The viscosity of bulk metallic glass(BMG) Zr41Ti14Cu12.5Ni10Be22.5(Vit1) around glass transition was derived from the static extension method. In addition, the diffusion coefficient of the medium size atom Fe in the B...The viscosity of bulk metallic glass(BMG) Zr41Ti14Cu12.5Ni10Be22.5(Vit1) around glass transition was derived from the static extension method. In addition, the diffusion coefficient of the medium size atom Fe in the BMG Vit1 was calculated by using the Stokes-Einstein relation. The temperature dependence of both viscosity and diffusion coefficient of the atom Fe, could also be well fitted by two different Arrhenius equations at temperatures below and above the glass transition temperature. In the glass state, the effects of heating rate on viscosity and diffusivity were significant due to the structure relaxation. Besides, it was indicated that the linear plots between lnD0 and ED for above and below glass transition are just the same. The results suggest that the intrinsic diffusion of medium size atoms in BMGs, above and below glass transition, is possibly collective hopping processes.展开更多
The crystallization kinetics of Zr 41 Ti 14 Cu 12.5 Ni 10 Be 22.5 bulk metallic glass has been studied by using DSC and XRD. The results show that two exothermal peaks are observed when the alloy is heated to 500?℃, ...The crystallization kinetics of Zr 41 Ti 14 Cu 12.5 Ni 10 Be 22.5 bulk metallic glass has been studied by using DSC and XRD. The results show that two exothermal peaks are observed when the alloy is heated to 500?℃, one peak results dominantly from the formation of Ti 2Ni ( α phase transition), the other peak is mainly due to the formation of Zr 2Cu ( β phase transition). At the beginning of the crystallization, the activation energy of the α phase is smaller, and it increases with increasing crystallized fraction ( x c). When x c increases to 90%, the crystallization activation energy shows the largest value (220?kJ/mol). The crystallization activation energy of the β phase remains about 227?kJ/mol, as it’s crystallized fraction is below 60%, and then it increases with increasing crystallized fraction, and shows the largest activation energy of 257?kJ/mol, as the x c is 65%.展开更多
Zr41Ti14Cu12.5Ni10Be22.5 bulk metallic glass (BMG) is annealed at 573 K under 3 GPa and its structural relaxation is investigated by X-ray diffraction, ultrasonic study, compression as well as sliding wear measurement...Zr41Ti14Cu12.5Ni10Be22.5 bulk metallic glass (BMG) is annealed at 573 K under 3 GPa and its structural relaxation is investigated by X-ray diffraction, ultrasonic study, compression as well as sliding wear measurements. It is found that after the ZrTiCuNiBe BMG sample was annealed under high pressure, the mechanical properties were improved. Moreover, the BMG with relaxed structure exhibits markedly different acoustic properties. These results are attributed to the fact that relaxation under high-pressure results in a microstructural transformation in the BMG.展开更多
Mechanical properties of the Zr41Ti14Cu12.5Ni10Be22.5 bulk amorphous alloy at different temperatures were investigated. The compression test was carried out on a Gleebe-3200 machine at 345 and 375°C, respectively...Mechanical properties of the Zr41Ti14Cu12.5Ni10Be22.5 bulk amorphous alloy at different temperatures were investigated. The compression test was carried out on a Gleebe-3200 machine at 345 and 375°C, respectively, in the supercooled liquid region. It is shown that decreasing the compressive rate and increasing temperature have a similar influence trend on the compressive behavior of the bulk amorphous alloy. Room and low temperature tensile strengths were tested on the Instron materials testing system. At low temperature, the tensile strength decreased with decreasing of the testing temperature. Hardness measurement indicated that below the glass transition temperature, the hardness decreased with increasing of the annealing temperature and duration time. It, however, increased when the annealing treatment was performed above the glass transition temperature.展开更多
文摘The viscosity of bulk metallic glass(BMG) Zr41Ti14Cu12.5Ni10Be22.5(Vit1) around glass transition was derived from the static extension method. In addition, the diffusion coefficient of the medium size atom Fe in the BMG Vit1 was calculated by using the Stokes-Einstein relation. The temperature dependence of both viscosity and diffusion coefficient of the atom Fe, could also be well fitted by two different Arrhenius equations at temperatures below and above the glass transition temperature. In the glass state, the effects of heating rate on viscosity and diffusivity were significant due to the structure relaxation. Besides, it was indicated that the linear plots between lnD0 and ED for above and below glass transition are just the same. The results suggest that the intrinsic diffusion of medium size atoms in BMGs, above and below glass transition, is possibly collective hopping processes.
文摘The crystallization kinetics of Zr 41 Ti 14 Cu 12.5 Ni 10 Be 22.5 bulk metallic glass has been studied by using DSC and XRD. The results show that two exothermal peaks are observed when the alloy is heated to 500?℃, one peak results dominantly from the formation of Ti 2Ni ( α phase transition), the other peak is mainly due to the formation of Zr 2Cu ( β phase transition). At the beginning of the crystallization, the activation energy of the α phase is smaller, and it increases with increasing crystallized fraction ( x c). When x c increases to 90%, the crystallization activation energy shows the largest value (220?kJ/mol). The crystallization activation energy of the β phase remains about 227?kJ/mol, as it’s crystallized fraction is below 60%, and then it increases with increasing crystallized fraction, and shows the largest activation energy of 257?kJ/mol, as the x c is 65%.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.50171059 and 50171077)
文摘Zr41Ti14Cu12.5Ni10Be22.5 bulk metallic glass (BMG) is annealed at 573 K under 3 GPa and its structural relaxation is investigated by X-ray diffraction, ultrasonic study, compression as well as sliding wear measurements. It is found that after the ZrTiCuNiBe BMG sample was annealed under high pressure, the mechanical properties were improved. Moreover, the BMG with relaxed structure exhibits markedly different acoustic properties. These results are attributed to the fact that relaxation under high-pressure results in a microstructural transformation in the BMG.
基金This work was supported by the National Natural Science Foundation of China(Grant No.50325 103)Hebei Provincial Natural Science Fundation(Grant No.E2004000209/503278)Hebei Education Department Program(Grant No.2004464).
文摘Mechanical properties of the Zr41Ti14Cu12.5Ni10Be22.5 bulk amorphous alloy at different temperatures were investigated. The compression test was carried out on a Gleebe-3200 machine at 345 and 375°C, respectively, in the supercooled liquid region. It is shown that decreasing the compressive rate and increasing temperature have a similar influence trend on the compressive behavior of the bulk amorphous alloy. Room and low temperature tensile strengths were tested on the Instron materials testing system. At low temperature, the tensile strength decreased with decreasing of the testing temperature. Hardness measurement indicated that below the glass transition temperature, the hardness decreased with increasing of the annealing temperature and duration time. It, however, increased when the annealing treatment was performed above the glass transition temperature.
