Papers by Keyword: Cu-Based Bulk Metallic Glass

Abstract: The glassy alloy rods of Cu₅₀Zr₄₃Al₇, (Cu₅₀Zr₄₃Al₇)_100-xY_x(x=2,5) and (Cu₅₀Zr₄₃Al₇)_100-xAg_x(x=6,7) with diameters of 3.0 mm were prepared by copper mold suction casting method. The influence of adding Ag and Y to Cu₅₀Zr₄₃Al₇ metallic glass on glass formation ability (GFA) and thermal stability was studied by means of X-ray diffraction analysis (XRD) and differential scanning calorimetry (DSC). The results show that Ag and Y appropriate micro-addition enhance the glass formation ability and thermal stability of the Cu-Zr-Al metallic glass. The effect of Ag is better than that of Y. The addition of Ag causes a increase of the reduced glass transition temperature (T_rg) of (Cu₅₀Zr₄₃Al₇)_100-xAg_x alloy from 0.618 at 0 at.% Ag to 0.628 at 7 at.% Ag. The width of the supercooled liquid region of Cu₄₃Zr₄₃Al₇Ag₇ glassy alloy increases about 25K compared with that of Cu₅₀Zr₄₃Al₇, and the γ value of Cu₄₃Zr₄₃Al₇Ag₇ reaches 0.433. The electrochemical corrosion behaviors of Cu₅₀Zr₄₃Al₇, (Cu₅₀Zr₄₃Al₇)_100-xY_x(x=2,5) and (Cu₅₀Zr₄₃Al₇)_100-xAg_x(x=6,7) metallic glasses in 3.5% NaCl solution were investigated by potentiodynamic polarization method. It is found that corrosion resistance of all amorphous alloys is better than that of the corresponding crystalline alloys. The Ag and Y micro-addition improve corrosion resistance of Cu₅₀Zr₄₃Al₇ metallic glass. The corrosion current density of Cu₄₃Zr₄₃Al₇Ag₇ metallic glass decreases 1~2 orders of magnitude compared with that of Cu₅₀Zr₄₃Al₇.

Abstract: Cu-based bulk metallic glasses (BMGs) with 5 mm in diameter were synthesized by copper mold casting. The effects of tin (Sn) addition on glass-forming ability (GFA), thermal stability of BMGs were investigated. It was found the addition of 4 at. % Sn is effective for an increase in GFA. The crystallization behaviors of Cu-based bulk metallic glasses during continuous heating are investigated mainly by differential scanning calorimeter(DSC).The results show that the characteristic temperatures(Tg,Tx and Tp) shifted to high temperature region with increasing of heating rates. The activation energies Eg, Ex and Ep, corresponding to characteristic temperatures Tg, Tx, and Tp, respectively, were obtained from Kissinger and Ozawa equations. The calculated activation energies agree well with Kissinger or Ozawa equations due to the almost invariability of the crystallization volume fraction at the characteristic temperatures for different heating rates.

Abstract: To synthesize a crystalline-glass composite in a Cu-based bulk metallic glass, the monotectic reaction was used. The (Zr-Sn-Pb)-rich crystalline phase was found to coexist with the (Cu-Ti-Ni)-rich glassy phase during the process of quenching from the melt in the (Cu47Ti33Zr11Ni6Sn2Si1)100-x+Pbx=1,2 system. Microstructures consisting of uniformly dispersed crystalline particles in the amorphous matrix were observed by scanning electron microscope (SEM) and transmission electron microscope (TEM). Compressive tests demonstrated that the fracture strain of the sample with a Pb content of 1 at% was three times higher than that of the sample with no Pb.