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Metallic-glass-reinforced metal matrix composites are a novel class of composite materials, in which particles of alloys with an amorphous structure play the role of reinforcement. During the fabrication of these composites, a crystalline metal is in contact with a multicomponent alloy of an amorphous structure. In the present work, the morphological features of the reaction products formed upon the interaction of Fe66Cr10Nb5B19 metallic glass particles with aluminum were studied. The composites were processed via spark plasma sintering (SPS), hot pressing or a combination of SPS and furnace annealing. The reaction products in composites with different concentrations of the metallic glass and different transformation degrees were examined. The products of the interaction of the Fe66Cr10Nb5B19 metallic glass with Al were observed as dense layers covering the residual alloy cores, needles of FeAl3 protruding from the dense shells as well as needles and platelets of FeAl3 distributed in the residual Al matrix. The possible role of the liquid phase in the structure formation of the reaction products is discussed. The formation of needle- and platelet-shaped particles presumably occurred via crystallization from the Al-Fe-based melt, which formed locally due to the occurrence of the exothermic reactions between aluminum and iron. At the same time, aluminum atoms diffused into the solid Fe-based alloy particles, forming an intermetallic layer, which could grow until the alloy was fully transformed. When aluminum melted throughout the volume of the composite during heating of the sample above 660 °C, a similar microstructure developed. In both Al–Fe66Cr10Nb5B19 and Al–Fe systems, upon the reactive transformation, pores persistently formed in locations occupied by aluminum owing to the occurrence of the Kirkendall effect. [ABSTRACT FROM AUTHOR]

When metals are modified by second-phase particles or fibers, metal matrix composites (MMCs) are formed. In general, for a given metallic matrix, reinforcements differing in their chemical nature and particle size/morphology can be suitable while providing different levels of strengthening. This article focuses on MMCs reinforced with metallic glasses and amorphous alloys, which are considered as alternatives to ceramic reinforcements. Early works on metallic glass (amorphous alloy)-reinforced MMCs were conducted in 1982–2005. In the following years, a large number of composites have been obtained and tested. Metallic glass (amorphous alloy)-reinforced MMCs have been obtained with matrices of Al and its alloys, Mg and its alloys, Ti alloys, W, Cu and its alloys, Ni, and Fe. Research has been extended to new compositions, new design approaches and fabrication methods, the chemical interaction of the metallic glass with the metal matrix, the influence of the reaction products on the properties of the composites, strengthening mechanisms, and the functional properties of the composites. These aspects are covered in the present review. Problems to be tackled in future research on metallic glass (amorphous alloy)-reinforced MMCs are also identified. [ABSTRACT FROM AUTHOR]

Heating of conductive materials by electric current is used in many technological processes. Application of electric pulses to metallic glasses induces their fast crystallization, which is an interesting and complex phenomenon. In this work, crystallization of the FeB amorphous alloy induced by pulses of electric current produced has been studied using X-ray diffraction and transmission electron microscopy. Ribbons of the alloy were directly subjected to single pulses of electric current 250 µs long formed by a capacitor discharge. As the value of $$\smallint I^{2} {\text{d}}t$$ was increased from 0.33 to 2.00 A s, different crystallization stages could be observed. The crystallization began through the formation of the nuclei of α-Fe. At high values of $$\smallint I^{2} {\text{d}}t$$ , α-Fe and tetragonal and orthorhombic FeB and FeB were detected in the crystallized ribbons with crystallites of about 50 nm. Thermal annealing of the ribbons at 600 °C for 2 min resulted in the formation of α-Fe and tetragonal FeB. It was concluded that pulses of electric current produced by a capacitor discharge induced transformation of the FeB amorphous phase into metastable crystalline products. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Ti 25 Cu 75 alloy was as a source of Ti and Cu to synthesize TiC-Cu nanocomposites. • During milling, the alloy experienced crystallization and decomposition. • In sintered composites, there were Cu regions 0.5–1 µm in size free from TiC. • Ti-Cu intermetallics transformed into non-agglomerated TiC 10–20 nm in size. • Hardness of nanocomposites exceeded that of conventional TiC-Cu composites. Abstract In this work, Ti 25 Cu 75 melt-spun partially amorphous alloy was used as a source of Ti and Cu to synthesize in-situ TiC-Cu nanocomposites. The reaction between the alloy and carbon started during ball milling and continued during Spark Plasma Sintering. At the same time, during ball milling, the alloy experienced phase transformations: crystallization of the amorphous phase was followed by decomposition of TiCu 3. Copper crystallites formed during the alloy transformations were the reason for the presence of copper regions 0.5–1 µm in size free from TiC nanoparticles in the sintered composites. The Ti-Cu intermetallics transformed into non-agglomerated TiC 10–20 nm in size distributed in the copper matrix. The hardness of the synthesized TiC-Cu nanocomposites exceeded that of composites obtained by conventional sintering of ball-milled Ti-C-Cu powders. [ABSTRACT FROM AUTHOR]

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 Fe 66 Cr 10 Nb 5 B 19 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 °C. After SPS at 500 °C, no reaction layer between the metallic glass particles and aluminum was observed. After SPS at 570 °C, a reaction layer containing Fe 2 Al 5 and FeAl 3 formed around the Fe-based cores. The Vickers hardness of composites obtained from mixtures containing 20 vol% Fe 66 Cr 10 Nb 5 B 19 at 540 °C was 75 HV and increased to 280 HV after sintering at 570 °C due to the formation of thicker reaction layers at the interface. The hardness of the composite sintered from the mixture containing 20 vol% Fe 66 Cr 10 Nb 5 B 19 at 570 °C 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 pre-compacted 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. • Interaction between Fe 66 Cr 10 Nb 5 B 19 metallic glass and Al during SPS was studied. • After SPS at 500 °C, no reaction layer between the alloy and Al was observed. • After SPS at 570 °C, a layer of Fe 2 Al 5 and FeAl 3 formed around the alloy cores. • Reaction advancement is influenced by local heating at the interface during SPS. • Hardness of composites is compared with values given by Voigt and Reuss models. [ABSTRACT FROM AUTHOR]