Interfacial structure of nano WC powder cold planting via laser shock peening onto light metal surfaces

Abstract

Light metal alloys are extensively used in many industries like aerospace, transportation and shipping industry as structural materials due to their lightness, high strength weight ratio and good corrosion resistance. This can reduce the material/energy consume and recycle the materials for environment protection. However, the surface hardness and wear resistance of aluminium and magnesium alloys are usually poor, which limits their service lifetime for applications. There are some available processes being capable to improving the surface properties of the light alloys. However, almost all of these processes are thermal process which may induce lighter element burning, porosity and cracking. Nano-materials have strong acoustic, optic, electric, magnetic and thermodynamic characteristics because of their quantum size and surface effect. It can play an important role in hardfacing the light metal alloys.Combining the unique characteristics of nano powers and laser shock peening, we have developed a novel process: nano powder cold planting via laser shock peening with pre-coated nano powders (refer to NPCP/LSP) onto light metal surfaces. The nano powders are planted into the near surface layer of the light metal alloys by the very high pressure (up to Giga or even tens of Giga Pascal) induced by the laser shock peening process. Light alloy surfaces can be dramatically enhanced by the combined strengthening of the nano powders and also the laser shock peening process. This is not a thermal process which can effectively avoid the shortcomings associated with a thermal process. The unique features of the nano-powders can be integrated into the near surface layer of the light alloys with good combination.This paper reports our continusous research on NPCP/LSP, focusing on the interfacial structure of nano powders planted onto the light alloy surface, the combination of nano powders with the substrate, the interface bond between the nano particles and the matrix. The analysis on interfacial structure will help to clarify NPCP/LSP process and principle, explain and evidence the significant improvement on the surface hardness, wear resistance, and tribologocal properties by NPCP/LSP process.Light metal alloys are extensively used in many industries like aerospace, transportation and shipping industry as structural materials due to their lightness, high strength weight ratio and good corrosion resistance. This can reduce the material/energy consume and recycle the materials for environment protection. However, the surface hardness and wear resistance of aluminium and magnesium alloys are usually poor, which limits their service lifetime for applications. There are some available processes being capable to improving the surface properties of the light alloys. However, almost all of these processes are thermal process which may induce lighter element burning, porosity and cracking. Nano-materials have strong acoustic, optic, electric, magnetic and thermodynamic characteristics because of their quantum size and surface effect. It can play an important role in hardfacing the light metal alloys.Combining the unique characteristics of nano powers and laser shock peening, we have developed a novel p...