Microstructural refinement and mechanical strengthening mechanism of the thin Al-Mg-Si alloy ribbons enhanced via melt spinning

Abstract

Effects of melt spinning process on the surface quality, microstructural evolution, phase formation, and mechanical strengthening of Al-Mg-Si alloy was investigated thoroughly. Experimental results show that the optimal nozzle diameters, nozzle-wheel gap, and wheel speed for preparing Al-Mg-Si alloy ribbons were 0.2–0.6 mm, 0.2–0.8 mm, and 1000–1400 rpm, respectively. The rapid cooling rate can be able to reach the level of 2.51 × 10⁴ K/s ∼ 1.1 × 10⁶ K/s during ribbon solidification. The average grain size of Al-Mg-Si alloy ribbon was refined to less than 10 μm. The coarsening Mg₂Si and Fe-enriched intermetallic compounds were refined to sub-micron or even nanometer scale. With the increase of wheel speeds, the size of second-phase particles became smaller and uniformly dispersed in metal matrix. The maximum microhardness of Al-Mg-Si alloy ribbon is 152 Hv, nearly 3.75 times of the conventional cast Al-Mg-Si alloy. Then, the fundamental mechanisms, responsible for the relationship between cooling rates, grain structure, texture variation, precipitates, and mechanical properties, were revealed accordingly by mathematic modelling together with multiscale characterization, and micro-nano hardness testing. This work provides some insights in preparing high-quality ribbons to architecture the bulk Al-Mg-Si alloys, which is essential for manufacturing the high precision optical and electronic components.