Bulk Metallic Glass Matrix Composites Research Articles

Effect of cooling rate during solidification on structure and mechanical properties of Cu45Zr48Al7 glass-forming alloy

The CuZr-based bulk metallic glass matrix composites have attracted great attention in recent years owing to their unique mechanical properties compared to bulk glassy samples. The vital effect of B2 CuZr phase on mechanical properties was previously confirmed in CuZr-based alloys with equiatomic concentrations of copper and zirconium. In this paper, the structures and mechanical properties of the Cu45Zr48Al7 alloy, which has hypereutectoid composition with respect to stoichiometric B2 CuZr phase, were studied. This alloy exhibits high glass-forming ability, but low tendency to form the B2 CuZr phase during solidification. However, we demonstrated that depending on the cooling rate during solidification, governed by sample diameter, either bulk metallic glass or bulk metallic glass matrix composite can be produced. In order to allow partial crystallization of the B2 phase during solidification with the volume fraction allowing to observe the strain hardening effect, the minimum cooling rate should be lower than 40 K/s. The composite consisting of a glassy outer layer and a crystalline core composed of the B2 phase exhibits fracture strength of the same level as the bulk glassy sample (above 1800 MPa) obvious work-hardening with a plastic deformation of about 6%.

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.

Synthesis and mechanical behavior of in-situ porous Ti particle reinforced Mg-Cu-Gd-Ag bulk metallic glass matrix composite

The in-situ porous Ti particle reinforced Mg-based bulk metallic glass matrix composites have been successfully prepared via dealloying reaction in metallic melt. The microstructure, thermal properties and mechanical properties of the composites containing various volume fraction of porous Ti particles were investigated in detail. It is shown that with higher content of porous Ti particles, the glass-forming ability of the composites degrades gradually with the precipitation of fine crystalline phases among the glassy matrix. When the volume fraction of porous Ti particle is 26.3 vol%, the composite shows an fracture strength of 1125 MPa, 14.1 % higher than the monolithic glassy base alloy. Furthermore, the composite also exhibit an improved plastic strain of 0.94 %. The in-situ porous Ti particle and the submicron crystalline phase can hinder the rapid propagation of the main shear bands, causing the generation of multiple shear bands. It is found that abundant shear bands are formed around the porous Ti particle. The present synthesis strategy of in-situ porous reinforcing phase will contribute to the breakthrough in designing novel metal matrix composites.

Modelling and Simulation of Microstructural Evolution in Zr Based Bulk Metallic Glass Matrix Composites (Bmgmc) in Additive Manufacturing – a Proposal, Opinion and Prospect

Modelling and Simulation of Microstructural Evolution in Zr Based Bulk Metallic Glass Matrix Composites (Bmgmc) in Additive Manufacturing – a Proposal, Opinion and Prospect

Development of Bulk Metallic Glass Matrix Composites (MGMC) by Inoculation and Their Laser Additive Manufacturing 2

Development of Bulk Metallic Glass Matrix Composites (MGMC) by Inoculation and Their Laser Additive Manufacturing 2

Development of Bulk Metallic Glass Matrix Composites (MGMC) by Inoculation and Their Laser Additive Manufacturing 4

Development of Bulk Metallic Glass Matrix Composites (MGMC) by Inoculation and Their Laser Additive Manufacturing 4

Microstructural Evolution in Zr based Bulk Metallic Glass Matrix Composites (BMGMC) in Additive Manufacturing - Modeling and Simulation

Microstructural Evolution in Zr based Bulk Metallic Glass Matrix Composites (BMGMC) in Additive Manufacturing - Modeling and Simulation

Development of Bulk Metallic Glass Matrix Composites (MGMC) by Inoculation and Their Laser Additive Manufacturing

Development of Bulk Metallic Glass Matrix Composites (MGMC) by Inoculation and Their Laser Additive Manufacturing

Development of Bulk Metallic Glass Matrix Composites (MGMC) by Inoculation and Their Laser Additive Manufacturing 3

Development of Bulk Metallic Glass Matrix Composites (MGMC) by Inoculation and Their Laser Additive Manufacturing 3

Orientation Relationships in Inoculated and Non Inoculated Zr Based Bulk Metallic Glass Matrix Composites for Laser Additive Manufacturing

Orientation Relationships in Inoculated and Non Inoculated Zr Based Bulk Metallic Glass Matrix Composites for Laser Additive Manufacturing

Effects of Non-metallic Elements B, Si and Te on the Formation, Mechanical Properties and Microstructure of Cu-Zr-based Amorphous Alloys

In recent years, the B2 CuZr crystals have been successfully introduced into the matrix of amorphous alloy, resulting in the formation of bulk metallic glass composite. The in situ fabricated amorphous composites have exhibited not only good plasticity but high yield strength in conjunction with obvious work-hardening behavior, which has attracted great attention. However, until now microalloying elements are mainly metallic elements and less studies have been conducted on the non-metallic elements on the glass-forming ability and mechanical properties of Cu-Zr-based metallic glasses and their composites. In this work, the influence of non-metallic elements B, Si and Te on the structural evolution and the mechanical properties in Cu-Zr-based metallic glass matrix composites were studied. It was found the that the prepared bulk metallic glass matrix composites show high strength and plasticity at room temperature. This work provides a good experimental basis for future application.

Fracture toughness of a rejuvenated β-Ti reinforced bulk metallic glass matrix composite

• Cryothermal cycling is performed on embrittled bulk metallic glass composite. • Plasticity of BMGC examined using nanoindentation, DSC and compression tests. • Mode I notch toughness of CTC treated BMGC is same as brittle BMGC. • Rejuvenation is hampered by chemical short range ordering of constituents in amorphous matrix. A β-Ti dendrite reinforced Zr-based bulk metallic glass composite (BMGC) was found to be brittle when cast in a large size. The reasons for the embrittlement and the effectiveness of the cryothermal cycling (CTC) treatment in restoring the mode I fracture toughness are examined. Plasticity in all the CTC treated BMGC is estimated from the distribution and occurrence of pop-ins in nanoindentation tests and by measuring the magnitude of enthalpy of relaxation (Δ H rel ) via differential scanning calorimetry (DSC). This is further validated by examining the strain-to-failure ( ε f ) in compression tests. Mode I fracture behaviour of the as-cast embrittled BMGC and the CTC treated BMGC, which exhibits maximum plasticity, is examined. Results show that both BMGCs are equally brittle and exhibit 5 times lower notch toughness ( K QJ ) than their tougher counterpart. Post-facto imaging of the side surfaces reveals the absence of notch-tip plasticity in both BMGCs. The lack of notch tip plasticity of CTC treated BMGC, despite exhibiting signatures of plasticity in nanoindentation and higher Δ H rel is rationalized by reassessing the origin of pop-ins in nanoindentation tests and describing the variations in chemical and topological short range ordering during CTC, respectively. Implications of these results in terms of improving the fracture toughness of structurally relaxed BMGCs via CTC are discussed.

Fabrication and mechanical property of three-dimensional carbon fiber reinforced Mg-based bulk metallic glass matrix composite

Carbon fiber (CF) reinforced bulk metallic glass matrix composites (BMGMCs) have received widespread attention due to their light weight, but subsequent development is facing urgent challenges of uncontrollable interface reaction and poor plasticity. Here, we report a three-dimensional CF-reinforced Mg-based BMGMC, which significantly improves the microstructure and compressive plasticity by adjusting the pressure infiltration parameters. It has been found that the electroless copper plating improves the wettability of the CF and the melt without inducing the crystallization of the matrix, in spite of the partially dissolving and diffusing of the coating to the matrix. Under a similar infiltration pressure difference, high vacuum conditions are beneficial to reduce the capillary resistance of the porous CF preform, thereby improving the formability of BMGMC. Compression test results prove that the introduction of three-dimensional CF effectively improves the plasticity of the composite material and reduces its brittleness tendency. It can be attributed to the fact that the carbon fibers distributed in different directions effectively bridge the multi-directional cracks and prevent the early rapid shear band propagation. The present work provides meaningful enlightenment for the development of CF-reinforced BMGMC materials.

Annealing-induced phase transitions in a Zr–Ti–Nb–Cu–Ni–Al bulk metallic glass matrix composite containing quasicrystalline precipitates

Abstract The phase formation of a copper-mold-cast Zr60Ti2Nb6Cu14 Ni9Al9 alloy has been investigated upon cooling from the melt as well as upon annealing of as-cast specimens. The different states of the samples are characterized by X-ray diffraction, optical and electron microscopy, and differential scanning calorimetry. The cooling rate as realized upon copper-mold casting leads to micrometer-sized quasicrystals, which are embedded in a glassy phase. The thermal stability ΔTx of the supercooled liquid state of the glassy phase that forms near to the wall of the copper mold, differs from that of the glassy matrix in the center of the rod due to different compositions of the glassy phase. This is a consequence of the change in local cooling conditions, which affects the phase formation upon solidification as well as the subsequent transformation behavior of the alloy upon constant-rate heating.

Penetration Failure Mechanism of Multi-Diameter Tungsten Fiber Reinforced Zr-Based Bulk Metallic Glasses Matrix Composite Rod

In order to increase the penetration ability of tungsten fiber-reinforced Zr-based bulk metallic glasses matrix composite rod, two multi-diameter tungsten fiber-reinforced Zr-based bulk metallic glasses matrix composites (MD-WF/Zr-MG) are designed. In MD-WF/Zr-MG-I, the diameters of tungsten fiber (WF) increase gradually from the inside to outside, which is the opposite in MD-WF/Zr-MG-II. Penetration experiment of two kinds of MD-WF/Zr-MG rods into rolled homogeneous armor (RHA) steel target from 1470 m/s to 1630 m/s is conducted. The average penetration depth of the MD-WF/Zr-MG-II rod is higher than that of the MD-WF/Zr-MG-I rod. Penetration failure modes of MD-WF/Zr-MG-I and MD-WF/Zr-MG-II rods are bending, backflow of WFs and shear failure respectively. The failure mode of MD-WF/Zr-MG is affected by the bend spaces and the ultimate bending diameters of WFs. If the bend spaces of all WFs are equal or larger than their ultimate bending diameters, the penetration failure mode is the bending and backflow of WFs, oppositely the penetration failure mode is the shear failure. The MD-WF/Zr-MG rod with shear failure exhibits high penetration ability because of low penetration resistance and little residual material in the crater. When designing MD-WF/Zr-MG, bend spaces of a part of WFs should be smaller than their ultimate bending diameter to cause shear failure.

Structure and Mechanical Properties of Cu45zr48al7 Bulk Metallic Glass and Metallic Glass Matrix Composites

Structure and Mechanical Properties of Cu45zr48al7 Bulk Metallic Glass and Metallic Glass Matrix Composites

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

Synergetic toughening mechanism of spherical α-La phases and micron-sized AlLa3 intermetallic in La-based bulk metallic glass composite

A La74Al14Cu6Ni6 bulk metallic glass matrix composite (BMGMC) with in situ spherical α-La phases and micron-sized AlLa3 intermetallic compounds is prepared by adjusting the processing parameters and presents a good combination of high strength and plasticity. Compared with conventional single α-La dendrite-reinforced La74Al14Cu6Ni6 BMGMCs that have a low fracture strength and plasticity, the obtained composite shows a significant plastic strain of 17% and a high fracture strength of 566 MPa. The results show that the formation of ductile bulky spherical α-La phases and hard AlLa3 intermetallic compounds can effectively hinder the rapid propagation of single shear band, and the synergistic effect of the two phases accounts for the significant increase in plasticity. Furthermore, in situ formed AlLa3 intermetallic compounds with a hardness of 238 HV, which has strong interaction with multiple shear bands, dramatically improve the fracture strength of the composite.

In-situ synthesis of Mg-based bulk metallic glass matrix composites with primary α-Mg phases

Herein, we systematically investigate the in-situ synthesis and mechanical properties of Mg-based bulk metallic glass matrix composites (BMGMCs). From a well-known Mg65Cu25Gd10 bulk glass former, a series of Mg65+xCu20–2x/3Zn5Gd10−x/3 (x = 0–18 at%) alloys are systematically designed and Mg-rich (>77 at% Mg) glassy/crystalline matrix composites containing primary α-Mg phases are successfully developed. Mg77Cu12Zn5Gd6 BMGMC (x = 12 at%) exhibits over two times higher compressive fracture strength (773 ± 20.6 MPa) and specific strength (2.6 × 105 N m kg−1) than commercial Mg alloys such as AZ31 or AZ91. In particular, compared with monolithic Mg-based BMGs, the BMGMC displays obvious yielding, serrated plastic flow and plastic strain of 0.22 ± 0.02%. This result is attributed to the dispersed primary α-Mg phases which prevent the rapid propagation of shear bands and promote the formation of multiple shear bands. The Mg-rich crystalline matrix composites (x = 14-18 at%) containing primary α-Mg phases exhibit an enhancement in the plastic strain (from 0% to 1.51%) and pronounced work hardening at the expense of yield strength (<500 MPa) due to the absence of the amorphous phase. These results would give us a promising strategy to fabricate Mg-based BMGMCs with high specific strength and enhanced plasticity for lightweight structural applications.

Shear fracture in bulk metallic glass composites

Fracture behavior of bulk metallic glass matrix composites (BMGCs) with both transforming and non-transforming β-Ti dendrites under shear and opening modes was examined. Experimental results show that the fracture toughness of all three BMGCs is considerably lower in mode II than in mode I, due primarily to the shear dominant stress state in the former, which renders easy shear band initiation. However, stable crack growth in mode I is insignificant whereas it is considerable in mode II. The toughness of BMGCs reinforced with coarse but non-transforming dendrites in both the modes is higher than the respective values in BMGCs with transforming β-Ti inspite of their ability to strain harden and hence enhanced ductility. Fracture surface features and shear band patterns at notch tips of both mode I and mode II specimens indicate that despite the interactions of dendrites with the shear bands, the fracture criterion and mechanism of BMGCs is identical to that in BMGs. The differences in the fracture behaviour of these BMGCs is rationalized by considering the effect of relaxation enthalpy of the amorphous matrices in addition to the length scale and transforming tendency of the dendrites on the transformation of a shear band into a crack. Implications of these results in terms improving the fracture toughness of BMGCs with transforming dendrites is discussed.