Study On Microstructure And Properties Of Sn Nanoparticles Reinforced Magnesium Matrix Composites

Particle reinforced magnesium matrix composites have some characteristics, such as isotropical mechanical properties, simple preparation process, easy machining, etc, and it is most likely to implement a low cost, large-scale production among magnesium matrix composites. In recent years, it had made many successful attempts to improve the strength and plasticity of magnesium alloy by introducing micro and nanoscale particles into matrix to prepare particulate reinforced magnesium matrix composites, and this will broaden the range of applications of magnesium alloys in the field of electronics, communications, automotive, aerospace, etc.In this paper, choosing AZ31 magnesium alloy as the matrix, Sn nanoparticles were prepared in the method of DC arc-discharge plasma and intrduced into the AZ31 magnesium alloy, Mg2Sn/AZ31 composites were prepared by Semi-Solid Stirring method, and making comparative with that Sn were introduced in the form of ingots. The influences of the introduction of Sn nanoparticles on the microstructures and mechanical properties of AZ31 magnesium alloy were studied using XRD, optical microscopy, SEM and tensile experiments at room temperature. The main conclusions are as follows:(1) Sn nanoparticles prepared in the method of DC arc-discharge plasma with size range from 40 to 80 nm exhibit a uniform distribution in the size, the Sn nanoparticles are in spherical shape and covered by an oxide layer with the thickness of about 6 nm on the surface.(2) Regardless of which kind form Sn introduced, Mg2Sn phases are formed. When Sn nanoparticles were introduced, nanoscale Mg2Sn particles could generate in the magnesium alloy substrate, however, micron-sized bulky Mg2Sn particles would generate in the matrix when Sn ingots introduced.(3) β-Mg17Al12 phases mainly distributed at grain boundary discontinuously in the form of skeleton after 1wt.% Sn nanoparticles introduced; because of the distribution of Mg2Sn phases and β-Mg17Al12 phases is overlapped, as the concent of Sn nanoparticles increased(3wt.%), the reunion of Mg2Sn nanoparticles become serious and clusters distributed at grain boundary in the form of "chain", making skeleton β-Mg17Al12 phases distributed at grain boundary continuously again.(4) The performance of AZ31 magnesium alloy were improved due to the introduction of Sn nanoparticles, as the amount of Sn nanoparticles was 1wt.%, the tensile strength and elongation increased by 35.6% and 83.6% respectively, but slightly lower than the performance of the material with lwt.% Sn ingot introduced, which could be owing to the burning loss in the process of smelting induces fewer intakes of Sn nanoparticles and Mg2Sn nanoparticles mainly existed in the form of clusters.