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The present work describes the effect of Ni/Fe ratio on microstructure, tensile flow and work hardening behaviour of tungsten heavy alloys (WHAs) based on 92 wt. % W with varying Ni/Fe ratios in heat treated and swaged conditions. Evaluation of properties in the heat treated and swaged conditions reflect that the increasing Ni/Fe ratio has resulted in the enhancement of tensile as well as impact properties. Quantitative metallography and fractography have been conducted to identify the role of microstructural attributes on the failure behaviour in both the tensile and impact energy tests. The properties improvements at higher Ni/Fe ratios are due to the realisation of microstructure comprising relatively higher dissolved W in the matrix phase, higher volume fraction of matrix and reduced contiguity of W particles. True stress–true plastic strain curves of present alloys on log–log scale display two- and single-slopes in heat treated and swaged conditions, respectively. The instantaneous work hardening curves reveal the presence of three distinctive regimes (I, II and III) in heat treated and swaged conditions. The second derivatives of true stress–true plastic strain curves are parabola. [ABSTRACT FROM AUTHOR]

The present investigation deals with the processing of [(Fe0.5Co0.5)0.75B0.2Si0.05]96Nb4 bulk metallic glass (BMG) using different techniques. The maximum plate thickness for the amorphous phase formation has been found to be 1.25 mm using a conventional BMG casting technique (forced infiltration casting). For enhancing the dimension, an alternate processing route was employed to produce the BMG in the form of compacts. In this case, the dimensions are not restricted by the glass forming ability of the alloy. The process involved the preparation of amorphous ribbons using a melt spinner followed by high energy ball milling to crush the ribbons into very fine particles. The powder was then compacted in the form of pellets using spark plasma sintering technique. Density achieved was almost near to theoretical density (99%). The density was found to increase with a decrease in the particle size of glassy powder, which could be achieved by increasing the duration of high energy ball milling. The maximum densification occurred when the holding temperature was within undercooled liquid regime (∆Tx). Further increase of temperature beyond crystallization temperature (Tx) resulted in decreasing the compact density. [ABSTRACT FROM AUTHOR]

Abstract: The effect of volume fraction of primary α2 on fracture toughness of Ti–18Al–8Nb alloy, which undergoes stress-induced martensitic transformation (SIMT), was investigated. The fracture toughness of the alloy was found to decrease with an increase in volume fraction of primary α2. The results were explained on the basis of the effect of change in volume fraction of α2 on fracture toughness contributions due to SIMT as well as that due to the subsequent fracture process involving ductile fracture of the β/martensite/α2 microstructure. [Copyright &y& Elsevier]