Evolution of microstructure and mechanical properties of A356 aluminium alloy processed by hot spinning process

The evolution of microstructure and mechanical properties of A356 aluminum alloy subjected to hot spinning process has been investigated. The results indicated that the deformation process homogenized microstructure and improved mechanical properties of the A356 aluminum alloy. During the hot spinning process, eutectic Si particles and Fe-rich phases were fragmented, and porosities were eliminated. In addition, recrystallization of Al matrix and precipitation of Al Si Ti phases occurred. The mechanical property testing results indicated that there was a significant increase of ductility and a decrease of average microhardness in deformed alloy over die-cast alloy. This is attributed to uniform distribution of finer spherical eutectic Si particles, the elimination of casting defects and to the recrystallized finer grain structure.

Processing map and hot working mechanisms of Cu-Ag alloy in hot compression process

For Gu-Ag alloy, an important parameter called workability in the forming process of materials can be evaluated by processing maps yielded from the stress-strain data generated by hot compression tests at temperatures of 700-850 °C and strain rates of 0.01-10 s-1. And at the true strain of 0.15, 0.35 and 0.55, respectively, the responses of strain-rate sensitivity, power dissipation efficiency and instability parameter to temperature and strain rate were studied. Instability maps and power dissipation maps were superimposed to form processing maps, which reveal the determinate regions where individual metallurgical processes occur and the limiting conditions of flow instability regions. Furthermore, the optimal processing parameters for bulk metal working are identified clearly by the processing maps.

Effect of Different Aging Processes on the Microstructure and Mechanical Properties of a Novel Al–Cu–Li Alloy

The effects of different aging processes on the microstructure and mechanical properties of a novel Al-Cu-Li alloy have been investigated by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. It is found that the tensile properties of a novel Al-Cu-Li alloy are sensitive to aging processes, which correspond to different microstructures. σ（Al_5Cu_6Mg_2） and T_1（Al_2CuLi） phases are the major precipitates for the alloy in T6 aging condition（165 ℃/60 h）. After duplex aging condition（150 ℃/24 h ＋ 180 ℃/12 h）, σ, θ＇（Al_2Cu） and T_1 phases are detected. Only the T_1 phases can be found in the T8 state alloy（6% pre-strain＋135 ℃/60 h）. The failure modes of alloy in T6 and duplex aging conditions are dimple-intergranular fracture, while typical quasi-cleavage fracture in T8 condition.

Microstructure and properties of aging Cu–Cr–Zr alloy

The crystallography and morphology of precipitate particles in a Cu matrix were studied using an aged Cu–Cr–Zr alloy by transmission electron microscopy（TEM） and high-resolution transmission electron microscopy（HRTEM）. The tensile strength and electrical conductivity of this alloy after various aging processes were tested. The results show that two kinds of crystallographic structure associated with chromium-rich phases, fcc and bcc structure, exist in the peak-aging of the alloy. The orientation relationship between bcc Cr precipitate and the matrix exhibits Nishiyama–Wasserman orientation relationship. Two kinds of Zr-rich phases（Cu4Zr and Cu5Zr）can be identified and the habit plane is parallel to {111}Cu plane during the aging. The increase in strength is ascribed to the precipitation of Cr- and Zr-rich phase.