Structure–property analysis of in-situ Al–MgAl2O4 metal matrix composites synthesized using ultrasonic cavitation

Abstract

In-situ Al-MgAl 2 O 4 metal matrix composite was successfully manufactured using SiO 2 with the aid of ultrasonication. MgAl 2 O 4 particles and their clusters were identified at grain boundaries and interdendritic regions within the grain envelopes. The composite showed 2-5 fold of grain size reduction with respect to the reference alloy cast at similar conditions. The composite has shown 10% increase in yield stress and 15% increase in UTS while maintaining the ductility similar to reference alloy. CTE mismatch strengthening and grain boundary strengthening are suggested to be influencing in the improvement in mechanical properties.

Potential of an Al-Ti-MgAl2O4 Master Alloy and Ultrasonic Cavitation in the Grain Refinement of a Cast Aluminum Alloy

“…Cavitation and acoustic flows generated by the cavitation regions in a particle-populated molten metal may trigger the following events in the process under current investigation: (1) disintegration and distribution of loose TiO 2 agglomerates, (2) improved wetting and accelerated displacement reaction at particle interfaces, and (3) removal of MgAl 2 O 4 clusters and the Al 3 Ti phase from the reacted zone exposing a new diffusion zone for further reaction (event (c) in Figure 6). The mechanism is similar to the ultrasonic dispersion of in situ MgAl 2 O 4 [21] and in situ Al 3 BC [32] crystals in Al-Mg-SiO 2 and Al-B-graphite alloys, respectively.…”

“…This mechanism is very similar to the formation and clustering of MgAl 2 O 4 crystals on SiO 2 particles reported elsewhere. [21] In a parallel process, Ti atoms are released from TiO 2 and diffuse into molten Al. Fine Al 3 Ti blocks (1 to 2 lm) clustered along with MgAl 2 O 4 particles in partially dispersed agglomerates (Figures 2(c) and 5) testify for Al 3 Ti formation during the reaction.…”

“…Recent work showed that ultrasonication was capable of dispersion of in situ MgAl 2 O 4 particulates in liquid metal, while manual or mechanical stirring apparently failed to distribute fine particles in the liquid metal. [14,21] The presence of free Ti in the master alloy adds to the grain-refining effect through growth restriction. This becomes evident if one compares the results reported on the grain refinement by a similar master alloy with spinel but without Ti [14] (Figure 16) with the results reported in this article.…”

“…More recently, a significant reduction in grain size was observed in Al-MgAl 2 O 4 in situ composite, presumably caused by MgAl 2 O 4 crystals dispersed in aluminum by ultrasonic melt treatment. [21] This article reports on the manufacturing of an AlMgAl 2 O 4 concentrated master alloy and its application as a grain refiner in a commercially important cast alloy. First, the synthesis of the oxide-based grain refiner master alloy containing in situ MgAl 2 O 4 particles is described as based on the TiO 2 reaction with an Al-Mg melt assisted by ultrasonication.…”

Structure and deformation characteristics in magnesium alloy ZK51A reinforced with AlN nanoparticles

“…The procedure of composite material manufacturing should be further optimized to assure more complete distribution of particles. Apparently, the contribution to the increase of mechanical properties of the materials creates the grain boundary and particulate strengthening mechanisms [16]. …”