The effect of heat treatment on the microstructure and properties of a hot-extruded nickel-aluminum bronze was investigated. Experimental materials were heat treated through different processes, including quenching, normalizing, aging and annealing, and their microstructure, corrosion resistance and mechanical properties were characterized. It is found that quenching causes all β phase transformed into β′ phase, however, normalizing causes β phase transformed into β′, α and κ phases. When the quenched sample is aged, fine к phase is precipitated from the as-quenched microstructure of β′ phase. Annealing causes the transformation of β′ into α and к phases. The results of mechanical property tests show that quenching, normalizing and aging improve the tensile strength and hardness of the experimental material, with a corresponding fall in elongation. Annealing raises the elongation but reduces the tensile strength and hardness. Furthermore, corrosion resistance of nickel-aluminum bronze ranks from worse to better in the following order: aged, quenched, normalized, hot-extruded and annealed. However, with the exposure time of corrosion test increasing, the difference of average corrosion rate between those nickel-aluminum bronzes turns small.
Inter-diffusion of elements between the tool and the workpiece during theturning of aluminum bronze using high-speed steel and cemented carbide tools have been studied. Thetool wear samples were prepared by using M2 high-speed steel and YW1 cemented carbide tools to turna novel high strength, wear-resistance aluminum bronze without coolant and lubricant. Adhesion ofworkpiece materials was found on all tools' surface. The diffusion couples made of tool materialsand aluminum bronze were prepared to simulate the inter-diffusion during the machining. The resultsobtained from tool wear samples were compared with those obtained from diffusion couples. Stronginter-diffusion between the tool materials and the aluminum bronze was observed in all samples. Itis concluded mat diffusion plays a significant role in the tool wear mechanism.
