A thermodynamic study has been carried out on M-Si-B (M=Fe, Ni) ternary systems. A regular solution approximation based on the sublattice model was adopted to describe the Gibbs energy for the individual phases in the...A thermodynamic study has been carried out on M-Si-B (M=Fe, Ni) ternary systems. A regular solution approximation based on the sublattice model was adopted to describe the Gibbs energy for the individual phases in the binary and ternary systems. Thermodynamic parameters for each phase were evaluated by using the experimental data. These parameters enabled us to obtain reproducible calculations of the isothermal and vertical section diagrams. The amorphous-forming ability of M-Si-B ternary alloys has been evaluated by introducing thermodynamic quantities obtained from the phase diagram calculations into Davies-Uhlmann kinetic formulations. For the computation, the time-temperature- transformation (TTT) diagram, which gives the time necessary for the formation of the detectable amount of crystal during transformation, was obtained at a finite temperature. The critical cooling rate for amorphization could be defined as the minimum cooling speed that does not intersect the TTT curve and, hence, these critical cooling rates enable us to evaluate the glass-forming ability of M-Si-B ternary alloys. The driving force for the crystallization of the crystalline phase was derived, on the basis of the thermodynamic functions of each phase formulated by the present study. The calculated results showed good agreement with the experimental data on the compositional range of amorphization in these alloy systems.展开更多
采用单辊快速凝固法制备出Mg80 x Alx Cu15Y5(x=0,1)合金薄带,再将薄带在不同温度下进行退火处理,利用XRD、DSC和HRTEM分析Al元素对Mg80 x Alx Cu15Y5(x=0,1)合金薄带的非晶形成能力及热稳定性的影响。结果表明:Al的加入使得Mg-Cu-Y合...采用单辊快速凝固法制备出Mg80 x Alx Cu15Y5(x=0,1)合金薄带,再将薄带在不同温度下进行退火处理,利用XRD、DSC和HRTEM分析Al元素对Mg80 x Alx Cu15Y5(x=0,1)合金薄带的非晶形成能力及热稳定性的影响。结果表明:Al的加入使得Mg-Cu-Y合金的玻璃转变温度和初始结晶温度升高,过冷液相区宽度ΔTx因Al部分置换Mg而增大,约化玻璃转变温度Trg从0.616升至0.631,合金的非晶形成能力及热稳定性提高。随着退火温度的升高,Mg79Al1Cu15Y5合金的晶化率低于Mg80Cu15Y5合金的。当退火温度为523 K时Mg80 x Alx Cu15Y5(x=0,1)合金均发生明显晶化,在非晶基体上弥散析出大量HCP-Mg和Mg2Cu纳米颗粒;当温度升高至573 K时,Mg79Al1Cu15Y5合金中有针状AlMg化合物相形成。展开更多
为了分析Al-Y-Fe三元合金的玻璃形成能力和热稳定性,采用熔体急冷法制备了Al(100-2x)YxFex(其中x=3,4,5,6,7,8,9)、Al89Y5Fe6、Al88Y5Fe7和Al87Y5Fe8合金条带.利用x-射线衍射(XRD)及透射电子显微镜(TEM)表征了急冷态和部分晶化后条带的...为了分析Al-Y-Fe三元合金的玻璃形成能力和热稳定性,采用熔体急冷法制备了Al(100-2x)YxFex(其中x=3,4,5,6,7,8,9)、Al89Y5Fe6、Al88Y5Fe7和Al87Y5Fe8合金条带.利用x-射线衍射(XRD)及透射电子显微镜(TEM)表征了急冷态和部分晶化后条带的结构,运用示差扫描量热仪(DSC)分析了合金的玻璃转变和晶化行为.结果表明,Al88Y6Fe6、Al84Y7Fe7、Al89Y5Fe6和Al88Y5Fe7可以形成完全非晶合金;Al88Y5Fe7非晶合金280℃等温退火30 min析出纳米尺寸Al晶体,370℃等温退火30 min Al晶体发生进一步长大并有金属间化合物析出.展开更多
文摘A thermodynamic study has been carried out on M-Si-B (M=Fe, Ni) ternary systems. A regular solution approximation based on the sublattice model was adopted to describe the Gibbs energy for the individual phases in the binary and ternary systems. Thermodynamic parameters for each phase were evaluated by using the experimental data. These parameters enabled us to obtain reproducible calculations of the isothermal and vertical section diagrams. The amorphous-forming ability of M-Si-B ternary alloys has been evaluated by introducing thermodynamic quantities obtained from the phase diagram calculations into Davies-Uhlmann kinetic formulations. For the computation, the time-temperature- transformation (TTT) diagram, which gives the time necessary for the formation of the detectable amount of crystal during transformation, was obtained at a finite temperature. The critical cooling rate for amorphization could be defined as the minimum cooling speed that does not intersect the TTT curve and, hence, these critical cooling rates enable us to evaluate the glass-forming ability of M-Si-B ternary alloys. The driving force for the crystallization of the crystalline phase was derived, on the basis of the thermodynamic functions of each phase formulated by the present study. The calculated results showed good agreement with the experimental data on the compositional range of amorphization in these alloy systems.
文摘采用单辊快速凝固法制备出Mg80 x Alx Cu15Y5(x=0,1)合金薄带,再将薄带在不同温度下进行退火处理,利用XRD、DSC和HRTEM分析Al元素对Mg80 x Alx Cu15Y5(x=0,1)合金薄带的非晶形成能力及热稳定性的影响。结果表明:Al的加入使得Mg-Cu-Y合金的玻璃转变温度和初始结晶温度升高,过冷液相区宽度ΔTx因Al部分置换Mg而增大,约化玻璃转变温度Trg从0.616升至0.631,合金的非晶形成能力及热稳定性提高。随着退火温度的升高,Mg79Al1Cu15Y5合金的晶化率低于Mg80Cu15Y5合金的。当退火温度为523 K时Mg80 x Alx Cu15Y5(x=0,1)合金均发生明显晶化,在非晶基体上弥散析出大量HCP-Mg和Mg2Cu纳米颗粒;当温度升高至573 K时,Mg79Al1Cu15Y5合金中有针状AlMg化合物相形成。
文摘为了分析Al-Y-Fe三元合金的玻璃形成能力和热稳定性,采用熔体急冷法制备了Al(100-2x)YxFex(其中x=3,4,5,6,7,8,9)、Al89Y5Fe6、Al88Y5Fe7和Al87Y5Fe8合金条带.利用x-射线衍射(XRD)及透射电子显微镜(TEM)表征了急冷态和部分晶化后条带的结构,运用示差扫描量热仪(DSC)分析了合金的玻璃转变和晶化行为.结果表明,Al88Y6Fe6、Al84Y7Fe7、Al89Y5Fe6和Al88Y5Fe7可以形成完全非晶合金;Al88Y5Fe7非晶合金280℃等温退火30 min析出纳米尺寸Al晶体,370℃等温退火30 min Al晶体发生进一步长大并有金属间化合物析出.
