The high temperature deformation behaviors and thermal workability of Cu_（43）Zr_（48）Al_9 and（Cu_（43）Zr_（48）Al_9）_（98）Y_2 bulk metallic glasses in the supercooled liquid region were investigated by the unia...The high temperature deformation behaviors and thermal workability of Cu_（43）Zr_（48）Al_9 and（Cu_（43）Zr_（48）Al_9）_（98）Y_2 bulk metallic glasses in the supercooled liquid region were investigated by the uniaxial compression tests. The results showed that the high temperature deformation behaviors were highly sensitive to strain rate and temperature, and the flow stress decreased with the increase of temperature, as well as with the decrease of strain rate. Additionally, the（Cu_（43）Zr_（48）Al_9）_（98）Y_2 bulk metallic glass displayed smaller flow stress under the same condition. The flow behavior changed from Newtonian to non-Newtonian with increase of the strain rate, as well as the decrease of temperature, which could be explained by the transition state theory. We found that（Cu_（43）Zr_（48）Al_9）_（98）Y_2 bulk metallic glass had better flow behavior than the Cu_（43）Zr_（48）Al_9 bulk metallic glass in the supercooled liquid region. In addition, the processing maps of the two bulk metallic glasses were constructed considering the power dissipation efficiency. The optimum domain for thermal workability of the bulk metallic glass was located using the processing map, where the power dissipation efficiency was larger than 0.8. It was shown that the（Cu_（43）Zr_（48）Al_9）_（98）Y_2 bulk metallic glass, which had larger area of optimum domain, had excellent thermoplastic forming.展开更多
The FePC-based bulk metallic glasses（BMGs）have been demonstrated to possess high plasticity and good soft magnetic properties.However,the relatively poor glass forming ability（GFA）and thermal stabilities limited t...The FePC-based bulk metallic glasses（BMGs）have been demonstrated to possess high plasticity and good soft magnetic properties.However,the relatively poor glass forming ability（GFA）and thermal stabilities limited their application in industries.The effects of microalloying with B in FePC-based BMGs on the GFA and thermal behaviors were systematically investigated.It was found that a small amount of B addition can dramatically enhance the GFA of FePC-based BMGs,which in turn leads to the critical maximum diameter up to 2 mm for full glass formation even using low cost raw materials.The underlying mechanism of the enhancement of GFA from the competing crystalline phase with amorphous phase,the average thermal expansion coefficient and dynamic viscosity were discussed in detail.展开更多
The effect of adding Ta on the changes of microstructure and Ms temperature of a dualphase shape memory alloy with compositions of (Ni51 Ti49)1 -x.Tax. and Ni50-Ti50 -g.Ta.g were systematically studied. An optical mi...The effect of adding Ta on the changes of microstructure and Ms temperature of a dualphase shape memory alloy with compositions of (Ni51 Ti49)1 -x.Tax. and Ni50-Ti50 -g.Ta.g were systematically studied. An optical microscope, SEM, X-ray diffraction and DSC were utilized in this work. The evolution of the microstructure as a function of Ta content was characterized. The variation of the Ni/Ti ratio in the NiTi phase plays an important role in the change of the Ms temperatures due to the addition of Ta. A pseudobinary NiTi-Ta phase diagram was proposed based on these results.展开更多
基金supported by the Education Department of Shaanxi Province(14JK1351)the Principal Fund of Xi’an Technological University(0852-302021407)
文摘The high temperature deformation behaviors and thermal workability of Cu_（43）Zr_（48）Al_9 and（Cu_（43）Zr_（48）Al_9）_（98）Y_2 bulk metallic glasses in the supercooled liquid region were investigated by the uniaxial compression tests. The results showed that the high temperature deformation behaviors were highly sensitive to strain rate and temperature, and the flow stress decreased with the increase of temperature, as well as with the decrease of strain rate. Additionally, the（Cu_（43）Zr_（48）Al_9）_（98）Y_2 bulk metallic glass displayed smaller flow stress under the same condition. The flow behavior changed from Newtonian to non-Newtonian with increase of the strain rate, as well as the decrease of temperature, which could be explained by the transition state theory. We found that（Cu_（43）Zr_（48）Al_9）_（98）Y_2 bulk metallic glass had better flow behavior than the Cu_（43）Zr_（48）Al_9 bulk metallic glass in the supercooled liquid region. In addition, the processing maps of the two bulk metallic glasses were constructed considering the power dissipation efficiency. The optimum domain for thermal workability of the bulk metallic glass was located using the processing map, where the power dissipation efficiency was larger than 0.8. It was shown that the（Cu_（43）Zr_（48）Al_9）_（98）Y_2 bulk metallic glass, which had larger area of optimum domain, had excellent thermoplastic forming.
基金financially supported by the National Natural Science Foundation of China(Nos.51301142and 51671162)China Postdoctoral Science Foundation(Nos.2015T80957and 2014M562279)+1 种基金Chongqing Research Program of Basic Research and Frontier Technology(No.cstc2015jcyjBX0107)the Fundamental Research Funds for the Central Universities(Nos.XDJK2015C064and XDJK2015C003)
文摘The FePC-based bulk metallic glasses（BMGs）have been demonstrated to possess high plasticity and good soft magnetic properties.However,the relatively poor glass forming ability（GFA）and thermal stabilities limited their application in industries.The effects of microalloying with B in FePC-based BMGs on the GFA and thermal behaviors were systematically investigated.It was found that a small amount of B addition can dramatically enhance the GFA of FePC-based BMGs,which in turn leads to the critical maximum diameter up to 2 mm for full glass formation even using low cost raw materials.The underlying mechanism of the enhancement of GFA from the competing crystalline phase with amorphous phase,the average thermal expansion coefficient and dynamic viscosity were discussed in detail.
文摘The effect of adding Ta on the changes of microstructure and Ms temperature of a dualphase shape memory alloy with compositions of (Ni51 Ti49)1 -x.Tax. and Ni50-Ti50 -g.Ta.g were systematically studied. An optical microscope, SEM, X-ray diffraction and DSC were utilized in this work. The evolution of the microstructure as a function of Ta content was characterized. The variation of the Ni/Ti ratio in the NiTi phase plays an important role in the change of the Ms temperatures due to the addition of Ta. A pseudobinary NiTi-Ta phase diagram was proposed based on these results.
