Closed-cell A356 aluminum alloy foams refined and modified were successfully fabricated by using barite calcium carbonate as thickening foaming agents, respectively. A melt treatment consisting of adding master alloys Al-5Ti-1B Al-10Sr for refining the dendritic microstructure modifying primary eutectic silicon, respectively, included in process. The mechanical properties manufactured analyzed ...

Abstract In this study, a kind of structural gradient metal hollow spheres composites (SG-MHSCs) were fabricated using two kinds 316L stainless steel with different diameters and A356 aluminum through the casting method. Then density SG-MHSCs was measured by direct measurement; microstructure characterized Scanning Electron Microscope. Meanwhile, acoustic performance MHSCs tested impedance tube...

The objective of the present work is to study the casting characteristics of various A1-Li alloys, which include fluidity and strengths of the alloys and their interaction with cast molds. Materials investigated are Al-Li-Mg and Al-Li-Cu-Mg alloys with Li content of 2.5 wt%. The results show that sand molds with resin binders are good for A1-Li casting. Ceramic coatings can further reduce the m...

Acoustic emission methods are used to investigate the nature and evolution of microfracture damage during uniaxial compression of ductile amorphous and brittle crystalline metal foams made from a commercial Zr-based bulk metallic glass, and to compare this behavior against that of aluminum-based foam of similar structure. For the amorphous foam, acoustic activity reveals evolution of the damage...

In this paper, we present our recent experimental results on buoyancy-induced convection in aluminum metal foams of different pore densities [corresponding to 5, 10, 20, and 40 pores per in. (PPI)] and porosities (0.89–0.96). The results show that compared to a heated surface, the heat transfer coefficients in these heat sinks are five to six times higher. However, when compared to commercially...

A comprehensive methodology that takes into account alloy solidification, shrinkage-driven interdendritic fluid flow, hydrogen precipitation, and porosity evolution has been developed for the prediction of microporosity fraction in aluminum A356 alloy castings. The mathematical models presented are implemented in a computational framework consistent with those of commercial casting codes, allow...

Much work has been done, in recent years, to characterize the factors that cause porosity in aluminum castings, and to analyze the impact of porosity or microstructural parameters on fatigue life. What has yet to be done is systematically separate out the effects of dendrite arm spacing and largest pore size from each other, and from the underlying chemical and process parameters that influence...