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Miniature specimen techniques viz. small-punch tests (SPT) have been carried out at room temperature in order to correlate the microstructural degradation of 2.25Cr-1Mo steel with that of SPT parameters. Microstructural degradation of this steel has been introduced as a result of thermal ageing corresponding to Larson-Miller parameters (LMP) values of 33,012, 35,402, 37,846 and 38,374. SPT parameters viz. total area and area under the region of plastic instability of the load-displacement curve have been found to decrease with an increase in LMP values. A strength parameter viz. UTS obtained using uniaxial tensile tests has also been found to decrease with an increase in LMP values. The results indicated that miniature specimen techniques viz. small-punch test could be successfully used to assess the degradation of microstructures in 2.25Cr-1Mo steel generated due to their exposure to high temperatures.

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Deformation of Titanium alloys close to optimal superplastic condition i.e. near superplastic regime of deformation leads to significant change in microstructures.VT-9 titanium alloy was used in order to find out those parameters of microstructure which are varying significantly during near superplastic regime of deformation. Tensile tests were carried out at 930°C up to fracture with a constant strain rate of 5*10-4 s-1 and a jump wise varying strain rate of 1*10-4 s-1 & 5*10-4 s-1 .The microstructural parameters of both air-cooled and water quenched portion i.e. size of alpha phase, percentages of alpha phase and parameter of non-uniaxiality of alpha phase were found to change significantly during near superplastic regime of deformation. It has been found that in the near superplastic regime of deformation percentage of α-phase decreased from 90% to 13%. As the β-transus temperature of this alloy is 970°C, this significant change in percentage of α-phase is attributed to deformation induced phase transformation. Optical microscopes, micro Vickers hardness test, XRD, FESEM have been used to characterize the microstructure of the material.