Bulk amorphous Al85Fe15 alloy and Al85Fe15-B composites with amorphous or nanocrystalline-matrix produced by consolidation of mechanically alloyed powders

An Al80Fe14B6 powder mixture was subjected to mechanical alloying. Presence of an amorphous structure in the milling product was revealed by XRD investigations. The calorimetric study showed that the amorphous phase crystallised above 370 °C. The milled Al80Fe14B6 powder was consolidated under a pressure of 7.7 GPa in different conditions: at 350 °C and at 1000 °C. Besides, the mechanically alloyed amorphous Al85Fe15 powder was consolidated at 360 °C. The amorphous structure was retained after consolidation applied at 350 °C and 360 °C. Compaction at 1000 °C caused crystallisation of the amorphous phase and appearance of metastable nanocrystalline phases. Structural investigations revealed that both bulk Al80Fe14B6 samples are composites with boron particles embedded in amorphous or nanocrystalline matrix. The hardness of the nanocrystalline-matrix composite and of the amorphous-matrix one is equal to 707 HV1 and 641 HV1 respectively, whereas that of bulk amorphous Al85Fe15 alloy is 504 HV1. The specific yield strength of amorphous-matrix and nanocrystalline-matrix composites, estimated using the Tabor relationship, is 625 and 650 kNm/kg respectively, while that of amorphous Al85Fe15 alloy is 492 kNm/kg. We also suppose that application of high pressure affected crystallisation of amorphous phase, influencing the phase composition of the products of this process.

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► We produced amorphous/nanocrystalline Al85Fe15 matrix composites reinforced with B.
► The hardness of amorphous-matrix composite is 6.29 GPa
► The hardness of nanocrystalline-matrix composite is 6.94 GPa
► The specific yield strength of amorphous-matrix composite is 625 kNm/kg.
► The specific yield strength of nanocrystalline-matrix composite is 650 kNm/kg.