No abstract

In the area of metal matrix composites, novel reinforcing options are currently being evaluated. Particles of amorphous alloys present an interesting possibility to reinforce soft metals. In the present work, the interaction between Fe66Cr10Nb5B19 metallic glass and aluminum during Spark Plasma Sintering (SPS) was studied for the first time. In order to trace the phase and microstructural changes upon sintering, mixtures containing 20 vol.% and 50 vol.% of metallic glass were subjected to SPS at 500-570 ºC. After SPS at 500 ºC, no reaction layer between the metallic glass particles and aluminum was observed. After SPS at 570 ºC, a reaction layer containing Fe2Al5 and FeAl3 formed around the Fe-based cores. The Vickers hardness of composites obtained from mixtures containing 20 vol. % Fe66Cr10Nb5B19 at 540 ºC was 75 HV and increased to 280 HV after sintering at 570 ºC due to the formation of thicker reaction layers at the interface.The hardness of the composite sintered from the mixture containing 20 vol. % Fe66Cr10Nb5B19 at 570 ºC was between the values predicted by Reuss and Voigt models.Comparison of results of SPS of the powder mixtures with those of SPS of a precompacted pellet and electric current-free annealing suggests that local heating at the interface caused by interfacial resistance may be an important factor influencing the reaction advancement at the interface and the formation of Al-containing intermetallics.

At present, metallic glasses are evaluated as alternative reinforcements for aluminum matrix composites. These composites are produced by powder metallurgy via consolidation of metallic glass-aluminum powder mixtures. In most studies, the goal has been to preserve the glassy state of the reinforcement during consolidation. However, it is also of interest to track the structure evolution of these composites when partial interaction between the matrix and the metallic glass is allowed during sintering of the mixtures. The present work was aimed to study the microstructure and mechanical properties of composites obtained by spark plasma sintering (SPS) of Al-20 vol.% Fe66Cr10Nb5B19 metallic glass mixtures and compare the materials, in which no significant interaction between the matrix and the Fe-based alloy occurred, with those featuring reaction product layers of different thicknesses. Composite materials were consolidated by SPS at 540 and 570 °C. The microstructure and mechanical properties of composites obtained by SPS and SPS followed by forging, composites with layers of interfacial reaction products of different thicknesses, and metallic glass-free sintered aluminum were comparatively analyzed to conclude on the influence of the microstructural features of the composites on their strength.