Metallographic diagram of ZG230-450 (cast state)

Mg-Zn Alloy Microstructure Characterization

The purpose of this study was to analyze the microstructure of Mg-Zn alloys produced by casting. Mg-Zn alloys are known to have the highest strength to weight ratio of all magnesium alloys, making them suitable for a variety of structural applications. The microstructures of Mg-Zn alloys form the foundation of any further development of material properties, as they determine the material’s properties.

In order to identify the microstructures of the Mg-Zn alloys, a series of cast samples of Mg-Zn alloy were produced using a ZG230-450 ZG alloy. The samples were then sectioned for metallographic analysis using a metallographic machine, before being ground and polished at several stages. After polishing, each sample was etching, which consisted of immersing the sample in a solution of H3BO3 for a specified period of time. After etching, the samples were examined using bright field microscopy.

The microstructural analysis revealed a wide variety of microstructures observed in the Mg-Zn alloy, which included equiaxed grains, lamellar colonies, dendrites, and eutectic structures. The equiaxed grains were found in the range of an average diameter of 5-8 μm, while the lamellar colonies, dendrites, and eutectic structures had larger sizes ranging from 20-50 μm. The concentrations of each microstructure were also determined in each sample. The highest concentration of equiaxed grains was observed in the ZG230-450 samples, while the highest concentration of lamellar colonies, dendrites, and eutectic structures was observed in the ZG450 samples.

The analysis of the Mg-Zn alloys revealed that the microstructures in the material were mostly composed of equiaxed grains. The size of the grains ranged from 5 μm to 8 μm , with mesh structures present in some of the samples. The lamellar colonies, dendrites, and eutectic structures, which range in size from 20 μm to 50 μm, are less common but still present in the samples. The microstructural analysis also revealed that the concentrations of each of these microstructures vary depending on the alloy composition.

In conclusion, the Mg-Zn alloys produced by casting exhibited a wide range of microstructures, with equiaxed grains being the most common and the highest concentration of lamellar colonies, dendrites, and eutectic structures being present in the ZG450 samples. The microstructural analysis of the Mg-Zn alloys allows for further study of the material’s properties, and provides insight on how the microstructure of the alloy affects performance.

The microstructure of ZG230-450 (castings) was studied. The specimens were ground on one side and the other site polished for observation. The results of the metallographic study show that ZG230-450 (castings) are martensite, ferrite and perlite microstructure.The castings are gray in color and the light gray microstructure can be clearly observed in the images. The size of the martensite is between 100 nm and 300 nm, Ferrite is more than 10 μm and Perlite is more than 5 μm. Moreover the castings appears to be relatively coarse, the distribution of the phases is relatively uniform but slightly irregular.

In addition, carbides are distributed in the castings, with the highest concentration in the martensite. The carbides are tiny and spherical in shape, about 0.2 μm in diameter. Oxygen and nitrogen have been found in the castings as well, distributed as a network around the carbides..

Additionally, ZG230-450 castings contain trace amounts of sulfur, which may have caused some sulfide inclusions to form on the surfaces of some of the microstructure phases. The sulfur levels are very low, however, and they do not appear to have an adverse effect on the performance of the castings.

Overall, ZG230-450 (castings) have a uniform and satisfactory microstructure. This microstructure provides the desired features, including good mechanical properties and good machinability,to ZG230-450 (castings).