We have performed a detailed investigation of the molecular beam epitaxial growth and characterization of InN nanowires spontaneously formed on Si(111) substrates under nitrogen rich conditions. By employing an in situ deposited thin (approximately 0.5 nm) In seeding layer prior to growth initiation, we have achieved, for the first time, non-tapered epitaxial InN nanowires, which exhibit record narrow spectral linewidths of 14 and 40 meV at 5 K and 300 K, respectively. Detailed studies confirm that the wires are nearly free of dislocations and stacking faults. The achievement of non-tapered, nearly homogeneous InN nanowires also enables, for the first time, the derivation of the band gap of InN directly from PL spectroscopy in the temperature range of 5-300 K.

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Maraging steels are a group of martensitic steels possessing ultra high strength along with good fracture toughness. Conventional 18 wt.% Ni maraging steels are very costly in part because of expensive alloying elements such as Ni and Co . Replacement of Ni by cheaper elements like Mn has been studied by many researchers. Fe – Ni – Mn ternary alloys show good age hardenability formation of nanometer sized intermetallic precipitates such as f.c.t. θ- NiMn during aging. These alloys are ductile in the solution annealed condition but suffer from severe embrittlement after aging by intergranular fracture along prior austenite grain boundaries (PAGBs). Discontinuous coarsening of grain boundary precipitates was found as the main source of embrittlement. In this paper the effect of cold rolling on the mechanical properties of Fe -10 Ni -7 Mn steel was investigated. Cold rolling for 20%, 40%, 60%, 80% and 90% were carried out on a solution annealed material with subsequent aging at 753 K. Improvements in the tensile properties of the as-deformed and aged alloys were found. Substantial improvement is found at thickness reductions larger than 60%, where severe plastic deformation and ultrafine grain formation are realized.

Fe-Ni-Mn martensitic steels show excellent age hardenability but suffer from embrittlement after aging. Discontinuous coarsening of grain boundary precipitates was found as the main source of embrittlement. Effect of cold rolling and equal channel angular pressing on the mechanical properties of an Fe-10Ni-7Mn steel was investigated. Cold rolling for 20%, 40%, 60%, 80% and 90% and equal channel angular pressing for four passes through the Bc route were carried out on a solution annealed material with subsequent aging at 753 K. Hardness measurement, tensile test and scanning electron microscopy were used to study mechanical properties and microstructural features of the as-deformed and aged alloys. Improvement in tensile properties of the as-deformed and aged alloys was found. A tensile strength of about 1840 MPa along with 3% elongation were determined for cold rolled by 90% thickness reduction and aged alloy, while conventional steel shows a premature fracture stress of 820 MPa with zero ductility. It was also indicated that after heavy cold rolling ductility increases in comparison to the equal channel angular pressed and aged alloy.

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