Papers by Keyword: BMG

Abstract: The wetting behavior and the interaction at the liquid-solid interface are significant in preparation of metallic glass composite. In this paper, the wetting behavior and the interfacial interaction between Ti_32.8Zr_30.2Ni_5.3Cu₉Be_22.7 (denoted as ZT3) bulk metallic glass (BMG) alloy melt and Ti6Al4V (denoted as TC4) substrate at different temperatures were investigated using sessile drop method. The results show that ZT3 alloy melt wetted the substrate well. With the increase of temperature, the droplet spread out rapidly and then came to equilibrium gradually. The equilibrium contact angle under 1273 K stabilized at about 15°. Dendrite phase generated at the interface during the wetting progress. The composition of the interface product transformed from Ti_69.8Zr_24.2Al_2.2V₁Cu_2.8 to Ti_73.6Zr_15.3Al₅V_2.7Cu_2.6Ni_0.8 with the temperature rising from 973 K to 1273 K. Meanwhile, the dissolution of the TC4 substrate increased with increasing the temperature.

Abstract: Stiffness and elastic mechanical properties of the Zr44-Ti11-Cu10-Ni10-Be25 metal glass Alloy have been investigated by nanoindentation and Atomic Force Microscopy.Continuous stiffness measurements were carried out on the as received samples. Max indentation depth of 2000 Nm has been chosen. A 3D analysis of the indent traces has been performed using a Atomic Force Microscope: pile-up at the indentation edge was observed. These metallic glasses, therefore, although showing brittle like linear elastic behaviour up to failure are still capable of undergoing plastic shear flow at the nanoscale level that may potentially lead to high material ultimate properties. Elastic modulus of 116,2 ± 0,9 GPa has been found to be independent on indentation depth while a high hardness of 8,0 ± 0,8 GPa has been measured at low indentation depths (100 nm) that progressively reduces to a constant value of 7,0 ± 0,1 GPa at increasing depths (up to 2000 nm).

Abstract: The (Cu42Zr42Al8Ag8)100-xSix amorphous alloy rods, x =0 to 1, with 3 mm in diameter were prepared by Cu-mold drop casting method. The glass forming ability, thermal properties and microstructure evolution was studied by differential scanning calorimetry (DSC), and X-ray diffractometry (XRD). The XRD result reveals that these as-quenched (Cu42Zr42Al8Ag8)100-xSix alloy rods exhibit a broaden diffraction pattern of amorphous phase. The crystallization temperature and GFA (glass forming ability) of (Cu42Zr42Al8Ag8)100-xSix alloys increase with the silicon additions. The highest Trg (0.59) and γ value (0.405) occurred at the (Cu42Zr42Al8Ag8)99.75Si0.25 and (Cu42Zr42Al8Ag8)99.5Si0.5 alloy. In addition, both of the activation energy of crystallization and the incubation time of isothermal annealing for these (Cu42Zr42Al8Ag8)100-xSix alloys indicates that the (Cu42Zr42Al8Ag8)99.25Si0.75 alloy posses the best thermal stability among the (Cu42Zr42Al8Ag8)100-xSix alloy system.

Abstract: Mg-based composites are fabricated through mechanical alloying (MA) the Mg65Cu20Y10Ag5 amorphous alloy spun and mixed with 1-5 vol.% spherical nano-sized ZrO2 particles in the planetary mill, after then formed by hot pressing in Ar atmosphere under different pressures at the temperature 5 K above the glass transition temperature (Tg). The microstructure characterizations of the resulting specimens are conducted by means of XRD, FEG-SEM, and TEM techniques. It is found that the nano-sized ZrO2 dispersed Mg-based composite alloy powders can reach to a homogeneous size distribution (about 80 nm) after 50-hour mechanical alloying. After hot pressing of these composite alloy powders under the pressure of 1100 MPa at 409K, a 96% dense bulk specimen can be formed. Throughout the MA and hot pressing, the amorphous nature of the Mg65Cu25Y10Ag5 matrix is maintained. The hardness of the formed bulk Mg-based composites (with 3 vol.% nano-sized ZrO2 particles) can reach to 370 in Hv scale. In addition, the toughness of the formed bulk Mg-based composites presents an increasing trend with the content of nano-sized ZrO2 particles and can reach to 8.9 MPa m .