Aluminum alloy strengthening

[China Aluminum Industry Net] Pure aluminum has low mechanical capabilities and is not suitable for making structural parts that accept large loads. In order to improve the mechanical function of aluminum in pure aluminum to participate in certain alloying elements made of alloys, often participated in the alloying elements are copper, magnesium, chromium, zinc, silicon, manganese, nickel, cobalt, titanium and niobium, rare earth elements in a certain Participate in these alloys. After participating in these alloying elements, they are strengthened by aluminum in the following aspects.

1.Solution-hardened alloying elements participate in the formation of infinite solid solution or limited solid solution in pure aluminum, not only can obtain high strength, but also can obtain excellent plasticity and outstanding pressure processing functions. The commonly used alloying elements in solid solution strengthening in common aluminum alloys are copper, magnesium, manganese, zinc, silicon, nickel and other elements. Generally, the alloying of aluminum constitutes a limited solid solution, and binary alloys such as Al-Cu, Al-Mg, Al-Zn, Al-Si, and Al-Mn all constitute a limited solid solution, and both have a large limit of solubility. Larger solid-solution strengthening.

2. Aging strengthens the aluminum-based solid solution that can be supersaturated after heat treatment of the aluminum alloy. When the supersaturated aluminum-based solid solution is heated to a certain temperature at room temperature, its strength and hardness increase with time and elongation, but the plasticity decreases. This process is called aging. The appearance of the alloy with increased strength and hardness in the aging process is called aging strengthening or age hardening.

3. Excessive phase strengthening When the water content of the alloy elements participating in the aluminum exceeds its limit solubility, a second phase that does not dissolve into the solid solution when quenched and heated forms a so-called excess phase. The excess phase in the aluminum alloy is mostly a hard and brittle intermetallic compound. They play a role in preventing slipping and dislocation movements in the alloy, improving strength and hardness, and decreasing plasticity and resistance. The more the amount of excess phase in the alloy, the better the strengthening effect, but when the excess phase is large, the strength and plasticity of the alloy decrease due to brittleness of the alloy.

4. Refinement and Arrangement Enhancement The addition of trace element refinement in aluminum alloys is another important method for improving the mechanical properties of aluminum alloys.

In the deformed aluminum alloy, trace amounts of titanium, zirconium, niobium, tantalum, and rare earth elements are added, and they can form refractory compounds. When the alloy crystallizes, it acts as a non-self-conscious crystal nuclei, plays a role in grain refinement, and improves the strength and ductility of the alloy.

Forging aluminum alloys often participate in the transformation of microelements to refine the alloy arrangement and improve strength and plasticity. Transmutation processing has particularly important meanings for forged aluminum alloys and deformed aluminum alloys that cannot be thermally strengthened or strengthened. For example, in aluminum-silicon-forged aluminum alloys, trace amounts of sodium or sodium salts or lanthanum as metamorphic agents are used for transmutation processing, and refinement arrangements can significantly improve the plasticity and strength. Similarly, the participation of a small amount of elements such as manganese, chromium, and cobalt in the forged aluminum alloy can refine the plate-like or needle-like compound AlFeSi made of an impurity iron, improve the plasticity, and participate in the addition of trace amounts of niobium to eliminate or reduce the primary silicon and make the eutectic silicon. Refinement; particle gardens are progressing.

5. Cold deformation enhancement Cold deformation hardening is also called cold work hardening. That is, the metal data is cold deformed below the recrystallization temperature. When cold deformation occurs, the dislocation density increases within the metal and entangles with each other and forms a cell structure, preventing dislocation movement. . The greater the degree of deformation is, the more serious the dislocation tangles are, the greater the deformation resistance and the higher the strength. The degree of hardening after cold deformation varies with the degree of deformation, deformation temperature, and the nature of the data itself. When the same data is cold-deformed at the same temperature, the greater the degree of deformation, the higher the strength. Plasticity decreases with the degree of deformation.