Devendra Kumar

Iron-based metal matrix composites have shown promising potential as bearing materials for various tribological applications, and hence attained the interest of the researchers. Therefore, an attempt has been made to examine the outcome of certain process variables upon the frictional properties of Fe-ZrO ₂ metal matrix composite (MMC) developed via powder metallurgy (PM). The experimental design for the applicable wear tests was carried out according to a face-centred central composite design (FCCD) utilizing response surface methodology (RSM). The tribological performance was assessed under various operating parameters of applied load (5–10 N), sliding speed (0.75–1.25 m/s) and sliding distance (200–600 m) using a pin-on-disc tribometer. The significance of the process variables upon the responses (coefficient of friction and wear rate) was investigated using analysis of variance technique. The regression equations were generated, and confirmatory experiments were executed using new parametric conditions to ensure the sufficiency of the developed models. Surface and contour plots depict the increment in coefficient of friction initially, and then decrement, while the wear rate is seen to be increasing at all levels of process variables. Moreover, the microstructures of the composite and worn surface morphology were investigated using various microstructural characterization techniques.

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SCIEPublish is an international open-access journal publishing service provider run by SCIE Publishing Limited, dedicated to supporting and inspiring scientists or institutions/societies who aspire to publish high-quality journals.

Correction for ‘Effect of a chelating agent at different pH on the spectroscopic and structural properties of microwave derived hydroxyapatite nanoparticles: a bone mimetic material’ by Vijay Kumar Mishra et al., New J. Chem., 2016, 40, 5432–5441, DOI: 10.1039/C5NJ03322E.

In the present work, Mg-Si-Al alloys were synthesized with the addition of silicon (1, 4, and 6 wt. %) and aluminum (6 wt.%) in magnesium. The objective of this study was the formation of fine Mg₂Si phase via powder metallurgy process using high energy ball milling and to investigate the microstructural, mechanical, and corrosion behavior of different composition of alloys. With increasing wt. % of Si, average grain size of Mg₂Si phase decreased and compressive fracture strain increased. According to fractographic patterns, it was revealed that AS61 alloy specimens fractured along the grain boundaries. However pure Mg, AS64 & AS66 specimens show shear plane fracture via twinning. The compressive yield strength of pure Mg and AS64 alloy were significantly affected by the twinning. The compressive yield strength of pure Mg and AS64 alloy were lower than AS61 alloy. To understand electrochemical, mechanical and structural integrity of the prepared alloys, tests for corrosion in 0.6 M NaCl solution, bulk density, porosity, and Vickers hardness were also performed.

The demand for lightweight, high specific strength alloys has drastically increased in the last two decades. Magnesium and aluminum alloys are very suitable candidate materials. Research on alloys with an Mg₂Si phase started about three decades ago. The current scenario is that magnesium and aluminum alloys containing an Mg₂Si phase are very popular in the scientific community and extensively used in the automotive and aerospace industries. Mg₂Si is a very stable phase and exhibits excellent mechanical, thermal, electrochemical and tribological properties. This paper presents a brief review of Mg–Si binary alloys, and Mg–Si–Al and Al–Si–Mg alloys. Grain refinement methods and mechanical properties have been reported on lightweight alloys containing Mg and Si. The available results show that silicon reacts with magnesium and forms an intermetallic compound with the stoichiometric formula Mg₂Si. There is in situ formation of an Mg₂Si phase in Mg–Si, Mg–Si–Al and Al–Mg–Si alloys by the diffusion or precipitation process. The morphology and size of an in situ developed Mg₂Si phase depend on the synthesis route and base metal or matrix. In the liquid metallurgy process the precipitation sequence depends on the cooling rate. The morphology of the Mg₂Si phase depends on the precipitation sequence and the mechanical properties depend on the morphology and size of the Mg₂Si phase within the alloy matrix.