V替代Nb对FINEMET非晶合金结晶动力学的影响

Effect of V substitution for Nb on the crystallization kinetics of FINEMET amorphous alloys

利用标准的单辊甩带技术在大气环境下制备了Fe73.5Si13.5B9Cu1Nb3-xVx(x=1,2)非晶条带。利用非等温DSC测量研究了非晶条带的初始结晶动力学行为。采用Kissinger方法计算了非晶条带的初始结晶激活能,其数值分别是302kJ/mol(x=1)和364kJ/mol(x=2)。Avrami因子n的计算结果分别为2.35(x=1)和1.61(x=2),Avrami因子的计算结果表明,非晶条带非等温初始结晶的机理为扩散控制的低维生长,且其形核率不断降低。在793、823和853K下分别对非晶条带进行真空等温退火1h,从而在非晶基体中形成纳米晶相。XRD分析结果表明,823和853K下真空等温退火1h后,x=1和2非晶条带中析出的α-Fe(Si)相的平均晶粒尺寸分别为12.8、14.0、13.3和14.2nm。

Amorphous ribbons Fe73.5Si13.5B9Cu1Nb3-xVx（x=1,2）were prepared by the standard single copper wheel melt spinning technique in the air atmosphere.The primary crystallization kinetics of amorphous ribbons have been calculated by non-isothermal differential scanning calorimetry（DSC）measurements.The crystallization activation energies of amorphous ribbons have been calculated by using Kissinger plot method and their values were 302 and 364kJ/mol for x=1 and 2,respectively.The calculated Avrami exponents n were 2.35 and 1.61 for x=1 and 2,respectively.The values of the Avrami exponents showed that the crystallization mechanism in the non-isothermal primary crystallization of amorphous ribbons was all shapes growing from small dimensions controlled by diffusion at decreasing nucleation rate.The isothermal annealing was carried out at 793,823 and 853K for 1h in a vacuum furnace to induce the formation of nanocrystallite in amorphous ribbons.The X-ray diffraction（XRD）analyses showed that the average sizes of α-Fe（Si）grains for the alloy of x=1 are 12.8,14.0nm and those for the alloy of x=2 are 13.3,14.2nm when annealed at 823 and 853K,respectively.