摘要
Effects of the mischmetal addition in range of 0.4 wt.% to 1.7 wt.% on the microstructure and mechanical properties of die-cast magnesium AZ91D were investigated to improve the elevated temperature mechanical properties of the alloy by scanning electron microscopy, transmission electron microscopy, X-ray diffraction and tensile tests. The results revealed that mechanical prop- erties of die-cast magnesium alloy AZ91D-0.4%MM at 100 ℃ were near to those of die-cast magnesium alloy AZ9 ID. The ultimate tensile strength, 0.2% proof yield strength and elongation to failure of die-cast magnesium alloy AZ91D at 170 ℃ were 178, 129 MPa and 20%, respectively. In comparison, the ultimate tensile strength, 0.2% proof yield strength and elongation to faihtre of die-cast magnesium alloy AZ91D-0.4%MM at 170℃reached to 206, 142 MPa and 26%, respectively increased by 15.7%, 10% and 30%. Proper addition of mischmetal could enhance the mechanical properties at an elevated temperature, which was attributed to the formation of A1-RE phases with high thermal stability. Hence sliding of grain boundaries and cracks could be effectively hindered by A1-RE phases.
Effects of the mischmetal addition in range of 0.4 wt.% to 1.7 wt.% on the microstructure and mechanical properties of die-cast magnesium AZ91D were investigated to improve the elevated temperature mechanical properties of the alloy by scanning electron microscopy, transmission electron microscopy, X-ray diffraction and tensile tests. The results revealed that mechanical prop- erties of die-cast magnesium alloy AZ91D-0.4%MM at 100 ℃ were near to those of die-cast magnesium alloy AZ9 ID. The ultimate tensile strength, 0.2% proof yield strength and elongation to failure of die-cast magnesium alloy AZ91D at 170 ℃ were 178, 129 MPa and 20%, respectively. In comparison, the ultimate tensile strength, 0.2% proof yield strength and elongation to faihtre of die-cast magnesium alloy AZ91D-0.4%MM at 170℃reached to 206, 142 MPa and 26%, respectively increased by 15.7%, 10% and 30%. Proper addition of mischmetal could enhance the mechanical properties at an elevated temperature, which was attributed to the formation of A1-RE phases with high thermal stability. Hence sliding of grain boundaries and cracks could be effectively hindered by A1-RE phases.
基金
Project supported by Natural Science Foundation of Inner Mongolia Autonomous Region of China(2014MS0517)
