An Investigation on the Effect of Heat Treatment on the Compression Behavior of Aluminum Matrix Syntactic Foam Fabricated by Sandwich Infiltration Casting

Abstract

In this research, syntactic foams including Al-7075 matrix and 2-4 mm low-cost pumice particles were manufactured via a novel casting method called as sandwich infiltration. According to physical evaluations, thanks to extremely porous structure of pumice, density values of the fabricated foams varied between 1.42 and 1.61 g/cm 3. Porosity values were between 40.62% and 47.39%. Microstructural observations showed that there was a perfect infiltration between Al matrix and pumice particles because of correct process optimization (process pressure of 0.1 MPa, matrix melting temperature of 720°C and filler pre-temperature of 500°C). Furthermore, T6 treatment was applied to samples to comprehend effect of the aging on mechanical properties. The results indicated that there was an affirmative relation between the heat treatment and quasi-static compressive properties of the fabricated foams. The highest compressive strength, plateau stress and energy absorption values were measured as 64.4 MPa, 74.3 MPa and 34 MJ/m 3 for heat treated samples. It was also observed that although the highest energy efficiency of 0.89 was calculated for heat treated sample, there was no relation between the heat treatment and efficiency. As for failure modes, as-cast samples exhibited ductile barreling characteristic whereas T6 treated foams indicated brittle v-shape fracture.

Stir Casting Routes for Processing Metal Matrix Syntactic Foams: A Scoping Review

“…SFs produced by metallic matrices are known as metal matrix syntactic foams (MMSFs). MMSFs exhibit higher density than conventional metal foams (MFs) and demonstrate superior mechanical properties [9]. Based on the same concepts, a specific type of MMSF Processes 2022, 10, 478 2 of 24 can be found in the literature, referred to as composite metal foams (CMF).…”

“…Major target sectors for implementing MMSFs include the automotive, railway, aerospace, and construction industries, due to the critical parameters that limit for the ability of designing new components: ductility, energy absorption, and low density. In transport industries (by ground, air, and water), lightweight components may enhance fuel efficiency and thus reduce pollutant emission [9]. Moreover, the superior reduction of dynamic loading properties makes them suitable for military vehicles and mine blast protection [3,12].…”

“…Nonetheless, it also exhibits certain shortcomings according to the literature available to date, of which the following are worth mentioning: inhomogeneous filler distribution due to buoyancy effect, fragmentation of hollow fillers owing to mechanical mixing, lower volume fraction of the filler particles compared to the theoretically possible, difficulties for controlling the distribution of space holders and premature solidifying of the melt due to thermal shock between cold fillers during the mixing step. The premature solidifying phenomenon of the melt in contact with cold fillers can be addressed by preheating the fillers before the mixing step [6,9,13].…”

Influences of reinforcement size and artificial aging on the compression features of hybrid ceramic filled aluminum syntactic foams

“…If the previous papers are scrutinized, Taherishargh et al 22 found that 2.8-4 mm pumice-filled foams had a density range of 1.48-1.50 g/cm 3 . In another work, Bolat et al 21 produced 2-4 mm pumice-added AA7075 foams and the density levels exceeded 1.60 g/cm 3 . As for expanded glass, Bolat et al 15 applied the same technique offered in this paper and proclaimed that density intervals altered between 1.22-1.30 g/cm 3 and 1.41-1.50 g/cm 3 for 2-4 mm and 1-2 mm glass-filled samples, respectively.…”

“…Also, it should be noted that compared to other reinforcement ceramics, pumice has a big potential and was studied solely in a few MMSF projects. [21][22][23] Figure 1 illustrates macro-and micro-images of the reinforcement particles. Furthermore, it is also true to say that although pumice and expanded glass particles display low elongation and poor ductility owing to their low fracture toughness, these ceramic materials provide a noteworthy rigidity and porosity to the aluminum matrix.…”