A MICROSTRUCTURAL AND MECHANICAL PROPERTY STUDY OF AN AM50 HPDC MAGNESIUM ALLOY

As the need for weight saving and fuel economy has increased, so has the interest in using Aluminum-Manganese (AM) Magnesium alloys. A thorough examination of the existing literature found several competing conclusions on how elongation and microstructure correlate; therefore a study was performed on a high-pressure die cast (HPDC) AM50 alloy. This study focused on understanding the relationship between microstructure and mechanical properties in test bars manufactured from a complex-shaped test casting. The results from this study found a high degree of variability in the resulting tensile properties, especially in the elongation-to-failure data. To understand the role of microstructure on properties, an extensive analysis of the microstructures was performed. No difference in cell size through the sample cross-section was observed. Externally solidified cells (ESCs) were present in large numbers; however, no correlation could be determined between the location of the samples and the size and number of the ESCs. Porosity distribution was random across the sample cross-section. Examination of the fractures surfaces indicated that the fracture did not preferentially occur along the Mg17Al12 eutectic in the AM50 alloy.