Investigation the Effect of Al-5Ti-1B Grain Refiner and T6 Heat Treatment on Tensile Properties of Al-8%Mg

The current study was undertaken to study the effect of different amounts of Al-5Ti-1B master alloy (0.01, 0.03, 0.05, 0.1, 0.3, 0.5, 1% weight percent) and T6 heat treatment on the microstructural evolution and mechanical properties of Al-8%Mg alloy. Microstructural assessment was carried out by optical microscopy (OM) and scanning electron microscopy (SEM) equipped with energy dispersive spectrometer (EDS) analysis. Obtained results showed that the addition of Al-5Ti-1B master alloy obviously improved the morphology of Al (α) and it was found that refined specimens have finer grains (< 250 μm) in comparison with un-refined specimen. After grain refining, the morphology of columnar alpha dendrites turn into rosette like and semi globular. The increase of Al-5Ti-1B content up to 0.1 wt. %, resulted in improvement of ultimate tensile strength (UTS) from 245 MPa to 359 MPa which shows 31% enhancement. Result of T6 heat treatment revealed a significantly enhancement on both ultimate tensile strength (UTS) and elongation values. Fractography examinations of the alloy showed an inter-dendritic fracture surface of Al-8%Mg alloy, changes to more homogenous dimples after grain refining process.