Ti-based Metallic Glass Matrix Composites Research Articles

Development and Fabrication of Biocompatible Ti-Based Bulk Metallic Glass Matrix Composites for Additive Manufacturing.

Ti-based metallic glasses have a high potential for implant applications. The feasibility of a new biocompatible Ti-based bulk metallic glass composite for selective laser melting (SLM) had been examined. Therefore, it is necessary to design a high-glass-forming-ability Ti-based metallic glass (∆Tx = 81 K, γ = 0.427, γm = 0.763), to fabricate a partial glass-formable spherical powder (the volume fraction of the amorphous phase in the atomized Ti-based powders being 73% [size < 25 μm], 61% [25-37 μm], and 50% [37-44 μm]), and establish an SLM parameter (a scan rate of 600 mm/s, a power of 120 W, and an overlap of 10%). The Ti42Zr35Si5Co12.5Sn2.5Ta3 bulk metallic glass composite was successfully fabricated through SLM. This study demonstrates that the TiZrSiCoSnTa system constitutes a promising basis for the additive manufacturing process in terms of preparing biocompatible metallic glass composites into complicated graded foam shapes.

Design Optimization and Mechanical Properties of SiC Particle Reinforced Ti-Based Metallic Glass Matrix Composite.

Ti-based bulk metallic glass (BMG) alloys have attracted widespread attention due to their strong glass forming ability, high specific strength, and good corrosion resistance. However, the poor plasticity of BMGs limits their further application in the aerospace and aircraft fields, as well as others. We optimized the composition of SiC-reinforced, Ti-based metallic glass matrix composites (MGMCs) through finite element modeling (FEM). FEM of MGMCs containing irregularly shaped SiC particles with different contents was conducted. Stress and strain analyses were conducted to evaluate the effect of the particle volume fraction on the mechanical behavior of MGMCs, and an optimization value of 30% was obtained, which is conducive to plasticity improvement. Arc melting copper mold injection casting was used to verify the optimized SiC content. The results show that the electroless nickel plating treatment effectively improves the wettability between SiC particles and the amorphous matrix, enabling the successful preparation of SiC/MGMC with a volume fraction of 29.5% through traditional injection casting. The volume fraction of SiC plays a crucial role in the transition of fracture mode from splitting to shear in MGMCs. After adding lightweight SiC particles, the yield strength, plasticity, modulus, and specific strength were improved by 25%, 1471%, 46%, and 33%, indicating that the use of nickel-plated SiC particles in MGMCs is an effective strengthening and toughening method for BMGs.

“Double-yielding” behavior and progressive β → α → twins transformation in a Ti-based metallic glass matrix composite

A Ti-based metallic glass matrix composite (MGMC) exhibits strong work-hardening ability and superb uniform elongation. At 298 K, the yielding strength (YS) reaches 1100 MPa and the uniform elongation (UE) is 7.8%. The rare "double-yielding" phenomenon occurs at room temperature and disappears at cryogenic temperature. At 77 K, the YS reaches 1550 MPa and the UE is 5.3%. Different deformation mechanisms of martensite transformation and α → twins transformation proceed at room and cryogenic temperatures, respectively. It provides guidance for exploring the effect of martensite transformation in MGMCs and developing high-performance MGMCs.

Microstructure Quantification and Multiresolution Mechanical Characterization of Ti-Based Bulk Metallic Glass-Matrix Composites

Microstructure Quantification and Multiresolution Mechanical Characterization of Ti-Based Bulk Metallic Glass-Matrix Composites

Vacuum infiltration molding and mechanical property of short carbon fiber reinforced Ti-based metallic glass matrix composite

• New vacuum infiltration method using Cu-mold-prepared CF preform is developed. • Electroless-Cu-plated layer dissolves to improve the wettability during infiltration. • Interface microstructure control is achieved by Cu-layer and short-term infiltration. • Ti-based CFRMGMC has obviously improved plasticity together with high-strength. • Randomly and uniformly distributed short CF leads to brittle-ductile transition. The molding process is the key technology for the development of carbon fiber reinforced metallic glass matrix composites (CFRMGMCs), which not only needs to tackle the challenge of the mixing uniformity of carbon fibers, but also should take into account the rapid cooling technology to obtain a fully glassy matrix. Herein, a new vacuum pressure infiltration molding method is developed to fabricate a Ti-based CFRMGMC, in which a copper mold is performed as the container for carbon fiber preforms in addition to being used as a rapid cooling device. In order to prevent the interface reaction between carbon fiber and metal liquid, an electroless copper layer is plated on the surface of carbon fiber. It is found that the thin copper layer is dissolved in the glassy matrix and no crystalline phase is formed on the interface between the fiber and the matrix, showing a good effect on the control of interface microstructure. Meanwhile, electroless copper layer also effectively improves the wettability between the carbon fiber and the titanium alloy melt, thereby improving the infiltration forming ability of the composite material and reducing the tendency to form macroscopic defects. The as-prepared Ti-based CFRMGMC shows a significantly improved plasticity of ∼5 % and a high yield strength of 1880 MPa. The toughening mechanism can be attributed to the random distribution of short carbon fibers in different directions, which originates from the preparing process of carbon fiber preforms. This multi-directional posture is frozen in the glassy matrix and stimulates the multiple shear band behavior of the CFRMGMC. This work sheds lights on the use of carbon fiber in bulk metallic glasses, and is of great significance to the lightweight development and the interface reaction control of CFRMGMCs.

Achieving work hardening by forming boundaries on the nanoscale in a Ti-based metallic glass matrix composite

Achieving work hardening in metallic glass matrix composites (MGMCs) is the key to the extensive use of these attractive materials in structural and functional applications. In this study, we investigated the formation of nanoscale boundaries resulted from the interaction between matrix and dendrites, which favors the work-hardening deformation in an in-situ Ti41Zr32Ni6Ta7Be14 MGMC with β-Ti dendrites in a glassy matrix at room temperature. The microstructures of samples after tension were observed by high-resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD). The work-hardening mechanism of the present composites involves: (1) appearance of dense dislocation walls (DDWs), (2) proliferation of shear bands, (3) formation of boundaries on the nanoscale, and (4) interactions between hard and soft phases. A theoretical model combined with experimental data reveals the deformation mechanisms in the present work, proving that the in-situ dendrites with outstanding hardening ability in the glass matrix can provide the homogeneous deformation under tensile loading at room temperature.

Universally scaling Hall-Petch-like relationship in metallic glass matrix composites

Ti-based metallic glass matrix composites (MGMCs) with a composition of Ti50Zr20V10Cu5Be15 (atomic percent, at. %) exhibit excellent tensile ductility and distinct work-hardening capability. A dislocation pile-up model (DPM) has been established to elaborate the dislocation motion near the yield point and to theoretically derive a linear Hall-Petch-like relationship between the yield strength, σ, and the inverse square root of the diameter of dendrite arms, d−1/2. The materials constant, k, in the present Hall-Petch-like relationship can be calculated on the basis of the pile-up model, and is very close to the experimental value. The hardness variation in the dendrites and the strengthening effect from unloading-reloading tests prove the reasonability of the DPM during tension. The Hall-Petch-like relationship is verified for a variety of MGMCs, whose plastic deformation is only dominated by dislocation motion. Mean-field theory (MFT) has been first utilized to build a relationship between the critical diameter of dendrites, dc, and the composition in MGMCs with the similar atomic percentages of low solubility elements. By tuning the composition, one can universally scale the Hall-Petch-like relationship, and accurately predict the yield strength of such in-situ MGMCs.

The Corrosion Behavior of Ti-Based Metallic Glass Matrix Composites in the H2SO4 Solution

In-situ metallic glass matrix composites (MGMCs) are a new kind of promising structural engineering material. In this study, a comprehensive study about the corrosion behavior of in-situ Ti46Zr20V12Cu5Be17 MGMCs versus their size was conducted. It is interesting to find that the large sample exhibits a more excellent corrosion resistance than the small sample in the 10% H2SO4 solution both in chemical and electrochemical tests at room temperature. Furthermore, the results obtained from X-ray photoelectron spectra (XPS) demonstrate that the quality of the passive film formed on the large-sized sample is indeed superior to the small-sized sample. Based on (scanning electron microscope) SEM observation, the possible mechanisms of the observed phenomenon have been discussed in the present study.

Cryogenic mechanical property and deformation behavior of a Ti-based metallic glass matrix composite by three point bending tests

In this paper, cryogenic mechanical property and deformation behavior of a Ti-based metallic glass matrix composites (MGMCs) containing the in-situ β dendrite phase were investigated by three point bending tests from 298 K to 77 K. The result demonstrated that the flexural strength increased with the decreasing applied temperature, e.g. the flexural yielding strength increased by 32.6% from 1890 MPa at 298 K to 2506 MPa at 77 K, which has been fitted as an exponential function on the basis of the modified Zerilli and Armstrong (Z–A) model. It is found that the β dendrite phase lost its activity gradually and failed to promote shear-bands multiplication with decreasing testing temperature, leading to plasticity of the MGMC decreased. The deformation mechanism was discussed according to the fracture characteristics of the composite deformed at different cryogenic temperature.

Corrosion behavior and pitting susceptibility of in-situ Ti-based metallic glass matrix composites in 3.5 wt.% NaCl solutions

The Ti62Zr12V13Cu4Be9, Ti58Zr16V10Cu4Be12, Ti46Zr20V12Cu5Be17, and Ti40Zr24V12Cu5Be19 metallic glass matrix composites (MGMCs) were prepared by copper mould casting. The corrosion resistance and the pitting susceptibility of Ti-based MGMCs were tested on their cross-sectional areas in 3.5wt.% NaCl solutions by potentiodynamic polarization measurements. The composites with lower Ti contents (Ti40Zr24V12Cu5Be19 and Ti46Zr20V12Cu5Be17) exhibit a low resistance to the chloride induced pitting and local corrosion. The preferential dissolution of amorphous matrix is explained by the high chemical reactivity of beryllium element compared to that of stable dendrites and by the detected lower Ti and V contents. However, fairly good passivity was found in the composite with higher Ti contents (Ti62Zr12V13Cu4Be9). XPS measurements revealed that protective Ti-enriched oxide film was formed on the composite surface, additionally, lower content of beryllium element in amorphous matrix hinder the selective corrosion of amorphous matrix. The assessment of experimental observation leads to a proposed corrosion mechanism involving selective dissolution of amorphous matrix and chloride induced pitting process.

Twinning-induced plasticity (TWIP) and work hardening in Ti-based metallic glass matrix composites

The present study demonstrates that Ti-based metallic glass matrix composites (MGMCs) with a normal composition of Ti43Zr32Ni6Ta5Be14 containing ductile dendrites dispersed in the glass matrix has been developed, and deformation mechanisms about the tensile property have been investigated by focusing on twinning-induced plasticity (TWIP) effect. The Ti-based MGMC has excellent tensile properties and pronounced tensile work-hardening capacity, with a yield strength of 1100 MPa and homogeneous elongation of 4%. The distinguished strain hardening is ascribed to the formation of deformation twinning within the dendrites. Twinning generated in the dendrites works as an obstacle for the rapid propagation of shear bands, and then, the localized necking is avoided, which ensures the ductility of such kinds of composites. Besides, a finite-element model (FEM) has been established to explain the TWIP effect which brings out a work-hardening behavior in the present MGMC instead of a localized strain concentration. According to the plasticity theory of traditional crystal materials and some new alloys, TWIP effect is mainly controlled by stacking fault energy (SFE), which has been analyzed intensively in the present MGMC.

Development of in-situ β-Ti reinforced Be-free Ti–based bulk metallic glass matrix composites

In this paper, in-situ β-Ti phase reinforced (Al, Ni, Be)-free Ti-based bulk metallic glass matrix composites (BMGMCs) were developed by microalloying Mo. The BMGMCs showed higher fracture strength and larger plastic strain than the monolithic glassy counterpart and other Be-free Ti-based BMGMCs, under both compression and bending tests. The ductile and soft β-Ti secondary phase appeared to hinder the rapid propagation of the main shear band, improving the plasticity. Furthermore, the size and interparticle spacing of the secondary β-Ti were very close to the processing zone size, further stabilizing the shear band against developing into cracks and thus improving mechanical properties. But under tension, no obvious ductilization was observed for the BMGMCs, maybe resulting from the lower volume fraction of β-Ti phase because of higher cooling rate during the fabrication for them. Further work should be focused on optimizing the composition and increasing the volume fraction of β-Ti phase and sample size.

Enhancing the compressive and tensile properties of Ti-based glassy matrix composites with Nb addition

Combining copper mold suction-casting and copper mold pouring-casting techniques, in-situ Ti-based bulk metallic glass matrix composites (Ti0.45Zr0.31Be0.17Cu0.07)100−xNbx (x=4, 6, 8 and 10) with Φ=3mm and composites (x=6, 8 and 10) with Φ=8mm are fabricated in order to perform compressive and tensile tests, respectively. The volume and size of crystalline β-Ti(Zr, Nb) dendrites of these composites increase with the increasing Nb content, resulting in the improvement of compressive and tensile properties of the composites. Among these composites, Ti40.5Zr27.9Be15.3Cu6.3Nb10 (x=10) has the highest compressive ultimate strength of 2756MPa and plastic strain of 39.5%; meanwhile, it possesses a high tensile ultimate strength of 1428MPa and a large tensile plasticity of 7.7%. As indicated by the SEM micrographs, in compressive tests, the more branched the dendrites, the more shear bands, and the higher compressive strength and plasticity of these composites. In tensile tests of Ti40.5Zr27.9Be15.3Cu6.3Nb10 (x=10), ductile fracture features, including the macroscopic necking, fracture of ligament, vein patterns and sliding traces, are observed. The reason of the excellent mechanical properties of the measured composites is that the propagation of shear bands and cracks are impeded by β-Ti(Zr, Nb) dendrites, and then be confined in a small space.

Beryllium-distribution in metallic glass matrix composite containing beryllium

The morphologies, sizes, compositions and volume fractions of dendritic phases in in situ Ti-based metallic glass matrix composites (MGMCs) containing beryllium (Be) with the nominal composition of Ti47Zr19Cu5V12Be17 (mole fraction, %) were investigated using XRD, SEM, EBSD, TEM, EDS and three-dimensional reconstruction method. Moreover, visualized at the nanoscale, Be distribution is confirmed to be only present in the matrix using scanning transmission electron microscopy–electron energy loss spectroscopy (STEM–EELS). Based on these findings, it has been obtained that the accurate chemical compositions are Ti28.3Zr19.7Cu8V6.4Be37.6 (mole fraction, %) for glass matrix and Ti62.4Zr18.4Cu2.6V16.6 (mole fraction, %) for the dendritic phases, and the volume fractions are 38.5% and 61.5%, respectively. It is believed that the results are of particular importance for the designing of Be-containing MGMCs.

Effect of strain rates on deformation behaviors of an in situ Ti-based metallic glass matrix composite

Quasi-static and dynamic deformation behaviors of an in situ dendrite-reinforced metallic glass matrix composite: Ti56Zr18V10Cu4Be12 were investigated. Upon quasi-static compression, the composite exhibits distinguished work hardening, accompanied by the ultimate strength of 1290 MPa and the plasticity of 20 %. The improved plasticity is attributed to the multiplication of shear bands within the glass matrix and pileups of dislocations within the dendrites. Upon dynamic compression, the stable plastic flow prevails and the yielding stress increases with the strain rate. The macroscopic plasticity decreases considerably, since the shear bands cannot be effectively hindered by dendrites with deteriorated toughness. The dendrite-dominated mechanism results in the positive strain-rate sensitivity, and the Cowper–Symonds model is employed to depict the strain-rate dependency of yielding strength.

Towards an understanding of tensile deformation in Ti-based bulk metallic glass matrix composites with BCC dendrites.

The microstructure and tension ductility of a series of Ti-based bulk metallic glass matrix composite (BMGMC) is investigated by changing content of the β stabilizing element vanadium while holding the volume fraction of dendritic phase constant. The ability to change only one variable in these novel composites has previously been difficult, leading to uninvestigated areas regarding how composition affects properties. It is shown that the tension ductility can range from near zero percent to over ten percent simply by changing the amount of vanadium in the dendritic phase. This approach may prove useful for the future development of these alloys, which have largely been developed experimentally using trial and error.

Effect of temperature on mechanical properties of Ti-based metallic glass matrix composite

Systematic mechanical behaviors were investigated in a Ti-based metallic glass matrix (MGM) composite containing the in-situ β-dendrite phase at 100 K–298 K. We found that the yielding strength increased but the plastic strain decreased with a decrease temperature. The sharp ductile to brittle transition occurred at 100 K. The MGM composite exhibits the large work-hardening behavior at 298 K, but all sample display the work-softening behavior below 298 K. The nominal work-hardening parameter was employed to express the dependence of mechanical properties on temperatures including the brittle failure, the work-hardening and work softening behaviors. It may provide a useful way to evaluate the dependence of mechanical properties on temperatures of MGM composite.

Dynamic mechanical properties of a Ti-based metallic glass matrix composite

Dynamic mechanical behavior of a Ti50Zr20Nb12Cu5Be13 bulk metallic glass composite was investigated using mechanical spectroscopy in both temperature and frequency domains. Storage modulus G′ and loss modulus G″ are determined by temperature, and three distinct regions corresponding to different states in the bulk metallic glass composite are characterized. Physical parameters, such as atomic mobility and correlation factor χ, are introduced to analyze dynamic mechanical behavior of the bulk metallic glass composite in the framework of quasi-point defects (QPD) model. The experimental results are in good agreement with the prediction of QPD model.

High strain rate compressive behavior of Ti-based metallic glass matrix composites

The compression behaviors of Ti-based metallic glass matrix composites with dendrites scale were tested at different loading rates. It was found that the composites exhibited not only high strength, but also large plasticity under quasi-static compression. Under the dynamic loading, however, the TZ1 alloy with fine dendrites demonstrated a catastrophic failure. Although both the strength and plasticity decreased for the TZ2 composite sample with coarse dendrite, the total strain is over 7%. Discussions on the strain rates and dendrite scale are provided by analyzing the effects of dendrite, which can present the possible deformation mechanism of the composites.

Investigation of the microcrack evolution in a Ti-based bulk metallic glass matrix composite

The initiation and evolution behavior of the shear-bands and microcracks in a Ti-based metallic-glass–matrix composite (MGMC) were investigated by using an in-situ tensile test under transmission electron microscopy (TEM). It was found that the plastic deformation of the Ti-based MGMC related with the generation of the plastic deformation zone in crystalline and shear deformation zone in glass phase near the crack tip. The dendrites can suppress the propagation of the shear band effectively. Before the rapid propagation of cracks, the extending of plastic deformation zone and shear deformation zone ahead of crack tip is the main pattern in the composite.