Effect of laser surface melting on nanoparticles dispersion and tensile properties of in-situ nano-ZrB2p/6061Al composite

Abstract

Laser surface melting (LSM) were successfully applied in in-situ 10 vol% ZrB2(np)/6061Al composites. Formation of nano-sized ZrB2 phase is confirmed by FESEM, EDS and HRTEM. Due to the minimization of porosity defects, one-way laser scanning is evaluated as optimum scan route strategy. After LSM, nanoparticle aggregations in composites are largely eliminated by melt vortex and matrix grain growth pushing force. Nanoparticles are uniformly dispersed near matrix grain boundaries and agglomerations showed an explosive orientation dispersion. After LSM, the average matrix grain size decreased by 87.5% to 3.4 μm. Nanoparticle dispersion uniformity and toughness of composites are proportional to laser power density. Both strength and elongation are enhanced as the matrix grain refinement and better uniformity of the nanoparticle dispersion after LSM. When LSM for 420 NW/mm2 was performed, the optimal improvements of tensile strength and elongation are 33.54% and 72.51% respectively.

Keywords

• ZrB2(np)/6061Al composite
• Laser surface melting
• Nanoparticle aggregations
• Explosive orientation dispersion