STUDY ON ELEVATED TEMPERA-TURE MECHANICAL PROPERTIES OF AM50HP WITH ND

摘要

＜正＞ Effects of Nd on the mechanical properties of die casting magnesium alloys AM50 are investigated. It is found that the ultimate tensile strength, yield strength and elongation of the AM50 alloy at elevated temperatures up to 200 ℃ increase with an addition of Nd. Generally, the most significant improvement in the tensile properties is attained at 100 ℃. The presence of Mgl2Nd is proved by X-ray diffraction. Microstructural observations reveal that the addition of Nd can lead to the dispersion-strengthening. Due to the presence of Mgl2Nd, the sliding of grain boundaries is restrained and the strength of the alloy is enhanced. It can be seen from the tensile fractographs that the fracture surfaces exhibit the mixed fracture characteristics, and less brittle fracture is observed with increasing the temperature. Quasi-cleavage fracture is thought as the main fracture mode. TEM observations expose the formation of dislocation network, slip lines and dislocation pile-ups.