In the present study, closed-cell aluminum foams with different percentages of erbium (Er) element were successfully prepared. The distribution and existence form of erbium (Er) element and its effect on the compressive properties of the foams were investigated. Results show that Er uniformly distributes in the cell walls in the forms of Al3Er intermetallic compound and Al-Er solid solutions. Compared with commercially pure aluminum foam, Er-containing foams possess higher micro-hardness, compressive strength and energy absorption capacity due to solid solution strengthening and second phase strengthening effects. Additionally, the amount of Er element should be controlled in the range of 0.10wt.%–0.50wt.% in order to obtain a good combination of compressive strength and energy absorption properties

•CMs can homogeneously distribute in AZ31 composite foams.•Porosity of the foams increased first and then decreased with the increase of CMs.•Pore size of the foams decreased with CMs contents increasing.•Proper contents of CMs changed the compression fracture mode of the foams.Closed-cell AZ31 magnesium alloy foams with different percentages of hollow ceramic microspheres (CMs) are synthesized using modified melt foaming method. The distribution of CMs is investigated and also the effect of CMs on the foaming behaviors (specifically for porosity and pore size) and quasi-static compressive behaviors of Mg-based composite foams are characterized. The results show that CMs distribute in cell walls homogeneously and most of them are penetrated by magnesium alloy melt. In addition, the mean pore size declines with the increase of CMs percentage. Moreover, the overall porosity of the foams increases first and then decreases with the increase of CMs content, and the variation tendency is more obvious when the foaming temperature is lower (namely 680 °C). Besides, proper percentage of CMs changes the compression fracture mode of the foams from brittleness to ductility. OM/SEM/EDS/XRD detections and finite element analysis are applied to explain the reasons.Download full-size image

•Closed-cell Al foam with different content of microspheres was prepared.•The effects of microspheres on compressive properties of Al foams were studied.•The optimal content of microspheres has been obtained.In this paper, closed-cell aluminum foams with different kinds and contents of ceramic microspheres are obtained using melt-foaming method. The distribution and the effects of the ceramic microspheres on the mechanical properties of aluminum foams are investigated. The results show that both kinds of ceramic microspheres distribute in the foams uniformly with part in the cell wall matrix, some in adhere to the cell wall surface and part embed in the cell wall with portion surface exposed to the pores. Ceramic microspheres have an important effect on the yield strength, mean plateau stress, densification strain and energy absorption capacities of aluminum foams. Meanwhile, the content of ceramic microsphere in aluminum foams should be controlled in order to obtain good combination of compressive strength and energy absorption capacity. The reasons are discussed.

•A novel thickening agent for magnesium composite foam was obtained.•Evolution of bubble nucleation particles was discussed.•Foaming process of MCF with CM and grow up of bubbles were described.A new thickening agent (hollow ceramic microsphere, CM) together with a novel bubble nucleation particle (Mg2Si) for magnesium composite foam (MCF) was obtained. Initial morphology and evolution process of Mg2Si during preparation process were described. Meanwhile, initial morphology of Mg2Si which is favorable for absorption of initial tiny bubbles was confirmed. Transition process of Mg2Si phase and the coalescence behavior of bubbles along with the foaming process were analyzed based on the experimental results. According to the results obtained from this work, MCF (using CM as thickening agent) with homogeneous pore structures, superior mechanical properties and excellent corrosion resistance performance could be foreseeable.