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Zr–Co–Al alloys are widely used due to their good biocompatibility and high-pressure properties. In the present work, the Zr 54.5 Co 33.5 Al 12 alloy was prepared by rapid solidification. It has been found that the central region (b region) and the edge region (d region) have obvious changes in the microstructure, with the b region contains a large number of crystalline phases, and the d region can obviously observe the morphology of the amorphous state except a few dendrites. A certain amount of amorphous is contained in the d region as detected by XRD analysis. The fracture strength can undoubtedly reach up to 2031 MPa and the fracture strain is about 1.8 %. TEM analysis revealed the B2-to-B33 phase transition in the deformed alloy, and a significant number of nanotwins with a {111} <121> type of twin relationship were observed in the B33 ZrCo phase. Furthermore, the stacking fault energy (SFE) for varying applied stresses was calculated. From the calculation results, the negative SFE (about −41 mJ/m2) is beneficial to the B2-to-B33 phase transition, and it is known that twin thickness decreases with decreasing SFE. • The negative stacking fault energy is beneficial to the B2-to-B33 phase transition. • The twin thicknesses on B33 phase decrease with a reduction in stacking fault energy. • B2-to-B33 martensitic transformation can effectively improve the mechanical properties of Zr 54.5 Co 33.5 Al 12 alloy. [ABSTRACT FROM AUTHOR]

• Al-7075 was reinforced by different contents of Fe-based metallic glass particles. • The composites were prepared by spark plasma sintering and hot extrusion. • The composites possess higher mechanical properties than unreinforced Al-7075. • The composites are reinforced mainly by thermal mismatch and grain refinement. Metallic glass (MG) reinforced aluminum matrix composites (AMCs) have attracted the interest of many researchers in the past few years. In this study, Fe 50 Cr 25 Mo 9 B 13 C 3 metallic glass (FMG) particles reinforced 7075 aluminum matrix (Al-7075) composites were prepared by spark plasma sintering (SPS) technique. The microstructure of the composites showed good interface bonding between the FMG particles and the matrix. The micro-hardness of the composite with 30 vol% FMG particles reached 160.63 HV, which was increased by 30% compared with that of Al-7075 (119.3 HV). The ultimate compression strength (UCS) of the composite was also improved significantly from 596 MPa for Al-7075 matrix to 749 MPa for the composite reinforced with 30 vol% FMG particles, and the compression strain of the composite reached 22%. These results indicate that the mechanical properties of the composites can be enhanced by adding high volume fraction FMG particles. The enhancement of the strength is resulted from multiple strengthening mechanisms, and the main contributions come from the thermal mismatch and grain refinement. [ABSTRACT FROM AUTHOR]

[Display omitted] • In-situ growing carbon nanotubes (CNTs) on the surface of Ti particles prepared a novel CNTs@Ti hybrid reinforcement. • CNTs with good structural integrity were evenly dispersed into the Al matrix owing to the carrying effect of Ti particles. • The precipitation of nano-scaled TiC, Al 4 C 3 and TiAl 3 enhanced the interface bonding of CNT/Al. • The high strength of composite can attribute to the multi-phase coupling synergistic strengthening effect. The strengthening effect of carbon nanotubes (CNTs) in Al matrix composites (AMCs) is significantly weakened by CNTs agglomeration and unsubstantial interfacial bonding with the Al matrix. In this study, CNTs were grown on the surface of Ti particles by chemical vapor deposition to obtain CNTs@Ti hybrid reinforcement, followed by powder metallurgy to prepare CNTs@Ti/Al composites. Evenly dispersed CNTs with good structural integrity were successfully obtained using the carrying effect of the micron-sized Ti particles. Meanwhile, TiC, Al 4 C 3 , and TiAl 3 were generated at the CNT/Al interface, which strengthened the bearing capacity of the inner-wall of the CNTs, improved the wettability of the CNT/Al interface, and enhanced the strain-hardening ability of the Al matrix. The deficiencies in the CNTs/Al composites are compensated by this kind of materials design, and the two types of reinforcements have a synergistic strengthening effect, which greatly improves the comprehensive mechanical properties of AMCs. An excellent interface structure is formed by controlling the interface reaction such that the dispersion, grain boundary, dislocation, and load transfer strengthening mechanisms are fully realized. [ABSTRACT FROM AUTHOR]

Aluminum matrix composites (AMCs) reinforced with novel carbon nanotube (CNT)-Fe-based metallic glass (FMG) synergistic reinforcements were successfully prepared by powder metallurgy. The CNT-FMG reinforcements were obtained by growing CNTs on the surface of FMG particles using chemical vapor deposition (CVD). By controlling the catalytic temperature, the grown CNTs exhibited good morphology, a high degree of graphitization, and thermal oxidation stability. CNTs were homogeneously dispersed in the Al matrix through the carrying action of FMG particles. The CNT-FMG synergistic reinforcements significantly improved the mechanical properties of the composite, and formed a tight interfacial bonding with the Al matrix. The CNT-FMG reinforcements had a remarkable synergistic strengthening effect on the composite. • CNTs were grown on the surface of FMG particles by chemical vapor deposition. • CNT-FMG synergistic reinforced Al matrix composites were prepared. • CNTs were homogeneously dispersed in Al matrix through the carrying of FMG. • CNT-FMG contributed remarkable synergistic strengthening effect to the composite. [ABSTRACT FROM AUTHOR]

Unlike crystalline alloys, disordered amorphous alloys lack long-range order. Even today, the creep mechanisms for amorphous alloys are far from being fully understood. In this work, an Fe–Cr–Mo–B–C (Cr: 25–27 wt%, Mo: 16–18 wt%, B: 2.0–2.2 wt%, and C: 2.0–2.5 wt%) amorphous coating was fabricated on the surface of a 304 stainless steel via atmospheric plasma spraying with a NiAl bonding layer. In this study, the effects of peak load and loading rate on the creep deformation behavior of the Fe-based amorphous coatings were investigated. The results demonstrated that a macroscopic viscous flow behavior was obtained at low peak loads, which led to a larger creep strain rate sensitivity m. At high loading rates, the accumulation of free volume led to an increase in the shear deformation zone and a more uniform plastic rheology. It indicated that at higher loading rates, the amorphous coating had higher m values under steady-state creep. • An Fe–Cr–Mo–B–C amorphous coating was successfully prepared via APS. • Lower peak loads result in larger creep strain rate sensitivity. • Higher loading rates result in larger creep strain rate sensitivity. • Free volume accumulation and STZ rearrangement affect plastic deformation. [ABSTRACT FROM AUTHOR]

Fe–Cr–Mo–B–C amorphous powders are usually used in thermal spraying, spark plasma sintering or 3D printing to prepare coatings or large-sized bulk amorphous alloys. However, their non-isothermal crystallization kinetics is far from being investigated in detail because of their relatively complicated crystallization behavior. In this work, the phase evolution, crystallization kinetics and crystallization mechanism of Fe–Cr–Mo–B–C (Cr: 25–27 wt%, Mo: 16–18 wt%, B: 2–2.2 wt%, C: 2–2.5 wt%) amorphous powder during non-isothermal crystallization are analyzed by X-ray diffraction, scanning electron microscope and differential scanning calorimetry together with Ozawa method and local Avrami exponent. The peak temperature of the first precipitated phase is less sensitive to the heating rate. In the non-isothermal crystallization process upon constant-rate heating to elevated temperatures the phase sequence is: α -Fe, M 23 (C, B) 6 , M 7 C 3 and FeMo 2 B 2 (M = Fe, Cr, Mo). The apparent activation energy of crystallization of the amorphous powders obtained using Kissinger's method is between 385 and 557 kJ/mol, which is higher than that of most iron-based amorphous alloys reported so far, indicating a relatively high stability against crystallization. a -Fe and FeMo 2 B 2 have a similar transformation mechanism: the early phase transition is completed by diffusion controlled growth with an increasing nucleation rate; as the crystallized volume fraction increases, the nucleation rate decreases, and nucleation does not occur even in the later stage of crystallization. The crystallization mechanism of M 23 (C, B) 6 and M 7 C 3 is similar: when the crystallized volume fraction α is higher than 0.1, only crystal growth occurs. This might be due to the fact that the large number of interfaces formed between the early precipitated phase and the amorphous matrix promote nucleation, rendering nucleation complete at the stage when the crystallized volume fraction α is less than 0.1. Therefore, the first and fourth crystallization events are diffusion controlled, the second and third crystallization events are primarily governed by grain growth. • A Fe–Cr–Mo–B–C amorphous powder was successfully prepared by atomization. • The amorphous alloy has a high resistance to crystallization. • The crystallization process is controlled by diffusion. [ABSTRACT FROM AUTHOR]