Effect of Rare Earth Upon As-Cast Microstructure and High Temperature Performance of ZA40 Alloy
In testing comparison, this study is made on the modification effect of 0.05 wt.% La-rich rare earth (RE) upon as-cast microstructure, mechanical properties of materials at high temperatures (100, 150, 200°C) and wear resistance under different temperatures (100and 200°C) of ZA40 alloy containing Si. The addition of RE shows that it can not only effectively refine Al-rich and Cu-rich phase, but also reduce the amount of needle-like eutectic silicon, and then make the size of massive primary silicon phase smaller. Thus, there are the improvement of strength, ductility and wear resistance of materials at high temperature. The analyses are also conducted on the mechanism of underlying RE elements.
Effects of stabilizing heat treatment on microstructures and creep behavior of Zn–10Al–2Cu–0.02Ti alloy
Abstract The microstructures of as-extruded and stabilizing heat-treated Zn–10Al–2Cu–0.02Ti alloys were observed by scanning electron microscopy, transmission electron microscopy, electron probe microanalysis and X-ray diffraction analysis techniques. The change in structure after heat treatment and its effects on room temperature creep behavior were investigated by creep experiments at constant stress and slow strain rate tensile tests. The results show that after stabilizing heat treatment ((350 °C, 30 min, water-cooling)+(100 °C, 12 h, air-cooling)), the amount of α+η lamellar structure decreases, while the amount of cellular and granular structure increases. The heat-treated Zn–10Al–2Cu–0.02Ti alloy exhibits better creep resistance than the as-extruded alloy, and the rate of steady state creep decreases by 96.9% after stabilizing heat treatment.
The behaviour of block-like residual austenite of 52100 steel in sliding wear
Abstract The behaviour of the block-like residual austenite (Ar) of 52100 bearing steel in sliding wear was investigated on the Amsler testing machine. The effect of different residual austenite content on its wear volume was also compared. Experimental results showed that for the steel with lower Ar content, after conventional quenching and tempering heat treatment, the wear mechanism is abrasive, while for the steel with higher Ar and without carbides, after austempering, the wear mechanism changes to delamination. Owing to its distinctive stability, the effect of residual austenite on wear behaviour was also different.