Research Contributions of Dr P R Prasad

Carried out extensive investigations relating to processing condition, microstructure and mechanical properties of rheocast Al-Cu alloys. It has been established that rheocastings and conventional castings have comparable quality and it is possible to improve the mechanical properties of single phase alloys through microstructural modifications brought about by the rheocasting process.

Developed a theoretical model for the strength of brittle matrix particulate composites. The model is based on shear lag analysis and predicts the dependence of strength on a dimensionless parameter of particle size distribution given by the ratio of the arithmetic mean to the harmonic mean of particle sizes. Experimental results confirmed the validity of the model.

Developed a model for the formation of primary particles in rheocast slurry. The model assumes that particles nucleate and grow in spherical shape and the growth is essentially mass transfer controlled. The effect of stirring has been incorporated through the effect of particle - fluid relative velocity on diffusion boundary layer thickness. The primary particle size predicted by the model agrees very well with experimental results.

The weakening effect of porosity in cast products has been theoretically analysed. The model developed predicts linear relationship between porosity and tensile strength in low porosity regime and agrees well with experimental findings.

Carried out investigations relating to the influence of composition, solutionizing temperature, ageing temperature, section thickness and cold work on the ageing response of Al-Zn alloys. The role of iron and silicon, the common impurities found in commercial grade aluminium, in modifying the ageing behaviour has also been established using excess vacancy theory.

Carried out extensive statistical analysis of experimental data on melting of metals in liquid bath. The analysis has yielded heat-transfer correlations in terms of Nusselt, Grashof and Prandtl numbers which adequately describe the experimental situations.

Dr P R Prasad

Dr Priya Ranjan Prasad, PhD FIE
169/C, Srikrishnapuri
Patna - 800001, Bihar, India