Effects of Co and Co + Mo additions on tensile properties of tungsten heavy alloys: first-principles study and experimental investigations

The present work illustrates the deformation behaviour of tungsten heavy alloys (WHAs) using first-principles calculation under tensile stress of three virtual alloy systems comprising the matrix phase and a W-grain along with two fcc–bcc interfaces. The energy values of the alloy systems decrease with the additions of Co and Co + Mo in the ternary alloy (W–Ni–Fe). The experimental lattice parameters of the matrix phase of alloys are in good agreement with those of the alloy systems calculated using the first-principles calculation. The lattice constants, yield strength and strength at 20% strain increase with the additions of Co and Co + Mo. The nature of theoretical stress–strain curves of systems is similar to those of the experimental stress–strain curves of typical alloys. The nitty-gritty of virtual alloy systems and the interrelated consequences resulting in closer to real alloys in terms of tensile flow curves have been discussed.