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.     

Effect of Nb addition on the subsurface deformation behavior in Cu47Ti34Zr11Ni8 bulk metallic glasses through Vickers indentation

In this paper, 3 mm diameter (Cu₄₇Ti₃₄Zr₁₁Ni₈)_100−xNb_x (x = 0,1,2) glass forming alloys were fabricated by water-cooled copper mould cast. Microstructural characterization reveals that the monolithic Cu₄₇Ti₃₄Zr₁₁Ni₈ bulk metallic glass exhibits homogenous amorphous structure. While the alloys with Nb addition exhibit a composite structure. For alloys with x = 1, micro-scaled crystalline particles were found to distribute in the glassy matrix. For alloys with x = 2, the microstructure is dominated by a high density of dendritic phase embedded in the glassy matrix. Bonded interface technique was adopted to study the deformation behavior of the alloys underneath the Vickers indentation. It reveals that the subsurface shear patterns are significantly affected by the precipitated phases. The different deformation mechanism of the alloys resulted from the minor Nb addition was put forward and discussed.     

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.     

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.     

Preparation and crystallization of Ti53Cu27Ni12Zr3Al7Si3B1 bulk metallic glass with wide supercooled liquid region

Ti-based bulk metallic glass (BMG) alloy with the composition of Ti₅₃Cu₂₇Ni₁₂Zr₃Al₇Si₃B₁ was prepared by copper molder casting method and ribbon sample was prepared by melt spinning to compare. The thermal instability of this glass phase was examined by using differential scanning calorimetry (DSC) and differential thermal analysis (DTA). The results revealed that the supercooled liquid region (ΔT_x), glass transition temperature (T_g) and reduced glass transition temperature (T_g/T_m) of the glassy alloy are detected to be 69, 685 and 0.62 K, respectively. The crystallization behavior of the Ti-based glass phase was also investigated by annealing the glass phase at series temperatures above T_g. The annealed microstructures were examined by means of X-ray diffraction experiments. The crystallization process of the BMG can be characterized by metastable crystalline phases at the first crystallization step and further transition to stable crystalline phases at high temperature through metastable crystalline phase.