Properties Of Zr-based Metallic Glass Research Articles

Microstructure and mechanical properties of SiC particle reinforced Zr-based metallic glass surface composite layers produced by laser alloying

Metallic glasses (MGs) are a promising candidate for advanced structural applications due to their superior mechanical properties. Improving their surface mechanical properties would be of great importance for promoting their structural and functional applications. In this study, SiC particles were used as the reinforcement to improve the mechanical properties of Zr-based MG via laser surface alloying. The influences of the average laser power and overlap ratio between neighboring laser processing lines on the microstructure and mechanical properties of the laser-alloyed surface layer were investigated. The experimental results indicated that ZrC and SiC phases were successfully introduced into the MG matrix by laser surface alloying, and the content of these two hard ceramic phases was dependent on the laser processing parameters. The formed laser-alloyed surface layers exhibited a significant improvement in overall hardness compared with the as-cast specimen. At a relatively high overlap ratio of 70%, the average hardness of the MG matrix within the laser-alloyed surface layer reached 28.91 GPa, which was three times higher than that of the as-cast specimen (6.46 GPa). Furthermore, the microstructural characteristics and mechanical properties of the cross-sections of the laser-alloyed samples were characterized. The thickness of the laser-alloyed surface layer reached several tens of microns, and the SiC particles were uniformly dispersed in the whole laser-alloyed surface layer. This study confirms the feasibility for improving the mechanical properties of MGs by laser surface alloying, which is expected to broaden the application of MGs as structural and functional components under harsh severe conditions.

Microstructures and mechanical properties of Zr-based metallic glass ablated by nanosecond pulsed laser in various gas atmospheres

The surface with micro-convex prepared by laser ablation is beneficial to improving the functional properties of metallic glasses (MGs). However, accompanied by the formation of micro-convex, surface hardness of the ablated area generally decreases due to the softening effect caused by laser thermal shock. Previous studies have shown that the mechanical properties of laser-ablated MG surface are significantly different when using different gas atmospheres. In this study, a comparative investigation was performed to analyze the influence of gas atmosphere (i.e. argon, nitrogen, and air) on the formation of micro-convex as well as its surface characteristics and mechanical properties. Experimental results showed that the atmosphere type did not affect the formation of micro-convex, but significantly affected the surface morphology and element composition of the laser-ablated area. The element analysis and Raman spectral measurements indicated that laser ablation in nitrogen or air atmosphere resulted in local nitridation or oxidation. The results of nanoindentation tests demonstrated that laser ablation in nitrogen or air atmosphere also resulted in surface hardness inhomogeneity, i.e., softening and hardening effects coexist in the ablated area, which could be attributed to the combined influence of laser thermal shock, the introduction of secondary phase as well as laser ablation induced loose structure.

The Evolution of Micromechanical Properties for Zr-Based Metallic Glass Induced by Laser Shock Peening

The micromechanical properties of Zr-based metallic glass (MG) induced by laser shock peening (LSP) were studied through the use of nanoindentation. The serrations in representative load-displacement (P-h) curves exhibited a transformation from stairstep-like to ripple-shaped from untreated zone to shock region, which implied an increase in plastic deformation ability of material after LSP. Significant hardening was also observed in the impact zone, which can be attributed to the effect of compressive residual stress. Both increase in hardness and plastic deformation ability in shock region indicate the excellent effect of LSP on the micromechanical properties of investigated Zr-based MG, which provide a new way to study the deformation mechanism in metallic glasses and a further understanding of plasticization.

Abnormal change in dynamic mechanical behavior of metallic glass by laser shock peening

Laser shock peening (LSP) has been shown to be an effective technique to improve the plasticity of metallic glasses (MGs) by inducing residual stress and structural rejuvenation. However, the microstructural evolution and viscoelastic properties of MGs after LSP remain largely unknown. In this paper, the dynamic mechanical properties of Zr-based MG before and after LSP treatment were investigated. An abnormal increase of storage modulus near the glass transition temperature (Tg) was observed after LSP. An increased deviation between the dynamic mechanical result and the quasi-point defect (QPD) theory prediction was also observed after the LSP treatment. A competing mechanism between the liquid-like region change and the pre-existing fringe-like precipitations is proposed to explain the unusual dynamic behaviors of MGs after LSP treatment. The results provide insightful information about the microstructural changes and viscoelastic properties of the MGs after LSP.

Effect of Deformation Conditions on Mechanical Properties of Zr-based Metallic Glasses

In this paper, the effects of different strain rate(1×10-5 s-1, 5×10-5 s-1, 1×10-4 s-1, 5×10-4 s-1, 1×10-3 s-1) and aspect ratio(1:1, 1.5:1, 2:1, 2.5:1, 3:1) on mechanical properties of Zr-based metallic glasses at room temperature were investigated. The results indicate that as the strain rate increases, the plastic strain and compressive strength of the specimens gradually decrease. The specimen with the strain rate of 1×10-5 s-1 exhibits the higher plastic strain of 10.25 %, compressive strength of 2002 MPa and fracture strength of 1999 MPa. In addition, accompanied with the increase in aspect ratio, the plastic strain of the specimens declines from 25.42 % to 1.97 %, meanwhile, the compressive strength and fracture strength of the specimens also present declining trend.

The coupling effects of laser thermal shock and surface nitridation on mechanical properties of Zr-based metallic glass

Laser processing is a versatile tool for applications in the field of metallic glasses (MGs). Previous studies reported that surface nitridation, i.e. the formation of ZrN phase, occurred when laser irradiation of Zr-based MG was performed in nitrogen gas. Additionally, it was reported that laser thermal shock usually softened the irradiated surface. Therefore, the coupling effects of laser thermal shock and surface nitridation on mechanical characteristics of Zr-based MG should be further clarified. For this purpose, in this study, laser irradiation of Zr-based MG was conducted under various experimental conditions, followed by evaluating the surface characteristics by X-ray diffraction (XRD), nanoindentation, and energy-dispersive X-ray (EDX) spectroscopy. Experimental results indicated that the nanoindentation hardness, serrated flow, and surface shear bands were significantly affected by laser irradiation in nitrogen gas. Both surface softening and hardening were observed which depended on the experimental conditions. A competition mechanism between laser thermal shock and the introduction of ZrN phase was employed to rationalize these results. Furthermore, the affecting layer of ZrN phase along the depth direction was measured by EDX. The obtained results suggest a new method to introduce secondary phase into Zr-based MG surface and further to tune the mechanical characteristics of MGs.

Effect of hydrogen addition on the mechanical properties of Zr-based metallic glass

In this study, correlation between the softening phenomenon and free volume content in hydrogenated Zr57Al10Cu15.4Ni12.6Nb5 amorphous metal through instrumented nanoindentation tests and differential scanning calorimetry (DSC) analysis is reported. X-ray diffraction analyses revealed that hydrogen addition gives rise to the development of large void structures that facilitate the local atomic displacement. The mechanical characterization using nanoindentation showed that hydrogen addition may induce the softening of Zr-based metallic glasses even for high Zr content. The shear softening of Zr57Al10Cu15.4Ni12.6Nb5 ribbons is attributed to the weakness of atomic cohesion due to the squeezing and mobility of hydrogen atoms. The resistance to hydrogen embrittlement combined with high thermal stability may increases the possibilities of potential use of Zr57Al10Cu15.4Ni12.6Nb5 amorphous alloy as good metal membrane.

The Microstructural Evolution and Mechanical Properties of Zr-Based Metallic Glass under Different Strain Rate Compressions.

In this study, the high strain rate deformation behavior and the microstructure evolution of Zr-Cu-Al-Ni metallic glasses under various strain rates were investigated. The influence of strain and strain rate on the mechanical properties and fracture behavior, as well as microstructural properties was also investigated. Before mechanical testing, the structure and thermal stability of the Zr-Cu-Al-Ni metallic glasses were studied with X-ray diffraction (XRD) and differential scanning calorimeter. The mechanical property experiments and microstructural observations of Zr-Cu-Al-Ni metallic glasses under different strain rates ranging from 10−3 to 5.1 × 103 s−1 and at temperatures of 25 °C were investigated using compressive split-Hopkinson bar (SHPB) and an MTS tester. An in situ transmission electron microscope (TEM) nanoindenter was used to carry out compression tests and investigate the deformation behavior arising at nanopillars of the Zr-based metallic glass. The formation and interaction of shear band during the plastic deformation were investigated. Moreover, it was clearly apparent that the mechanical strength and ductility could be enhanced by impeding the penetration of shear bands with reinforced particles.

Effect of the metallic glass volume fraction on the mechanical properties of Zr-based metallic glass reinforced with porous W composite

The mechanical properties of both as-cast and as-extruded Zr-based metallic glass reinforced with tungsten composites with 33, 28, and 21 vol. % of metallic glass were investigated under quasi-static compression at strain rates from 10−4s−1 to 10−1s−1. These two types of composites exhibited a strain rate sensitivity exponent that increased with the increase of the tungsten volume fraction. Compared to the composites with 33 and 21 vol. % of the metallic glass, the two types of composites with 28 vol. % of the metallic glass phase exhibited superior fracture energies. The in-situ compression test on the as-cast composites using high-energy synchrotron X-ray diffraction (HEXRD) revealed that the yield stress of the tungsten phase increased with a decrease in the metallic glass volume fraction. The as-cast composite with 28 vol. % of the metallic glass exhibited relatively great mechanical properties compared to the composites that contained 33 and 21 vol. % of the metallic glass. This result was attributed to the great coupling of the load distribution between the two phases and the high lattice strain in the tungsten phase.

Correlation between strain-rate-related mechanical properties of Zr-based metallic glass and casting temperature

Abstract

Effect of spraying condition on property of Zr-based metallic glass coating by gas tunnel type plasma spraying

Metallic glass has excellent functions such as high strength and high corrosion resistance. However, as metallic glass is expensive, a composite material is preferred for better cost performance. Thermal spraying is one of the potential candidates to produce such metallic glass composites. Gas tunnel type plasma spraying is useful in obtaining high quality ceramic coatings because it can easily control the condition of spraying powder. In this study, Zr-based metallic glass (Zr55–Cu30–Al10–Ni5) coatings were produced by gas tunnel type plasma spraying, and the effect of spraying conditions on the properties of Zr-based metallic glass coating was investigated. Dense Zr-based metallic glass coatings of more than 200 μm in thickness were prepared with a Vickers hardness of about Hv = 550 at a plasma current of 250 A, and the amorphous phase of this metallic glass coating appeared to remain in good condition.

Effects of casting temperature on mechanical properties of Zr-based metallic glasses

The effects of casting temperature on microstructure and mechanical properties of as-cast 3mm-diameter Zr64.9Al7.9Ni10.7Cu16.5 and Zr47Cu37.5Ag7.5Al8 alloys were investigated. It was found that crystalline phases were precipitated in amorphous matrix as casting temperature increased. The compressive strength and Hv of as-cast Zr64.9Al7.9Ni10.7Cu16.5 and Zr47Cu37.5Ag7.5Al8 alloys increased slightly when casting temperature increased. However, ultrahigh casting temperature resulted in formation of hard crystalline phase in metallic glass matrix, which caused increase of hardness and density, but decrease of compressive strength.

Cooling rate dependent as-cast microstructure and mechanical properties of Zr-based metallic glasses

In this article, wedge chill casting is used to provide a variation of the cooling rate for the study of cooling rate-dependent as-cast microstructure and mechanical properties of Zr-based metallic glasses with and without yttrium doping. In-situ formed crystalline phases and crystallization sequence are realized in the context of the cooling rate. Macro-hardness is studied via the Brinell ball indentation and the contact morphology is discussed on the basis of microstructure analysis.

Environmental properties of Zr-based metallic glasses and nanocrystalline alloys

Zr-Cu-Ni-Al belongs to the best glass forming systems known; these glasses are suitable as precursor material for nanocrystalline alloys. For an application as hydrogen storage materials for example it is of great interest to know more about these metastable materials in regard to their environmental properties. Corrosion as studied by a salt spray test or anodic polarization in aqueous solutions exhibit a rather high sensitivity with no significant differences between the amorphous and nanocrystalline state. Hydrogen charging was performed electrochemically in a glycerine-phosphoric acid electrolyte. In Zr-Cu-Ni-Al alloys absorption kinetics and storage capacity were found to be very similar for the amorphous and the nanocrystalline phase. In the nanocrystalline alloy consisting mainly of a fcc (big cube) phase with a NiTi2 type structure a hydrogen induced amorphization was observed. Oxidation of metastable Zr-based materials in air was studied below the glass transition temperature at 360°C by thermogravimetry. Oxidation resistance was found to improve very significantly from the amorphous to the nanocrystalline microstructure. The scales formed on both materials consist mainly of columnar ZrO2 with diameter in the nanometer range; Probably including the other metals as a nanocrystalline solid solution.

415 Zr基金属ガラス及びその複合材料のトライボロジー特性(機能材料)

415 Zr基金属ガラス及びその複合材料のトライボロジー特性(機能材料)

The synthesis and properties of Zr-based metallic glasses and glass-matrix composites

In this article, the formation of metallic glass composites in the system Zr/Ti-Al-Cu-Ni by partial devitrification or by blending with second-phase particles through solid-state processing is discussed with respect to the effect of second phases on the thermal stability of the glassy matrix and on mechanical properties. The composites exhibit no significant reduction of the supercooled liquid region as compared to the particle-free metallic glass. The viscosity of the supercooled liquid increases with an increasing volume fraction of particles. The mechanical behavior was characterized by microhardness measurements and constant compression rate tests. At room temperature, there is a significant increase in yield strength with an increasing volume fraction of crystalline phases. At temperatures around the glass transition, the influence of these nanoscaled particles is of minor importance. Rather, the homogeneous flow of the composites is determined by Newtonian viscous flow of the amorphous matrix. This opens a promising route for easy shaping of complex parts of bulk metallic glasses at temperatures that are above Tg.

Physical and Mechanical Properties of Zr-Based Metallic Glasses

Thermal properties, oxidation, hardness, thermal expanstion, electric resistance and Young's modulus were examined for Zr 67 Cu 33 , Zr 65 Al 7.5 Cu 27.5 , Zr 65 Al 7.5 Ni 10 Cu 17.5 and Zr 60 Al 15 Co 2.5 Ni 7.5 Cu 15 amorphous alloys with a wide supercooled liquid region. The results show that (1) Zr 65 Al 17.5 Ni 10 Cu 17.5 and Zr 60 Al 15 Co 2.5 Ni 7.5 Cu 15 alloys are very stable against oxidation up to high temperature of about 650 K, (2) Zr 60 Al 15 Co 2.5 Ni 7.5 Cu 15 alloy is extremely softened in the temperature range of the supercooled liquid region, (3) The thermal expansion coefficient of Zr 60 Al 15 Co 2.5 Ni 7.5 Cu 15 alloy is very small of 0.9 x 10 -5 K -1 , at temperatures below the glass transition temperature (T g ), (4) Temperature coefficient of electric resistance of Zr 60 Al 15 Co 2.5 Ni 7.5 Cu 15 alloy is small of -9 x10 -5 K -1 below about 510 K and (5) Young's modulus increases with increase of alloying components. The temperature dependance of Young's modulus is of the order of as small as ∼10 -5 K -1 except for Zr 67 Cu 33 alloys.