A Comparative Study on Microstructure, Mechanical Property, and Electrical Conductivity of Al-7Si-0.6Mg Alloy Produced by High Pressure Die Casting and Semisolid Die Casting

Abstract:

Two casting technologies were introduced to fabricate the Al-7Si-0.6Mg alloy, including high pressure die casting (HPDC) and semi-solid die casting (SSM). The microstructure and mechanical property were studied by optical microscopy (OM), scanning electron microscopy (SEM), X-Ray diffraction (XRD), microhardness and tensile test. The electrical conductivity was also introduced to evaluate the thermal conductivity of the alloys. Results show that the as-cast microstructure of the HPDC alloy and SSM alloy both consists of primary α-Al, eutectic Si and Mg₂Si phase. The primary α-Al phase in HPDC alloy possesses fine equiaxed dendrite structure with an average grain size of 29.4 μm. While the SSM alloy forms abundant coarse and globular structure α-Al phase, and the average grain size reaches 98.9 μm. This is because of the lower cooling rate during slurry preparation promotes the formation of a relative coarse microstructure in the SSM alloy. Furthermore, the increased content of eutectic Mg₂Si phase was also detected in the SSM alloy. Therefore, the average yield strength and ultimate tensile strength decreases from 148 MPa and 275 MPa of the HPDC alloy to 140 MPa and 254 MPa of the SSM alloy, respectively. However, the elongation and electrical conductivity of the SSM alloy both increases from 5.8±1.3% and 20.0±0.1 MS/m of the HPDC alloy to 7.5±1.2% and 20.6±0.1 MS/m, respectively.

• Periodical: Solid State Phenomena (Volume 347)
• Pages: 53-59
• DOI: https://doi.org/10.4028/p-e9tflJ
• Online since: August 2023
• Authors: Jian Feng*, Shu Zhu, Song Chen, Yu Dong Sui, Da Quan Li
• Keywords: Electrical Conductivity, High Pressure Die Casting, Mechanical Properties, Microstructure, Semisolid Die Casting

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