相机壳体用含RE、Sr和AlTiB压铸镁合金工艺优选及组织性能

The influences of the injection speed and injection specific pressure on the microstructure and mechanical properties of the camera body of modified AZ91D die casting magnesium alloy with RE(Ce and Y), Sr and AlTiB was studied using optical microscope (OM), X-ray diffraction (XRD), scanning electron microscope (SEM) with energy dispersive spectrometer (EDS), transmission electron microscope (TEM) and mechanical properties test. The results show that the alloy strength increases, but the elongation decreases with increasing the injection speed and injection specific pressure, and thus the optimal die-casting parameter including casting temperature of 680 ℃, injection speed of 6 m/s and injection specific pressure of 90 MPa are obtained. Co-additions of RE, Sr and AlTiB into AZ91 alloy significantly refine α-Mg grains and Mg₁₇Al₁₂ phases, and introduce fine TiB₂, Al₁₁Ce₃, Al₂Y, and Al₁₀Ce₂Mn₇ phases dispersed in the matrix, which generates a synergistic hardening effect to enhance strength. As a result, the modified alloy achieves optimal mechanical properties, such as the ultimate tensile strength of 287 MPa, yield strength of 196 MPa and elongation of 4.7%.