Defence Metallurgical Research Laboratory

About: Defence Metallurgical Research Laboratory is a facility organization based out in Hyderabad, India. It is known for research contribution in the topics: Microstructure & Alloy. The organization has 1208 authors who have published 2662 publications receiving 51663 citations.

Effect of process variables on the structure, residual stress, and hardness of sputtered nanocrystalline nickel films

Abstract: Nanocrystalline nickel films of about 0.1 μm thickness grown by sputtering with and without substrate bias possessed average grain sizes of 9–25 nm. Variation in substrate bias at room and liquid nitrogen temperature of deposition strongly affected grain structure and size distribution. Qualitative studies of film surfaces showed variation in roughness and porosity level with substrate bias and film thickness (maximum of 8 μm). The films had tensile residual stress, which varied with deposition conditions. The hardness values were much higher than those of coarse-grained nickel but decreased with an increase in the film thickness because of grain growth.

Constitutive modeling and fracture behavior of a biomedical Ti–13Nb-13Zr alloy

Abstract: The dynamic compression tests were performed at various strain rates (001, 1700, 2700 and 3500/s) and temperatures (25, 200, 400 and 600 °C) for a biomedical Ti–13Nb-13Zr alloy Based on experimental data, constitutive models were established using the Modified Johnson-Cook (J-C) model, Modified Khan–Huang–Liang (KHL) model and Artificial neural network (ANN) model, respectively The new modified J-C model considers the coupled effects of strain hardening, strain rate hardening and thermal softening In this work, a radial basis function artificial neural network (RBF-ANN) model was also developed to predict the high strain rate flow curves of Ti–13Nb-13Zr alloy The results demonstrate that the flow behavior of Ti–13Nb-13Zr alloy is considerably influenced by the strain rate and temperature The modified KHL model and ANN significantly enhance the predictability The deformation behavior represented by dynamic recrystalization (DRX) and the instability flow has been discussed with reference to microstructural evolution during high strain rate compression The validation of the developed constitutive model is embedded in the finite element analysis (FEA) to perform numerical simulations with ABAQUS/Standard to obtain the charpy impact energy

Strength of hot pressed ZrB2–SiC composite after exposure to high temperatures (1000–1700 °C)

Abstract: Residual strength (room temperature strength after exposure in air at high temperatures) of hot pressed ZrB2–SiC composites was evaluated as function of SiC contents (10–30 vol%) as well as exposure temperatures for 5 h (1000–1700 °C). Multilayer oxide scale structures were found after exposures. The composition and thickness of these multilayered oxide scale structure was dependent on exposure temperature and SiC contents in composites. After exposure to 1000 °C for 5 h, the residual strength of ZrB2–SiC composites improved by nearly 60% compared to the as-hot pressed composites with 20 and 30 vol% SiC. On the other hand, the residual strength of these composites remained unchanged after 1500 °C for 5 h. A drastic degradation in residual strength was observed in composites with 20 and 30 vol% SiC after exposure to 1700 °C for 5 h in ZrB2–SiC. An attempt was made to correlate the microstructural changes and oxide scales with residual strength with respect to variation in SiC content and temperature of expsoure.