A metallic glass syntactic foam with enhanced energy absorption performance

Abstract

By using the high-pressure melt infiltration technique, a syntactic foam is fabricated with bulk metallic glass and alumina cenospheres. Compared to pure metallic glass foams, the new foam possesses a greatly enhanced energy absorbing capacity of 113.6 MJ m −3 due to the combination of high strength, stability and ductility. It is shown that the high strength of the foam primarily results from alumina cenospheres, which enhance its stability and induce a stable stress platform. Both the collapse of struts and multiple shear bands in metallic glass matrix accommodate large deformation.

Molten Metal Infiltration Methods to Process Metal Matrix Syntactic Foams

“…Metal alloys commonly employed by this technique do not have high melting points, according to some studies [17,18,22,72]. Notwithstanding this, recent enhancements of liquid metal infiltration technology has enabled metal alloys with both low to medium (such as those based on tin [33,73], zinc [2,5], magnesium [57] and aluminum [39,56]) and high melting point (such as those based on iron [74,75], titanium [5] and bulk metallic glass or amorphous metals [55,76,77]) to be used to produce SF by this technique.…”

“…An ingot of metal alloy is placed into the container as shown below in Figure 5. The assembly is then placed into a chamber (Figure 5b) and exposed to vacuum atmosphere [76]. Due to vacuum environment, the matrix melting is achieved with induction coils.…”

“…After that, the vessel is pressurized while a pressure difference is created above and under the sealing of liquid cork which induces the metal infiltration across the insulator mesh into the evacuated preform [39,88]. Finally, the assembly is cooled in different manners, as reported Lin et al [76] by being submerged into a mixture of NaCl solution and ice cubes to quickly cool it down or through a controlled cooling rate, resulting in a minimal unintentional porosity according to Balch's study [99].…”

“…These results suggest that this approach can be scaled up. H. Lin et al [76] and A.H. Brothers, D.C. Dunand [77] reported that this method can also be successfully scaled up to manufacture amorphous MMSF with a relative density of 50%. In addition, in those cases in which pressure infiltration is significantly higher than the threshold pressure of the bed of particles, the un-infiltrated voids can be neglected.…”

“…The main manufacture parameters which govern this route are processing temperature [60], infiltration pressure and time of infiltration, which defines length of infiltration [58,88]. Many researcher groups have been working on this method and they reported the following key points: Sant Maria et al [69], Szlancsik et al [56], Lin et al [76] successfully applied a great range of infiltration pressures, ranging from 0.04 to 6 MPa. The system selected by Palmer et al [60] may aid the scale up of the process and extend to highly complex geometries.…”