Enhancing the microstructure and mechanical properties of Si3N4–BN strengthened Al–Zn–Mg alloy hybrid nano composites using vacuum assisted stir casting method

Abstract

The present work investigates the microstructural and mechanical properties of nano-Si3N4-BN hardened Al–Zn–Mg alloy hybrid nanocomposites synthesized by a vacuum-assisted stir casting process using different weight fractions. The microstructural analysis is performed using an optical microscope and the morphology studies were characterized using SEM analysis. The B117 salt spray test has been used to analyze the corrosion tests on hybrid nano composites. The microstructure evaluation revealed that nano-reinforcing particles are uniformly distributed in the matrix alloy without residual pores forming in the matrix alloy and shows the occurrence of intradendritic grains along the grain boundaries. Morphology analysis of synthesized Aluminium alloy hybrid nanocomposites illustrates that ceramic hard particles cannot be resolved and appear as fine globular species at high temperatures and its crystalline size of an average 44.9 nm has been observed. Owing to reduction in grain size and enhanced grain refinement the tensile and compressive strength of hybrid nano composites significantly increased in comparison with as cast Al–Zn–Mg alloy. The presence of Al2Cu forms as an intermetallic phase, impeding dislocation progression and it acts as corrosion resistant of developed hybrid nano composites.

Keywords

• Al–Zn–Mg alloy
• Silicon nitride
• Boron nitride
• Vacuum assisted stir casting
• Salt spray test
• Microhardnes