Study of mechanical deformation of Zr55Cu30Al10Ni5 bulk metallic glass through instrumented indentation

Instrumented sharp indentation experiments using both conical and Vickers diamond pyramidal indenters were carried out to study deformation characteristics of Zr₅₅Cu₃₀Al₁₀Ni₅ bulk metallic glass. Finite element simulations of instrumented indentation were also performed to formulate an overall constitutive response. Comparing the experimentally obtained results with the finite element predictions, it can be stated that mechanical deformation of the bulk metallic glass can be described well by both Mohr-Coulomb and Drucker-Prager constitutive criteria. Using these criteria, the extent of material pile-up observed around the indenter was also estimated very well.     

First investigations on twin-rolled Zr59Cu20Al10Ni8Ti3 bulk amorphous alloy by mechanical spectroscopy

Zr₅₉Cu₂₀Al₁₀Ni₈Ti₃ is one among compositions of ZrCu-based alloys giving bulk amorphous material by cooling from the melt. Twin-roll casting enabling samples suitable for our inverted torsion pendulum has been processed in strips of about 0.60 mm thick.

Low temperature IF measurements have been conducted on a specimen from room temperature to −120 °C at different heating and cooling rates. IF spectra exhibit peaks at around −40 °C (cooling) and −10 °C (heating) which are sensitive to heating rates and to the number of cycle (heating and cooling). DSC measurements have also been performed to help interpret the phenomena linked to the IF peaks.     

Precipitation of icosahedral quasicrystalline phase in metallic Zr65Al7.5Ni5Cu17.5Re5 glass

Recently, the precipitation of an icosahedral quasicrystalline phase (I-phase) in metallic Zr₆₅Al_7.5Ni₁₀Cu_12.5M₅ (M=Pd, Pt, Au and Ag) glasses, which were obtained by adding noble metals to the well-known metallic Zr₆₅Al_7.5Ni₁₀Cu_17.5 glass, was reported. In the present work, the crystallization process of a metallic Zr₆₅Al_7.5Ni₅Cu_17.5Re₅ glass, which was obtained by adding non-noble metal Re to Zr₆₅Al_7.5Ni₁₀Cu_17.5, was studied. Two exothermic peaks were observed in the differential scanning calorimetry curve of the metallic glass, of which the low temperature one corresponds to the precipitation of an I-phase. The present result demonstrates that the addition of Re is effective in promoting the precipitation of I-phase, in addition to the previously reported noble metals (Pd, Pt, Au and Ag). The atomic radii of these elements are limited to the range of 0.137 to 0.144 nm, implying that atomic size is a significant factor.     

Devitrification behavior and mechanical property of Cu54Ni6Zr22Ti18 glass powders

Cu₅₄Ni₆Zr₂₂Ti₁₈ amorphous materials were prepared using gas atomization, followed by spark plasma sintering (SPS). The crystallization behavior and mechanical properties were studied using X-ray diffractometer (XRD), differential scanning calorimeter (DSC) and transmission electron microscope (TEM). With annealing the gas atomized powders to the temperatures of 837 K and 909 K, fine particles such as Cu₁₀Zr₇ and Cu₅₁Zr₁₄ were precipitated and embedded in the amorphous matrix, respectively. Each size of precipitates at 909 K is about 50 nm and 20 nm, respectively. Microstructural variation and mechanical properties were investigated as a function of the initial powder size and spark plasma sintering (SPS) pressure.     

Compressive fracture of Zr55Al10Ni5Cu30 bulk amorphous alloy at high temperatures

The fracture behavior of the Zr₅₅Al₁₀Ni₅Cu₃₀ bulk amorphous alloy under uniaxial compression at high temperatures has been investigated. At room temperature, the fracture occurred along the maximum shear plane which declined by 45° to the direction of the applied load, and a crack with serrated edge appeared on the ridge of the veins at the fracture surface for the Zr₅₅Al₁₀Ni₅Cu₃₀ bulk amorphous alloy. At high temperatures, the compressive fracture surface of the Zr₅₅Al₁₀Ni₅Cu₃₀ bulk amorphous alloy became much rougher than that at room temperature and steps appeared on the fracture surface. With increasing temperature, a different pattern from the vein-like morphology appeared on the fracture surface, which is very similar to the lava-flow. This type of fracture pattern is most likely due to the adiabatic heating created by plastic flow.     

Laser cladding of Zr65Al7.5Ni10Cu17.5 amorphous alloy on magnesium

Laser cladding of amorphous alloy Zr₆₅Al_7.5Ni₁₀Cu_17.5 on magnesium substrate was conducted using the blown powder method. The thickness of the coating was about 1.5 mm. The resulting microstructure, wear resistance and corrosion resistance of the coating were studied. The results of the XRD and TEM analyses showed that up to a depth of 1.1 mm, the coating had an amorphous structure, and no apparent crystalline structures were found. The coated specimen exhibited wear and corrosion resistance superior to that of the uncoated specimen: the wear loss was significantly reduced, some thirteen-fold; and the corrosion current was lowered by three orders of magnitude.     

Zr55Al10Ni5Cu30非晶合金晶化相转变的价电子结构分析

基于EET理论,计算了F-Zr₂(Ni,Cu)和tI-Zr₂Cu及tI-Zr₂(Cu,Ni)相的价电子结构,用最强键键合力n₁、结构单元总成键能力F和单位成键能力F_v分析了F-Zr₂Ni亚稳相向tI-Zr₂Cu型稳定相的转变过程。研究发现:F-Zr₂Ni的n^{F-Zr₂Ni₁值比tI-Zr₂Cu的ntI-Zr₂Cu₁值大115.36%,FF-Zr₂Ni_v值比tI-Zr₂Cu的FtI-Zr₂Cu_v值大34.03%;F-Zr₂(Ni0.3,Cu0.7)的nF-Zr₂(Ni0.3,Cu0.7)₁值比tI-Zr₂Cu的ntI-Zr₂Cu₁值大0.36%,FF-Zr₂(Ni0.3,Cu0.7)_v值比tI-Zr₂Cu的FF-Zr₂Ni}_v值大1.25%; tI-Zr₂(Cu0.6,Ni0.4)的n^{tI-Zr₂(Cu0.6,Ni0.4)₁值比F-Zr₂(Ni0.3,Cu0.7)的nF-Zr₂(Ni0.3,Cu0.7)}₁值大12.95%, F^{tI-Zr₂(Cu0.6,Ni0.4)_v值比F-Zr₂(Ni0.3,Cu0.7)的FF-Zr₂(Ni0.3,Cu0.7)}_v值大14.41%; 从价电子结构角度看,F-Zr₂Ni不能直接转变为tI-Zr₂Cu,F-Zr₂(Ni,Cu)不易分解重构为tI-Zr₂Cu;F-Zr₂(Ni0.3,Cu0.7)可分解并转变为tI-Zr₂(Cu0.6,Ni0.4)。     

Vickers indentation tests in a Zr62.55Cu17.55Ni9.9Al10 bulk amorphous alloy

Vickers indentation tests were conducted on a Zr_62.55Cu_17.55Ni_9.9Al₁₀ bulk amorphous alloy to investigate the evolution of shear bands and its plastic deformation dimension via a bonded interface technique. Under all indentation loads, the plastic deformation is accommodated through semi-circular and radial shear bands. The plastic deformation dimension increases with increasing the indentation loads. A simplified λ = C(P)^0.5 model was put forward to predict and estimate the plastic deformation dimension characterized by shear bands in the subsurface. For the Zr_62.55Cu_17.55Ni_9.9Al₁₀ amorphous alloy, C is about 15.314 µm/N^0.5. The normalized shear band zone is independent to the indentation load.     

Wettability and reactivity between B4C and molten Zr55Cu30Al10Ni5 metallic glass alloy

The isothermal wetting and spreading behaviors of molten Zr₅₅Cu₃₀Al₁₀Ni₅ metallic glass alloy on B₄C substrates were studied using a modified sessile drop method at 1133–1253 K in a high vacuum. A distinct reaction layer consisting of ZrB₂ and ZrC_x was produced at the interface and displayed good wettability with the molten alloy. The entire spreading kinetics could be characterized by four representative stages: (i) an initial rapid spreading presumably driven by adsorption of the active Zr atoms at the solid–liquid interface, (ii) a quasi-linear and (iii) a linear spreading stage controlled by the chemical reaction between Zr and B₄C in both cases, and (iv) an approach-to-equilibrium stage with precipitation of crystals in the liquid. An increase in temperature promotes the wetting and reaction. In view of the reasonable wettability and reactivity, there is a potential for preparing Zr-base bulk metallic glass matrix composites reinforced by in situ ZrC–ZrB₂ hybrid ceramic particulates using B₄C as a reaction agent by way of an infiltration synthesis technique.     

Effect of quenching mode on the mechanical properties of a Zr64Al10Ni15Cu11 metallic glass

This paper studied the effect of quenching mode on the mechanical properties of a Zr₆₄Al₁₀Ni₁₅Cu₁₁ metallic glass. It has been shown that the specimen through annealing and water quenching treatments has a higher strength of 1698 MPa than the specimen without annealing treatment (with a strength of 1572 MPa) due to the presence of nanocrystals in the amorphous matrix, which act as obstacles to the shear bands movement during deformation and thus improve the strength. It has also been shown that the specimen through annealing and air quenching treatments has a lower strength of 1119 MPa than the specimen without annealing treatment (with a strength of 1572 MPa) due to the heterogeneous distribution of the internal stress, which induces the crack initiations and catastrophic failure at a rather low external applied stress.     

Nanoscale amorphous “band-like” structure induced by friction stir processing in Zr55Cu30Al10Ni5 bulk metallic glass

Friction stir processing (FSP) is successfully applied in Zr-based bulk metallic glass in this study. In the FSP specimen obtained, large defects and cracks are not present in the FSP region. The microstructure in the friction zone (FZ) exhibited an amorphous “band-like” structure with widths of 10-45 nm and a small number of nanoscale crystalline particles were observed along the “band-like” structure. We concluded that the nanoscale amorphous “band-like” structure obtained in this study is nanoscale shear bands. From this result, FSP is expected to be a useful method of processing bulk metallic glass with nanoscale shear bands to investigate the influence of shear bands on the deformation behavior of bulk metallic glass.     

Corrosion behavior of Zr41.2Ti13.8Ni10Cu12.5Be22.5 bulk metallic glass in various aqueous solutions

In this study electrochemical corrosion behavior of Zr_41.2Ti_13.8Ni₁₀Cu_12.5Be_22.5 bulk metallic glass (BMG) in various aqueous solutions (3.5% NaCl, 1 N HNO₃, H₂SO₄ and HCl) in order to compare with 316L stainless steel were thoroughly investigated. Scanning electron microscopy (SEM) was used to evaluate the influence of corrosion on the surface topography in immersion specimens to examine where the corrosion pits initiated. Corrosion rate of Zr_41.2Ti_13.8Ni₁₀Cu_12.5Be_22.5 BMG in 3.5% NaCl solution was ∼0.6 mpy and its excellent corrosion resistance can be concluded. Polarization and SEM results also vouched a remarkable corrosion resistance of Zr_41.2Ti_13.8Ni₁₀Cu_12.5Be_22.5 BMG in 3.5% NaCl aqueous solution in comparison with 316L stainless steel.     

Zr46Cu46Al7Gd1块体非晶合金氧化过程的光学表征

相比于晶态合金,非晶合金表现出显著不同的氧化行为,其氧化过程受无序原子结构和非平衡状态的影响.为揭示非晶合金的早期氧化过程,需要对其氧化行为进行快速表征.本文以Zr₄₆Cu₄₆Al₇Gd₁块体非晶合金为对象,通过测量光学常数的变化对氧化行为进行表征.与X射线衍射、扫描电子显微镜和热重分析测得的结果相比,光学常数不仅可以反映非晶合金发生明显氧化的起始温度,还可以反映难以用传统方法表征的早期氧化过程.本研究结果说明光学常数是反映氧化行为的灵敏参数,将有助于认识非晶合金氧化过程随温度、时间和组分变化的演化过程.     

Microstructure and Wear Behavior of FeBSiNbCr Metallic Glass Coatings

In this paper,FeBSiNbCr metallic glass coatings were prepared onto AISI 1045 steel substrate by using wire arc spraying process.The phase and structure of the coating were characterized by transmission electron microscopy(TEM),X-ray diffraction(XRD)and scanning election microscopy(SEM)equipped with energy dispersive X-ray analysis(EDX).The microstructure of the coating consists of full amorphous phase.The coating has high hardness and low porosity.Full density and little oxides are detected in the coating.T...     

Crystallization Behavior of Zr_(55)Al_(10)Cu_(30)Ni_5 Bulk Metallic Glass Rolled at Room Temperature

Zr 55 Al 10 Cu 30 Ni 5 bulk metallic glass was rolled up to 95% in thickness reduction at room temperature, and the dependences of microstructure and thermal stability on the strain were investigated. It is revealed that phase transformations do not occur during the rolling, but the split of the crystallization peaks becomes more and more obvious with increasing thickness reduction. Analyses of the radial distribution functions and the pair correlation functions indicate that the rolling has enhanced the sh...     

Cooling rate effects on the microstructure and phase formation in Zr51Cu20.7Ni12Al16.3 bulk metallic glass

A detailed transmission electron microscope (TEM) study has been conducted to investigate the microstructures of the Zr₅₁Cu_20.7Ni₁₂Al_16.3 metallic glass formed at different cooling rates. It has been found that the most competitive crystalline phase to the amorphous structure is an oxygen-stabilized FCC NiZr₂-type phase, which in turn acts as the leading phase to trigger the formation of other crystalline phases in the slow-cooled alloy.     

Cooling rate induced variation in microstructure and magnetic structure of Nd60Fe30Al10 glass forming alloy

Cooling rate induced variation in microstructure and magnetic structure was investigated in the as-cast Nd₆₀Fe₃₀Al₁₀ alloy. Because the cooling rate was different from the periphery to the center regions, apparent evolution from a full amorphous to a partial precipitated crystalline structure was observed in one as-cast sample. Corresponding to different microstructures, two magnetic domain structures, i.e. fine strip-like domains in sub-micron scale and sunflower-like domains in micron scale, were observed at the periphery and the center of a cross section, respectively. The variation of magnetic properties was discussed in the view of exchange interaction coupling.     

Influence of quenching rate on the crystallization behaviors of Mg63Ni22Pr15 metallic glass

The influence of the quenching rate (from 5 m/s to 40 m/s) on the crystallization behaviors of melt-spun Mg₆₃Ni₂₂Pr₁₅ metallic glasses has been studied. The isochronal differential scanning calorimeter (DSC) measurement at 20 K/min shows that the transition temperatures increase with the quenching rate, while the parameters of the glass-forming ability keep constant. The kinetics of isothermal crystallization performed at 481 K within the supercooled liquid region is discussed with some nucleation and growth models. The fittings show that with decreasing quenching rate, the quenched-in nucleation becomes more important and even dominant in the crystallization process.     

Formation of reactive layers in brazed Ti and Cu using a melt-spun Zr41.2Ti13.8Ni10.0Cu12.5Be22.5 alloy

Investigations on the microstructure of brazed Ti and Cu when using a Zr_41.2Ti_13.8Ni_10.0Cu_12.5Be_22.5 alloy revealed that mainly Ti-rich compounds were formed at the brazed joint after brazing at 790 °C for 10 min. However, detailed microstructural investigations revealed that the interfacial areas close to the Cu consisted of orthorhombic Cu₄Ti, orthorhombic Cu₃Ti, hexagonal Cu₂TiZr and tetragonal CuTi compounds. The formation of a Cu₂TiZr Laves phase at the interfacial areas close to the Cu possibly suppresses a diffusion of Cu into the central areas of the brazed joint due to its characteristics of a high solubility and high melting temperature.