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Abstract: Commercially pure Al base short steel fiber reinforced composites were prepared by stir casting method and poured into a cast iron mould. Steel fibers were coated with copper and nickel by electroless deposition method. The density, hardness and strength of composites increased as compared to matrix alloy. The mechanical properties of these composites were measured and the results were correlated with the microstructure observation. It was found that copper-coated short steel fiber reinforced composites show considerable improvement in strength with good ductility because copper form a good interface between Al matrix and short steel fiber. Nickel-coated steel fiber reinforced composites showed improvement in strength to a lower extent possibly because of formation of intermetallic compound at the interface. The improvement in strength with uncoated fibers and nickel-coated fibers is on the lower side because of formation of brittle intermetallic compounds like Fe2Al5 and FeAl3. Fracture surface of tensile specimen was examined under SEM, which revealed a ductile fracture. Copper coating on steel fiber improved the strength properties while retaining a high level of ductility due to better interface bonding. [Copyright &y& Elsevier]

Abstract: The present investigation is on the wear behaviour of Al–2Mg base 5wt% short steel fiber reinforced composites. The composites were prepared through stir casting. The short steel fibers were coated with copper and nickel by electroless deposition process for better fiber distribution and interface bonding to improved wear properties. Dry sliding wear behavior of cast Al–2Mg base composites has been investigated using a pin-on-disc wear-testing machine. The applied load was varied in the range of 10–40N. The volumetric wear loss increased with increasing sliding distance and applied load. Composites with 5wt% copper coated fibers considerably reduced the wear rate and coefficient of friction compared to matrix alloy. The wear rate increased with increasing applied load. Amongst the investigated composites, the copper-coated steel fiber reinforced composite showed maximum improvement in wear rate due to better interface bonding. The Al–2Mg base composites containing 5-wt% fibers exhibited a transition from mild to severe wear depending on sliding distance and applied load. Two modes of wear have been identified to be operative based on the detail examination of wear surface, wear debris and analysis of the wear data. The transition from mild wear to severe wear was influenced by the applied load, sliding distance, hardness and strength of the pin material adjacent to the contact surface as well as by the strain induced shear stress created by applied loads. [Copyright &y& Elsevier]

Abstract: This investigation examines low temperature tensile deformation behavior of AISI 304LN stainless steel along with synergistic analysis of acoustic emission signals. The tensile tests are done at a range of temperatures starting from 283K till 223K. The fracture surfaces of the broken specimens are investigated using scanning electron microscope. The amount of deformation induced martensite is measured using a feritscope. The obtained results reveal that with decrease in test temperature, both strength and ductility increase. The increase in strength and ductility with decreasing temperature is explained in terms of void morphologies and formation of deformation induced martensite. The rapid increment in strength and ductility at 223K is associated with the burst of martensitic transformation at that temperature; which has been clarified from acoustic emission signals. An additional initiative has been taken to model the evolution of martensite formation from the observed cumulative emission counts using a non linear logarithmic functional form. The fitted curves from the recorded acoustic emission cumulative count data are found to be better correlated compared to earlier obtained results. However, at 223K normal non-linear logarithmic fit is not found suitable due to presence of burst type signals at intervals, therefore; piecewise logarithmic function to model acoustic emission bursts is proposed. [Copyright &y& Elsevier]

Abstract: The low cycle fatigue behaviour of titanium alloy IMI 834 was comparatively studied in bare condition and with titanium aluminide coating, at 600°C in air, for compressor disc of aero engines. At higher values of total strain amplitudes (Δɛ t/2), coated alloy has longer fatigue life as compared to the bare alloy which appears to be due to load shifting to the coat, but at lower values of Δɛ t/2, coating seems to have no effect on fatigue life. Coating adheres well to the substrate and offers resistance to cyclic plastic deformation and hence is beneficial. [Copyright &y& Elsevier]