Uzyskano piany aluminiowe ze stopu AISi12Mg1-1%TiH2 wykonane metodą metalurgii proszków. Otrzymane w różnych temperaturach piany poddano pomiarom gęstości, analizie strukturalnej i jednoosiowej próbie ściskania. Przeprowadzone badania wykazały, że wraz z malejącą gęstością (będącą wynikiem wzrostu temperatury spieniania) maleją liczba porów na jednostkę powierzchni NA i powierzchnia względna w objętości jednostkowej SV, a objętość porów VV rośnie. Nieco inną charakterystykę przedstawia piana o gęstości względnej 0,2, która ma najbardziej jednorodną strukturę pod względem wielkości i kształtu porów. Piana ta charakteryzuje się również najwyższą względną wytrzymałością na ściskanie (bc/d = 37 MPa; bc - wytrzymałość na ściskanie, d = plps - gęstość względna). Tylko piany o gęstości względnej mniejszej od 0,3 wykazują charakterystyczne dla pian tzw. plateau.
The precursor material, in a form of a rectangular rod 20x5 mm, was prepared by extrusion of a mixture of powders: AISi12Mg1-1%TiH2. The samples of the precursor rod (20x20x5 mm) were foamed at temperatures in the range of 600:800°C, in times 3:30 min. The density of the foams was measured after removing their surface metallic skin, which for small samples had a substantial influence on the mechanical properties. The foam structure was studied using computer image analysis method. The foams, which were foamed at various temperatures, exhibited different structure (Fig. 1). Even without special analysis one can see that the foam, which had relative density 0.2, exhibited most regular and homogeneous pore structure. In Figure 2a the parameters such as relative number of pore sections Na, relative pore area within a unit volume Sv and relative pore volume Vv are plotted versus relative density. With decreasing density the volume parameter Vv increased and the parameters SV and na decreased. However, when the pores in the walls were neglected the parameters, na and Sv showed a maximum for the foam, which had relative density 0.2. The dependence for Vv did not change (Fig. 2b). The calculated values of average pore size and shape of pores were substantially influenced by the small pores in the walls. The best structural homogeneity, represented by the narrow distribution of equivalent diameter - d2, was found again for the foam having relative density 0.2 (fig. 4). The foams processed at temperatures lower and higher than 700°C exhibited much broader distribution of the pore size. The lowest density foams showed large pores with the equivalent diameter up to 7:8 mm. The appearance of very large pores for the foams, which had been processed at high temperature, was supposed to be caused by a fast growth of small pores and their interconnections. Another significant parameter in structural analysis of metallic foams is the pore shape. For the characterisation of the pore shape such parameters as the elongation and convexity were calculated. The most circular pore structure showed the foam with relative density 0.2. The foams were subjected to the compressive tests. The deformation was parallel to the foaming direction. The specimens having densities between 0.1 and 0.26 exhibited curves typical of foam materials with characteristic, extended plateau, ranging up to 60% strain (Fig. 5). The sample with density 0.49 did not show plateau. The highest relative compressive strength (37 MPa) attained the foam having relative density 0.2. The best mechanical properties exhibited foam, which had the maximum value of stereological parameters Sy and NA and the most regular and homogeneous pore structure. The experiments proved that the mechanical properties of aluminium foam depend not only on their density, but also on the pore structure.