized by their high density,high strength,excellent plasticity and toughness,and superior corrosion resistance,are extensively utilized in aerospace,armament,and machinery industries.For its traditional moulding+machining manufacturing cost is expensive,this paper adopts employed metal powder injection molding technology to fabricate the 97W-Ni-Fe alloy and investigated the effects of varying Co contents and sintering temperatures on the microstructure,density,tensile strength,elongation,and hardness of the 97W-Ni-Fe alloy.The results show that the addition of appropriate amount of Co can improve the wettability of tungsten particles and the binder phase in the 97W-Ni-Fe alloy,activate the sintering,reduce the sintering temperature,and improve the relative density;Co exerts a minimal influence on the phase composition of the alloy;the phase compositions of the alloys with and without Co addition are essentially identical,both consisting of the W phase and a(Fe,Ni,Co)solid solution,with no intermetallic compounds observed.When the Co content is 0.2%(by mass fraction)and the alloy is sintered under hydrogen atmosphere by holding at 1495℃for 1 h,the alloy has the most excellent properties,with the densities,tensile strengths,elongations,and hardnesses of 99.1%,938 MPa,11.3%,and 29.5 HRC,respectively.This is due to the fact that the sintering is complete,the porosity is low,and sufficient liquid bonding phase is produced,which is uniformly distributed between the tungsten grains,making the tungsten grains bond more firmly,and the coordinated deformation ability of the tungsten grains is enhanced under tensile stress.