Negative effects of zinc on aluminum bars
When the content of Mg exceeds that required for the formation of Mg/Zn2 phase, the stress corrosion cracking resistance is the highest when the ratio of zinc and magnesium is about 2.7.Such as adding copper elements on the basis of Al-Zn-Mg to form Al-Zn-Mg-Cu alloy, the strengthening effect is the largest in all aluminum alloys, and it is also an important aluminum alloy material in the aerospace industry, aviation industry and power industry.
When the content of Mg/Zn2 increases from 0.5% to 12%, the tensile strength and yield strength can be obviously increased.
The equilibrium phase diagram of Al-Zn alloy shows that the solubility of zinc in aluminium is 31.6%, while the solubility of aluminum decreases to 5.6% at 125 when the rich aluminum fraction reaches 275.When zinc is added to aluminum alone, the strength of aluminum alloy increases very much under the condition of deformation, and the tendency of stress corrosion cracking exists at the same time, which limits its application.The addition of zinc and magnesium to aluminum forms a strengthening phase, Mg/Zn2, which has an obvious strengthening effect on the alloy.
