Ab initio self-consistent semi-relativistic spin-polarized TB-LMTO energy band calculations have been carried out on Ni/Cu(100) multilayers, to study the in-plane as well as perpendicular to plane giant magnetoresistance (GMR) effects. The magnetic interaction energies, evaluated as a function of layer thickness, indicate that the antiferromagnetic ordering is a possible ground state for manifestation of GMR. Using the density of states at Fermi level and the Fermi velocity, GMR has been estimated as a function of the Cu spacer thickness.

In this work, we have attempted to prepare a comparative machinability study of wire electrical discharge machining of different difficult-to-machine materials, viz., stainless steel (SS) 316, H21 hot work tool steel and M42 highspeedsteel (HSS). The key features, which are compared during the analysis, are mainly material removal rate, average surface roughness, kerf width, wire consumption rate (WCR), recast layer (RL), elemental diffusion, surface morphology and micro-hardness of the machined surface. They are found to be greatly influenced by pulse energy. The pulse energy is calculated in terms of ‘specific discharge energy’. Apart from the discharge energy, the thermal conductivity of the material also plays an important role in the formation of RL and inclusion of foreign elements such as carbon, oxygen, copper andzinc in RL. H21 steel has been found to be more prone to thermal defects due to its high-thermal conductivity and high tensile residual stresses, whereas more re-solidification of foreign materials is observed in SS316 and M42 HSS due to theirhigh adhesive properties and low-thermal conductivity. But, in low-energy cutting, more uniform surfaces are observed in H21 steel in comparison with other two types of steel.