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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]

[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]