[China Aluminum Industry Network] Aluminum Age Hardening Principle The age hardening of aluminum alloys is a very complicated process. It depends not only on the composition and ageing process of the alloy, but also on the defects caused by alloy shrinkage in the production process, especially the vacancy. , the number and distribution of dislocations, etc. It is currently believed that age hardening is the result of segregation of solute atoms to form a hardened zone. When the aluminum alloy is heated by quenching, vacancies are formed in the alloy. During quenching, these vacancies are too late to remove and are “fixed†in the crystal. These vacancies in the supersaturated aluminum alloy solid solution furnace are mostly combined with solute atoms. Because the supersaturated solid solution is in an unstable state, it will inevitably shift to an equilibrium state. The presence of vacancies accelerates the diffusion rate of the solute atoms, thus accelerating the segregation of solute atoms. The size and number of hardened zones depends on the quenching temperature and quenching cooling rate. The higher the quenching temperature, the greater the concentration of vacancies, the greater the number of hardened zones and the reduced size of the hardened zone. The greater the cooling rate of quenching, the more vacancies fixed in the solid solution will help increase the number of hardened zones and reduce the size of hardened zones. A basic feature of precipitation hardened alloys is their equilibrium solubility as a function of temperature, ie, increasing solid solubility with increasing temperature, most heat treatable aluminum alloys meet this requirement. Factors affecting aging 1. From the effect of the residence time between quenching and artificial aging, it was found that some aluminum alloys such as Al-Mg-Si alloys were artificially aged after they were left at room temperature, and the alloy's strength index did not reach a large value. Value, while plasticity has risen. Such as ZL101 casting aluminum alloy, after quenching at room temperature for a day and then artificial aging, the strength limit is lower than the quenching immediately after the aging of 10 ~ 20Mpa, but the plasticity than the aging of the aluminum alloy has been improved. 2. The influence of the chemical composition of the alloy. Whether or not an alloy can be strengthened by ageing depends on whether or not the elements that make up the alloy dissolve in the solid solution and the degree of solid solution solubility with temperature. For example, the solid solubility of silicon and manganese in aluminum is relatively small, and aluminum alloy solid furnaces do not change much with temperature. However, although magnesium and zinc have larger solid solubility in aluminum-based solid solutions, they form compounds with aluminum. The difference between the structure and the matrix is ​​small, and the effect of strengthening is minimal. Therefore, binary aluminum-silicon, aluminum-manganese, aluminum-magnesium, and aluminum-zinc are usually not subjected to the aging strengthening treatment. And some binary alloys, such as aluminum-copper alloys, and ternary alloys or multiple alloys, such as aluminum-magnesium-silicon, aluminum-copper-magnesium-silicon alloys, etc., which have solubility and solid state phase transition in the heat treatment process, then It can be strengthened by heat treatment.