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This paper describes the microstructure, hardness, and wear characteristics of cast aluminium-silicon alloy produced by a stir-casting technique. A hypoeutectic (Al-7% Si-0.8% Cu) alloy was cast under different stirring speeds. The stirring of semi-solid metal (SSM) slurries was performed under continuous cooling conditions from liquidus temperature. Wear characteristics of the alloys under investigation were studied using a pin-on-flat wear system over a range of normal loads (10-40 N) at constant average sliding speed (0.2 m/s) against cast iron and stainless steel counter surfaces. Stir-casting resulted in a material with higher microhardness and lower wear rates than conventional cast alloy. Both the stir-cast and conventional cast alloy showed higher weight loss against the stainless steel compared with that against the cast iron counter surface. Optical microscopy of the conventional cast and stir-cast alloys showed that the stir-casting results in spheroidization and refinement of primary alpha aluminium and modification of eutectic silicon. The scanning electron microscopy of wear surfaces was carried out to investigate the mode of wear. Attempts were made to establish the structure property relationship.

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An experiment was conducted in the laboratory to evaluate the effect of herbicides on beneficial and pathogenic microorganisms. Eighteen treatments included six herbicides at three different doses viz., cyhalofop-butyl (80, 160 and 240 ppm), cyhalofop-butyl + penoxsulam (150, 300 and 450 ppm), bispyribac-sodium (25, 50 and 75 ppm), fenoxaprop-p-ethyl (60, 12 and 180 ppm), carfentrazone-ethyl (20, 40 and 60 ppm) and chlorimuron-ethyl + metsulfuron-methyl (4, 8 and 12 ppm) evaluated on beneficial microbial bioagents (Trichoderma viride and Pseudomonas fluorescens) and pathogenic microorganisms (Rhizoctonia solani, Pyricularia oryzae and Xanthomonas oryzae pv. oryzae). Results revealed that bispyribac-sodium and cyhalofop-butyl + penoxsulam had greatest inhibitory effect on pathogenic microorganisms Rhizoctonia solani (47.76 and 54.40%) and Pyricularia oryzae (49.07 and 61.12%), but showed no effect on Xanthomonasoryzaepv. oryzae, and were less harmful to biocontrol agents Trichoderma viride and Pseudomonas fluorescens at recommended doses, which were effective in control of broad spectrum of weed flora in rice ecosystem.

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