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Abstract New Ti-based bulk metallic glasses (BMGs) of Ti 32.8+X Zr 30.2−X Ni 5.3 Cu 9 Be 22.7 (3 ≤ |X| ≤ 15, at.%) with large size were prepared. The results reveal that the forming of primary icosahedral quasicrystal phase (I-phase) and the enthalpy of the primary crystallization (Δ H 1) were closely related to the glass forming abilities (GFAs). The crystallization product of the metallic glass alloys at primary crystallization state is a metastable I-phase. It is demonstrated that apparent activation energy for crystallization obtained by fitting the Kissinger equation at T x temperature increases with the increase of Ti concentration, while GFAs deteriorate. The Δ H 1 of metallic glasses declines with the increase of Ti concentration. The Ti 32.8+X Zr 30.2−X Ni 5.3 Cu 9 Be 22.7 possess high similar compressive fracture strength of about 1800 MPa, which is one of the best options as structural materials on account of high specific strength and low cost. [ABSTRACT FROM AUTHOR]

Highlights • A new Ti-based BMGC with the composition of Ti 57.3 Zr 19.6 Cu 4.7 Ni 2.8 Be 12 Nb 3.6 was developed. • The composite shows large homogeneous ductility and significant work-hardening capacity. • The toughening mechanism is a combined effect of stress-induced martensitic transformation and mechanical twinning. Abstract A new Ti-based BMGC with excellent tensile plasticity and significant work-hardening capacity was successfully developed. The microstructure, mechanical behaviors and toughening mechanisms were investigated in details by SEM, XRD, TEM and Nano-indentation. It is found that the stress-induced martensitic transformation from β to α″ phase and the mechanical twinning in the α″ phase combined to account for these mechanical behaviors. The current work offers a new perspective for developing in situ dendrite reinforced BMGCs with improved homogeneous ductility and significant work-hardening capacity. [ABSTRACT FROM AUTHOR]

Up to now, few work has concerned about the composition design strategy in the field of in-situ dendrite bulk metallic glass composites (BMGCs) for the difficulty to mediate single element in the multi-component system. In this work, an innovative composition design strategy was proposed, and a novel series of in-situ β dendrite reinforced Ti-based BMGCs were prepared. It was found that the real composition of the in-situ formed dendrites and amorphous phase is well consistent with the designed one. Accordingly, the dendrite composition is tailored monotonically and precisely, while the composition and volume fraction keep similar for the amorphous matrix in the composites. The microstructure of the dendrites and the mechanical properties and mechanisms of the overall composites are essentially controlled by the dendrite composition. According to the corresponding deformation mechanisms which transform from stress-induced martensitic transformation and mechanical twinning to dislocation slip, these alloys can be classified into two groups: the stress-induced martensitic transformation type and the none-phase transformation type. The composition design strategy proposed in this work and the correlation between the dendrite composition and the mechanical mechanisms may provide useful guidance for the development of in-situ β dendrite reinforced BMGCs with optimized mechanical properties. [ABSTRACT FROM AUTHOR]

A novel series of in - situ dendrite Ti-based bulk metallic glass composites (BMGCs) were obtained. The Mo content of the dendrites monotonically increases from nil to 10.5 at% while the dendrite volume fraction and the composition of the amorphous matrix remain nearly invariant. It was found that the mechanical behaviors varied tremendously simply by changing the Mo content. Thus, the correlation between the composition and the mechanical behaviors under tension has been determined for in - situ dendrite Ti-based BMGCs for the first time. [ABSTRACT FROM AUTHOR]

Lightweight materials with good combinations of properties, such as high strength, ductility and damage tolerance, are highly desirable in engineering applications; nevertheless, it remains a challenge to "defeat" the generally exclusive relationships between different properties for structural materials. One viable means is to construct complicated architectures in materials. Here, we employ a lightweight Ti-based metallic glass (MG) and pure Ti as constituents and assemble them into a hierarchically-structured multiphase composite with tailored heterogeneity. The Ti-rich multiphase composite exhibits a relatively low density of 4.95 g ∙ c m − 3 owing to its high Ti content and a high strength of ∼1408 MPa derived primarily from the MG phase. The hierarchical architecture with tailored heterogeneity promotes the formation of abundant shear bands and microcracks in MG, yet inhibits their extension to avoid catastrophic fracture, thereby endowing the Ti-rich multiphase composite with a remarkable tensile ductility of ∼7.1% which is nearly two times that of the MG composite having similar phase constitution but a uniform structure. Moreover, this architecture causes crack-tip blunting by promoting plastic deformation, together with crack bifurcation and microcracking ahead of the crack tip, which bestows a high (notched) fracture toughness of ∼109 M P a ∙ m 1 / 2 which is around three times that of its counterpart. This study is intended to give insight for the architectural design of new materials by offering a viable means for their architectural construction to achieve good combinations of properties. [ABSTRACT FROM AUTHOR]

A new method was proposed to pinpoint the compositions with good glass forming ability (GFA) by combining atomic clusters and mixing entropy. The clusters were confirmed by analyzing competing crystalline phases. The method was applied to the Zr–Al–Ni–Cu–Ag alloy system. A series of glass formers with diameter up to 20 mm were quickly detected in this system. The good glass formers were located only after trying 5 compositions around the calculated composition. The method was also effective in other multi-component systems. This method might provide a new way to understand glass formation and to quickly pinpoint compositions with high GFA. [ABSTRACT FROM AUTHOR]