Mechanical behavior of AZ31/Al 2 O 3 magnesium alloy nanocomposites prepared using ultrasound assisted stir casting

Influence of ultrasonication power on grain refinement, mechanical properties and wear behaviour of AZ91D/nano-Al2O3 composites

“…On the contrast, the size and structure of brittle cleavage and micro dimples are different in the images. For untreated composite ( figure 9(a)), the cleavage step size is comparatively large and also the presence of flat rough surface indicate the prominence of brittle fracture over ductile fracture [10]. For UST assisted composites the SEM micrographs (figures 9(b)-(d)), show the presence of more micro dimples which indicates the prominence of ductile deformation [21,22].…”

“…The strengthening contribution of reinforcements in the matrix is due to various strengthening mechanisms such as load transfer strengthening (Δ LT ), Orowan strengthening (Δ ORO ) and coefficient of thermal expansion mismatch strengthening (Δ CTE ). Among, load transfer strengthening contribution is relatively small when compared to the other two mechanisms and is negligible in the case of nanocomposites due to the low volume fraction [10]. The CTE mismatch strengthening occurs due to the residual plastic strain phenomenon in the composites due to the large difference in thermal expansion coefficients between the matrix and reinforcement.…”

“…The critical size of the alumina particles in magnesium matrix is likely to be 1.74 nm which is 5.44 times higher than 0.321. Apratim et al [10] reported that the contribution by Δ ORO is significant in UST processed AZ91D/nano alumina (average particle size: 50 nm) composites up to 2 wt%. Nevertheless, Δ CTE has major contribution while Δ LT is negligible.…”

“…Besides, the higher surface to volume ratio and poor wettability of nanoparticles cause agglomeration which leads to deteriorated grain structure. A novel Ultrasonic Treatment (UST) in the composite melt is taken up for overcoming these issues [8][9][10]. UST eliminates the nanoparticle clusters of agglomeration and efficiently disperses them throughout the metal matrix by 'cavitation effect'.…”

Advanced Metal Matrix Nanocomposites

“…Khandelwal et al [32] assessed the mechanical behavior of AZ31/Al 2 O 3 magnesium alloy nanocomposites prepared using ultrasound-assisted stir casting (nano-sized alumina powder with the average size of 30 to 70 nm) with different wt% of alumina nanoparticles (0.5, 1.0, and 2.0 wt%). The melt was subjected to ultrasonic treatment (UST) under two different conditions, i.e., UST performed outside the furnace during air-cooling and nearly isothermal (Iso) UST within the furnace (see Figure 2).…”