Mg-5Sm-xGd Alloys and Abnormal Temperature Effect of Tensile Strength
The microstructure and mechanical properties of aged Mg-5Sm-xGd(x=1,2,3,4)alloys were stud-ied by optical microscopy,scanning electron microscopy,X-ray diffraction and electron tensile tests.The results show that the aged alloys are mainly composed of a-Mg matrix and rare earth phases Mg5Gd and Mg41Sm5 located in the dispersed in the grain,and the number of rare earth phases gradually increases with the increase of Gd content.Gd content can change the grain size,and the grain size decreases first and then increases with the in-crease of Gd content,and the grain size is the smallest when the Gd content is 3％.The tensile strength increas-es with increasing temperature,and has an abnormal temperature effect of tensile strength.At the same tempera-ture,the tensile strength is the highest at 3％Gd content,and increases with temperature,reaching a peak of 229.9 MPa at 300 ℃.The yield strength of the alloys increases with the increase of temperature,first increases,then decreases,and then increases with the increase of Gd content.The yield strength reaches the maximum when the Gd content is 3％and the tensile temperature is 300 ℃.The tensile fracture mode is mainly brittle fracture,and gradually changes to ductile fracture with increasing temperature.The abnormal temperature effect of tensile strength of may be related to changes in the lattice constant,grain size,and second phase.
Mg-5Sm-xGd alloymicrostructuretensile strengthabnormal temperature effect
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