T.K. Nandy

Effect of cobalt addition on microstructure and mechanical properties of tungsten heavy alloys

The present investigation attempts to study the microstructure and mechanical behaviour of tungsten heavy alloys with different cobalt content. Alloys with 2 and 3% cobalt were synthesized using liquid phase sintering technique. The alloys were then vacuum heat treated and finally swaged. Quantitative microstructural analyses were undertaken by determining tungsten grain size, contiguity of tungsten and volume fraction of the matrix etc. Tensile results showed that the alloy with 3% cobalt exhibited inferior properties as compared to 2% cobalt alloy. Detailed microstructural and fractographic analysis were undertaken in order to understand these trends. Work hardening analysis showed the double slope behaviour of the alloys, which could be attributed to change in deformation behaviour from single phase matrix to two phase aggregate. It was also concluded that higher cobalt alloys needed further optimization in terms of thermo-mechanical treatment in order to realize their full potential in terms of mechanical properties.

Sliding Wear Properties of near β Titanium Alloy as a Function of β Solution Treatment Temperature

The present paper describes the effect of β solution treatment temperature on the sliding wear properties of near β titanium alloy (Ti-10V-4.5Fe-3Al) was examined under three different temperatures 800, 900 and 1000 °C, varying applied load 3, 6 and 9 kgf at a fixed rotational speed of 500 rpm for 16 minutes duration. The track diameter is varied 40, 80 and 120 mm in order to vary the sliding distance or sliding velocity. The sliding wear beahviour was studied using pin-on-disc apparatus against steel counter surface giving emphasis on the parameters such as weight loss as a function of sliding distance and applied load. It was observed from the results that the % weight loss is increases with increase in sliding distance and the load. It is also observed that the % weight loss increases with decreasing the β solution treatment temperature. Form the ANOVA analysis, it revealed that the β solution treatment temperature is not influencing that much on % weight loss as compared to that of load and sliding distance.