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

ABSTRACT

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.

KEYWORDS:

• First-principles calculation
• formation energy
• lattice constant
• stress–strain curves
• hardness

Acknowledgements

Authors are thankful to the Director, DMRL and Associate Director, Directorate of Powder Metallurgy and Material Characterisation for his encouragement. Thanks are also due to the colleagues and technical staff of powder metallurgy group and those of characterisation, modelling and machining groups of DMRL for their valuable contributions and support.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by Defence Research and Development Organisation.

Notes on contributors

Ashutosh Panchal

Ashutosh Panchal is working in Defence Metallurgical Research Laboratory, Hyderabad, India as scientist. His research interest includes Gelcasting of tungsten and its alloys, tungsten heavy alloys for penetrator applications and metallic thermal insulation material.