Abstract:Based on the Mg_58.5Cu_30.5Y₁₁ alloy, 10% Ti, 10% Be and 10% Ti₇₀Be₃₀ (mole fraction) were respectively added to the alloy and samples with a diameter of 3 mm were fabricated by conventional Cu-mold casting method. The phase constituent, thermal stability and microstructure of the alloys were investigated by using X-ray diffraction, differential scanning calorimetry and scanning electron microscopy, respectively. The effects of alloying elements Ti and Be on the microstructure and mechanical properties of Mg_58.5Cu_30.5Y₁₁ alloy were discussed. The results show that CuTi phase is distributed in (Mg_0.585Cu_0.305Y_0.11)₉₀Ti₁₀ and (Mg_0.585Cu_0.305Y_0.11)₉₀(Ti_0.7Be_0.3)₁₀ alloys, while CuYBe glassy phase containing CuY crystals is embedded in the matrix of (Mg_0.585Cu_0.305Y_0.11)₉₀Be₁₀ alloy. Under uniaxial compressive loading, the largest compressive fracture strengths for (Mg_0.585Cu_0.305Y_0.11)₉₀Ti₁₀, (Mg_0.585Cu_0.305Y_0.11)₉₀Be₁₀ and (Mg_0.585Cu_0.305Y_0.11)₉₀(Ti_0.7Be_0.3)₁₀ alloys are 797.6, 952.6 and 1007.8 MPa, respectively, and the strengths are increased by about 17%, 40% and 48% compared with Mg_58.5Cu_30.5Y₁₁ alloy. The strength reliability for the three alloys is much improved according to the strength distribution region of 10 samples of each alloy.

Key words: Mg-based alloy; alloying element; Ti; Be; microstructure; strength reliability