Papers by Keyword: Melt Foaming Method

Abstract: Closed-cell aluminum foam with different percentages of Cu was prepared by melt foaming method.The effect of Cu element on the quasi-static compressive properties of aluminum foam was investigated, both under as-cast and heat-treated conditions. The results showed that Cu element distributed in cell wall matrix mainly in the forms of Al-Cu solid solutions and AlCu3, Al_6.1Cu_1.2Ti_2.7 intermetallics. Meanwhile, Cu-containing foams possessed much higher compressive strength than the commercially pure aluminum foams. Additionally, proper heat treatment could further improve the yield strength of Cu-containing foams and the effect of aging treatment was more obvious than the homogenizing heat treatment under the present conditions and the reasons were discussed.

Abstract: Al foams whose matrix contains dispersed AlN particles (Al/AlN composite foams) were prepared by a melt foaming method, and the effect of foaming temperature on the pore morphology of the prepared foams was investigated. First, Al/AlN composites were prepared by non-compressive infiltration of Al powder compacts with molten Al alloy in nitrogen atmosphere. Next, the prepared composites were melted by induction heating and foamed at various temperatures using TiH2 powders as blowing agents. The porosity of prepared Al/AlN composite foams slightly decreases with increasing foaming temperature, and the pore morphology of the foam becomes homogeneous simultaneously. When the foaming temperature is 1123 K, homogeneous pores are formed in all over the ingot. This pore homogeneity is probably achieved by the stabilization of the foaming behavior due to the formation of Al3Ti particles in the melt and dispersion of AlN particles.

Abstract: Aluminum alloy foams, new materials belonging to a special class of porous materials, have been prepared using melt foaming method. Silicon was chosen alloying element due to its low density, high strength, effective casting and reduced shrinkage. Melt foaming method is cost-effective method to fabricate metal foam. Usually, TiH2 is applied to blowing agent, but its cost is high. CaCO3 is one of candidates to substitute TiH2 in the economic view-point. For the comparison of formability, Mg alloy foams were prepared by TiH2 and CaCO3. However, the decomposition temperature of CaCO3 is higher than that of TiH2. This paper will be discussed on the possible usage of CaCO3 in the Al melt.

Abstract: Al-Mg alloy foams were synthesized via conventional melt foaming method. Ca and TiH2 were introduced into molten Al-Mg alloys with different magnesium contents. The macrostructures of resultant alloy foams were analyzed and correlated with compressive properties estimated by compression test. It is shown that the pore structures observed in alloy foams degraded with increasing Mg contents. This tendency was shown to be consistent with compressive characteristics of corresponding alloy foams. In detail, plateau strength was high for Al-1wt%Mg alloy foams, exhibiting a gradual decrease in plateau strength with increasing magnesium content.

Abstract: Al-Mg alloy foams containing different Mg contents were synthesized via a conventional melt foaming method. The surface structures of pores formed in resultant foamed alloys was characterized by scanning electron microscopy and x-ray diffractometer. It was found that the pore structures were deteriorated with increasing Mg contents, while the percent porosities did not vary with increasing Mg contents, about 90% and 3~5 mm in pore size. The detailed microstructural examination conducted on increasing Mg containing alloy foams revealed presence of various oxide particles on the surface of individual cells, including MgAl2O4 particles in a form of fine spinel; its small amount for Al-1wt%Mg alloy foam but relative high amount of Al-4wt%Mg one. This suggested the negative effect of MgAl2O4 on the stable pore and thus cell structures in corresponding alloy foams. The possible mechanism associated with MgAl2O4 formation was discussed in the present study.