The effect of compression on the crystallization behavior and corrosion resistance of Al（86）Ni9La5 amorphous ribbons was investigated by X-ray diffraction （XRD）, transmission electron microscopy （TEM）, scanning elec-tron microscopy （SEM） and electrochemistry test. The XRD and TEM results reveal that the compressed Al（86）Ni9La5 ribbons spun with the circumferential speed （R） of 29.3 m/s are in fully amorphous state; however, the compressed ribbons spun with R=14.7 m/s have crystalline phases embedded in the amorphous matrix. The SEM images indicate that after compression, the toughness of the ribbons increases. Electrochemical results show that the compression decreases the stability of the passive film of the Al（86）Ni9La5 amorphous ribbons, because of the compression-introduced free volume, shear bands and crystalline phases; meanwhile, with R=14.7 m/s, the compression-induced crystalline phases in the Al（86）Ni9La5 ribbons increase the corrosion potential.
The thermal expansion behavior, microhardness and electrochemical corrosion resistance of Au52Cu27Ag17-x（NiZn0.5）x （x=0,6 and 12） alloys were investigated by dilatometer （DIL）, microhardness tester, electrochemical workstation, X-ray diffractometer（XRD）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM） and X-ray photoelectron spectroscopy （XPS）.With increasing x, the relative length expansion and DIL maximum temperature Tl m （i.e., thermal stability） of the alloys increase inthermal expansion measurements, which can be explained by the change of the atomic binding energy, mismatch entropy togetherwith phase transformation. With the increase of x, the microhardness can be improved, but the corrosion resistance decreases; inaddition, the anodic peak current densities of polarization curves decrease, which are related closely with the solid solution degreeand dissolution of Ag, Ni and Zn alloying elements in Cl^- -containing solution.
The effect of casting vacuum on thermodynamic and corrosion properties of Fe61Co7Zr8Mo5W2B17 in shape of cylinder of 3 mm in diameter and ribbon of 20?40μm in thickness and 2?3 mm in width were investigated with X-ray diffraction (XRD), differential scanning calorimetry (DSC), dilatometer (DIL), scanning electron microscopy (SEM) and electrochemical station. It is found that high casting vacuum can improve the glass forming ability (GFA), the contraction degree during heating, and the pitting resistance of the glassy alloy, which can be ascribed to the fact that the dissolution of tungsten in the melt is improved under the high casting vacuum.
The corrosion-induced crystallization of Al94 exNixGd6（x=6 and 10, in at.%） metallic glasses as well as phase separation, oxidation and cracking in good conductivity solution has been investigated by various techniques.The transmission electronic microscopy（TEM） result reveals that crystalline intermetallics and oxides present on the electrochemically thinned hole edge, and the phase separation occurs in the matrix of the as-spun ribbons with the circumferential speed Rcof 29.3 m/s. In addition, the bending and cracking of the samples occur after corrosion. The influence of Ni content on the phase separation, bending and cracking can be explained by the fact that the percolation of the backbone clusters in the amorphous alloy melts and glasses is enhanced by increasing the composition of Ni.
Yonggang WangYan LiuYingjie LiBang AnGuanghui CaoShifeng JinYimin SunWeimin Wang
The corrosion behavior and microstructure of Fe78Si9B13 glassy alloy in NaOH and NaCl solutions under a 0.02-T magnetic field were investigated through electrochemical testing and scanning electron microscopy （SEM）. The current-density prepeak （PP） in the anodic polarization curves in low-concentration NaOH solutions （classified as type I） tends to disappear when the NaOH concentration is increased to 0.4 mol/L and the magnetic field is applied. Under the magnetic field, the height of the second current-density peak is increased in low-concentration NaOH solutions （type I） but decreased in high-concentration NaOH solutions （type Ⅱ）. The non-monotonic effect of the magnetic field was similarly observed in the case of polarization curves of samples measured in NaCl solutions, Ring-like corroded patterns and round pits are easily formed under the magnetic field in NaOH and NaC1 solutions. These experimental results were discussed in terms of the magnetohydrodynamic （MHD） effect.
Hong-di ZhangXiao-yu LiJing PangLi-juan YinHai-jian MaYing-jie LiYan LiuWei-min Wang
The Fe78Si9B13 glassy ribbons were compressed at room temperature with different pressures. The thermal and corrosion behaviors were investigated using various experimental techniques. The X-ray diffraction （XRD） and dilatometer （DIL） results show that the Fe78Si9B13 ribbons are in full amorphous state after pressing and the amount of free volume increases monotonically with increasing pressure. The corrosion resistance of the glassy alloys in various solutions decreases after compression at 10 MPa, but increases after compression at 20 MPa. The non-monotonic change of corrosion resistance is consistent with the result of electrical resistivity, which can be explained by the combining action of free volume that is introduced by the compression and the segregation of Si atoms in the samples.
The crystallization of the （Fe0.78Si0.09B0.13）100-xNix glassy alloys （x=O, 2 and 5） has been investigated by X-ray diffraction （XRD） and differential scanning calorimeter （DSC）. Corrosion resistance analyses have been carried out using electrochemical measurements and corrosion products have been analyzed by scanning electron microscopy （SEM）. The experimental results show that the addition of Ni can promote the nucleation of c^-Fe, retard the decomposition of the metastable borides, and alter the crystallization mode of the present Fe-based glassy alloys. The lattice constant （ao^e） of c^-Fe in the annealed samples shows a decreasing trend with increasing annealing time. The Ni addition can improve the corrosion resistance of the as-quenched Fe-based glassy alloys in H2S04, NaCI and NaOH solutions. The results indicate that Ni can promote the diffusion of Si atoms during quenching and annealing processes.
