Abstract:The effect of adding manganese element in Zn-38Al-2.2Cu alloy on its mechanical properties and microstructures was investigated. The results show that with 0.6% addition of manganese element in Zn-38Al-2.2Cu alloy solution, part of manganese dissolves into matrix to enhance matrix, resulting in an obvious improvement of microstructures, thermal stability and thermal fatigue properties obviously. Heat resistance of the alloy is improved by high dispersity and thermal stability Mn-rich phases which is precipitated in matrix, and, the weak link of alloy grain boundary is avoided. Crack propagation and extension can be restrained by uniformly distributed Mn-rich phase with moderate size. On the contrary, bulky Mn-rich phase in continuous distribution facilitates propagation of crack.