X-ray diffraction study of W + (Ni, Fe, Co) powder compositions

A method of sintering tungsten nanopowders with individual components (added or deposited), e.g., Ni, Fe, Co, is used in the production of new high-strength nano- and fine-grained heavy tungsten alloys. The presence of such components facilitates conditions for traditional liquid-phase sintering of tungsten-based powders or for solid-phase sintering using spark plasma sintering technology. We present the results of an X-ray diffraction study of binary systems of W + (Ni, Fe, Co) powders containing 95 – 99.5 wt.% of tungsten. The evaluation of the reproducibility of the results demonstrated that the intensity of the X-ray diffraction maxima of the studied phases is replicated with an accuracy of at least 3% for the main phase (tungsten) and at least 6% for the additive (specifically, nickel). It has been demonstrated that in analysis of powders using X-ray diffraction the sensitivity to nickel, iron and cobalt is 0.5, 1, and 3 wt.%, respectively. The obtained estimates are compared with the value calculated proceeding from structural and crystallographic phase data. The impracticality of using structural theoretical relations for quantitative phase analysis of W – Fe and W – Co systems is demonstrated due to the significant absorption of Cu K α radiation by iron and cobalt. The results obtained can be used to improve the technique of X-ray diffraction control of the phase composition of high-strength nano- and fine-grained heavy tungsten alloys.