GD is generally used to improve the high temperature strength and microstructure of cast magnesium alloy, and also to improve the room temperature properties of the alloy.
When rare earth GD is added to az21 cast magnesium alloy, the main phases are α – Mg and al2gd. With the increase of Gd, the size and quantity of al2gd increase. When the amount of GD reaches 3.5%, the number of mesophase increases, and the number of semi continuous or continuous precipitated mesophase near the grain boundary increases. The high temperature tensile strength and yield strength of the alloy increase with the increase of GD. When the GD content reaches 2%, the tensile strength and yield strength of the alloy reach 148 and 90 MPa respectively at 200 ℃. The tensile strength and yield strength of the alloy decreased with the increase of GD. At 200 ℃, the alloy shows high plasticity, but with the increase of Gd, the elongation of the alloy does not decrease with the increase of GD. When the GD content is 3.5%, the creep of 70 h is only 1.2%, which is 13% of the creep of the base alloy. Therefore, the addition of rare earth GD can significantly improve the creep resistance of the base alloy.