The Study Of High Temperature Mechanical Properties Of High Purity Al-3Fe Alloys

Al-Fe alloys have good heat resistance, abrasion resistance and corrosion resistance, and elements of Al and Fe is the most abundant elements in the crust, so they will have broad development prospects. But their applications have been limited for Al3Fe and other intermetallic were often acicular distribution in Al-Fe alloy. In this work, we use Al-3Fe alloy as study objects, optical microscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and universal testing machine were employed to investigate the superplasticity and high temperature mechanical properties of Al-3Fe alloy sheets and analyse the formation mechanism of the microstrcture. The main results are as follows:(1) The edge of microstructures in as-cast Al-3Fe alloy consisted of well-developed a-Al dendrites and eutectic structures in dentritical clearance. The closer to centre zone the more compact of eutectic structures. At the center he rich-iron phases was diffusely distributed in aluminum matrix.(2) YS of as-cast Al-3Fe alloy was70.24MPa, UTS of as-cast Al-3Fe alloy was139.46MPa and elongation was24.66%. With the increment of test temperature, the YS and UTS declined, elongation increased. At100℃,150℃,300℃, strength of as-cast Al-3Fe alloy decrease slower. And compared to other non-heat-treatable aluminium alloys, the strength of Al-3Fe showed obvious advantages.(3) After hot rolling and cold rolling and annealing iron rich phases dispersively distributed in aluminum matrix. A majority of grain boundaries were small angle grain boundaries. The grain size was about0.5μm and the second phase parcticles size ranged from50nm to100nm. Most of iron rich phase particales were found distributed around grain boundaries.(4) After hot rolling at450℃YS of Al-3Fe alloy was136.84MPa, UTS was174.08MPa, elongation was24.77%at room temperature; After hot rolling at550℃YS of Al-3Fe alloy was145.46MPa, UTS was179.52MPa, elongation was16.0%at room temperature; The YS and UTS of hot rolled alloys declined with increment of test temperature, however the elongations increased with increment of test temperature at100℃,150℃,300℃.(5) Superplasticity was not shown in Al-3Fe alloy after no matter after cold rolling nor hot rolling.