Recent advances in ageing of 7xxx series aluminum alloys: A physical metallurgy perspective

Microstructure and mechanical properties of a new Al–Zn–Mg–Cu alloy joints welded by laser beam

Hot deformation behavior of spray-deposited Al-Zn-Mg-Cu alloy

Cu–1.2 wt.%Cr and Cu–3.2 wt.%Cr alloys were prepared by spray forming. The as-deposited alloys were subsequently warm rolled at 300 °C with a 40% reduction and then two types of thermo-mechanical treatments were adopted to enhance the mechanical properties of the Cu–Cr alloys. The microstructural features of the Cu–Cr alloys in different thermo-mechanical processing conditions were characterized using optical, scanning electron and transmission electron microscopy techniques. The results show that the spray-formed Cu–Cr alloys exhibit a better response to heat treatment compared to the conventional casting alloys. The chromium content has a great effect on the aging behaviors of the Cu–Cr alloys. Although a higher chromium content leads to a larger volume fraction of chromium precipitates generated during the solidification, it does not cause an increase in the mechanical properties. The chromium content should be lower than 1.2 wt.%.

Investigation on the microstructure and mechanical properties of the spray-formed Cu-Cr alloys

Strain-Compensated Arrhenius-Type Constitutive Model for Flow Behavior of Al-12Zn-2.4Mg-1.2Cu Alloy

An ultra-high strength Al-11Zn-2.9Mg-1.7Cu alloy has been prepared by spray forming process. The microstructures of as-cast and as-deposited alloys have been studied. XRD analysis result shows that the phases of spray formed Al-11Zn-2.9Mg-1.7Cu alloy consist of a-Al, MgZn2, Al2Cu and Al2CuMg. T6 heat treatment process is used to strengthen the alloy. The ultimate tensile strength reach up to 810MPa, and the elongation is about 9~11%. This kind of aluminum alloy is an ideal structural material for the aerospace and automobile industries.

Research on Ultra-High Strength Al-11Zn-2.9Mg-1.7Cu Alloy Prepared by Spray Forming Process

The quenching process can produce great residual stresses in 7055 aluminum alloy plates. The main factor that affects the quenching residual stresses is the heat transfer coefficient in the quenching process. In this paper, the heat transfer coefficients of spray quenching under different spray water flows were measured by using the inverse method, and the heat transfer coefficients of immersion quenching under different water temperatures were measured by the iterative method. The heat transfer coefficient increases as the spray water flow increases while decreases as the water temperature increases. The basic differences of water temperatures/spray water flows/quenching methods are the different heat transfer coefficients. According to the heat transfer coefficients results of immersion and spray quenching, an orthogonal test was carried out to study the effects of heat transfer coefficients in different temperature regions on the quenching residual stresses. The heat transfer coefficients in the range of 100oC ~200oC have a great influence on the quenching residual stresses, especially for the heat transfer coefficient near 150oC.

Effects of Heat Transfer Coefficients on Quenching Residual Stresses in 7055 Aluminum Alloy

The finite element method (FEM) was used to study the quenching and pre-stretching residual stresses of the 7085 aluminum alloy plate, combining with experimental measurement. Quenching residual stress simulation results showed that the stress of the rolling-direction and transverse-direction in the center were 16.5MPa and 9.2MPa, respectively. The stress of the rolling-direction and transverse-direction on the surface were-33.8MPa and-40.4MPa, respectively. The quenching residual stress simulation results were in good agreement with the X-ray diffraction experimental results. As the pre-stretching ratio increases, the quenching residual stress reduction ratio increases. The ratio of 2.0~3.0% pre-stretching can effectively release the quenching residual stress in aluminum alloy plates. After 3.0% pre-stretching, the stress of the rolling-direction and transverse-direction in the center were 0.9MPa and 1.8MPa, respectively. The stress of the rolling-direction and transverse-direction on the surface were-3.6MPa and-7.1MPa, respectively. The quenching residual stress reduction ratio reached above 80%.

Numerical Simulation of Quenching and Pre-Stretching Residual Stress in 7085 Aluminum Alloy Plate

The microstructure and mechanical properties of the Al-2.24Cu-1.42Mg-0.9Fe-0.9Ni alloy were studied using optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and tensile tests. The results indicate that the microstructures of the as cast alloy involve α-Al matrix, Al/Al2CuMg eutectic structure, Al7Cu2Fe, Al7Cu4Ni and Al9FeNi compounds. The tensile test results indicate that the alloy at elevated temperature (200°C) displays superior tensile strength due to the presence of the thermally stable Al7Cu2Fe, Al7Cu4Ni and Al9FeNi compounds.

Microstructure and Mechanical Properties of an Al-Cu-Mg-Fe-Ni Alloy

An innovative spray deposition technique has been applied to produce in situ TiB2/Zn-30Al-1Cu composites. The microstructures of the spray-deposited composite were studied using optical microscopy, scanning electron microscopy, and X-ray diffraction. Both theoretical and experimental results have shown that the TiB2 particulates are formed in the microstructure. It was found that the TiB2 particles were distributed in Zn-30Al-1Cu matrix uniformly, and the TiB2 particles are about 2 μm in size. Moreover, the presence of the TiB2 particles was led to increasing of α’ phase with less 2 μm size in the composites which have a tendency to decompose to α+η structure.

Yong An Zhang

Papers

Research on Ultra-High Strength Al-11Zn-2.9Mg-1.7Cu Alloy Prepared by Spray Forming Process

Effects of Heat Transfer Coefficients on Quenching Residual Stresses in 7055 Aluminum Alloy

Numerical Simulation of Quenching and Pre-Stretching Residual Stress in 7085 Aluminum Alloy Plate

Microstructure and Mechanical Properties of an Al-Cu-Mg-Fe-Ni Alloy

Microstructure of In Situ Reaction TiB2/Zn-30Al-1Cu Composites Prepared by Spray Deposition Process