Abstract
Hybrid Ni/Al foams were fabricated by depositing electroless Ni–P (EN) coatings on open-cell Al foam substrate to obtain enhanced mechanical properties. The microstructure, chemical components and phases of the hybrid foams were observed and analyzed by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD), respectively. The mechanical properties of the foams were studied by compressive tests at different temperatures. The experiment results show that the coating is mainly composed of Ni and P elements. There was neither defect at the interface nor crack in the coatings, indicating that the EN coatings had fine adhesion to the Al substrate. The compressive strengths and energy absorption capacities of the as-received foam and hybrid foams decrease with the increasing testing temperatures, but the hybrid foams exhibit a lower decrement rate than the as-received foam. This might be attributed to the different failure mechanisms at different testing temperatures, which is conformed by fractography observation.
Highlights
Aluminum foam is a kind of material with a combination of some attractive physical and functional properties, such as low density, high energy absorption capacity, and excellent damping property [1,2].The compressive property is one of the important properties of metal foam [2]
The scanning electron microscopy (SEM) results indicated a plasma electrolytic oxidation (PEO) ceramic coating that mainly consists of oxides exhibiting a two-layer structure: the inner layer is characterized by fine-scale pores, while the outer layer contains much coarser pores [14]
The surface topographies of the as-received foam and electroless Ni–P (EN) coatings are shown in Figures 2 and 3, respectively
Summary
Aluminum foam is a kind of material with a combination of some attractive physical and functional properties, such as low density, high energy absorption capacity, and excellent damping property [1,2]. It is generally accepted that the compressive property relies on many factors, such as the relative density and porosity [3,4], the property of cell wall material [5,6], cell wall microstructure [7,8,9], the testing temperature [10,11,12] and surface coating on the foam [13,14,15,16,17,18,19]. Hybrid metal foams can be created by reinforcing open-cell Al foam with metal base coatings (Cu and Ni) using electrodeposition Excessive annealing results in a number of intermetallic compounds at the Al/Cu interface, which reduces the performance of the hybrid foams [19] These experiments mentioned above mainly described the mechanical properties of the hybrid foams at room temperature, but limited experimental data at elevated temperature were available. The failure mechanisms of the Ni/Al hybrid foams at different testing temperatures were investigated by means of SEM observation and energy-dispersive X-ray spectroscopy (EDS) analysis
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