A1 3 Zr/A356 Composite was prepared by in-situ reaction of K 2 ZrF 6 powder and cast aluminum A356 melt at different temperatures (710°C, 750°C, 770°C, 790°C). The effect of different melting temperature on the morphology of Al 3 Zr particles was studied, and the sliding friction and wear properties of the composites were studied by wear test. It can be seen from the x-ray diffractometer (XRD) that the prepared composite material consists of A1 3 Zr and ɑ-Al, and also has a small part of the aluminum-silicon eutectic phase; SEM analysis shows that the particles of in-situ reinforced phase are fine, With the increase of temperature, the morphology of A1 3 Zr reinforced phase changed from block to needle and strip, and the particle distribution of the reinforced phase was uniform and well dispersed in the matrix at 750°C. TEM experiments show that the reinforced phase exists at 750°C and has a good combination with the matrix, which plays a very good role in particle reinforcement Friction and wear experiments show that the different preparation temperature results in different phase morphology. The reinforced phase particles existing on the surface of composites at 710°C and 750°C bear most of the friction, so the friction coefficient of the composites is larger at these preparation temperature, and the main wear modes are oxidation wear and abrasive wear. The friction coefficient of the composites prepared at 770°C and 790°C is small, and the wear modes are mainly delamination wear and oxidation wear. When the preparation temperature is 750°C, the wear resistance of the composites is the best.
Al 3 Zr+AA6082 particulate reinforced aluminum matrix composites were prepared in situ at 750 °C, 780 °C and 810 °C by the reaction of K 2 ZrF 6 salt-coated powder with AA6082 melt under electromagnetic stirring. Linear friction and wear tests at room temperature were carried out on three kinds of Al matrix composites prepared at different temperatures. The test result were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), EDS, confocal laser scanning microscopy and transmission electron microscopy (TEM). The results show that the Al 3 Zr phase is formed at 750 °C, 780 °C and 810 °C and small. Under the same load, the wear volume of the composites prepared at 780 °C and 810 °C is larger than that of the aluminum matrix composites prepared at 750 °C. The main wear mechanisms of aluminum matrix composites prepared at various temperatures under different loads are adhesive wear, and the wear volume increases with the increase of load. The average friction coefficient of the three composites under different loads is about 0.5, and the friction performance is stable.
Herein, in situ Al3Zr + 6082Al aluminum matrix composite sheets subjected to ultrahigh‐speed friction stir welding (FSW) at welding and stirring‐head rotation speeds of 200 mm min−1 and 11 000, 13 000, or 15 000 rpm, respectively, are focused on. X‐ray diffraction, electron microscopy, energy‐dispersive spectrometry, microhardness testing, and tensile testing are used to investigate the microstructures and mechanical properties of the welds. The weld nugget zone (NZ) of the high‐speed FSW joint of the Al3Zr + 6082Al matrix composite sheet comprises mainly equiaxed recrystallized grains, the thermomechanically affected zone comprises equiaxed recrystallized grains and elongated plastically deformed grains, and the heat‐affected zone comprises recrystallized grains. Results show that the FSW joint formed at 13 000 rpm and 200 mm min−1 is extremely well formed and has a compact and uniform structure. The microhardness of the 13 000 rpm FSW joint is highest at an NZ hardness and tensile strength of 128.08 HV and 153.7 MPa (87% of that of the base metal), respectively.
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