The applicability of Johnson-Mehl-Avrami(JMA)model to the crystallization kinetics of Zr60Al15Ni25 bulk amorphous alloy is investigated by differential scanning calorimetry(DSC)under isochronal and isothermal conditio...The applicability of Johnson-Mehl-Avrami(JMA)model to the crystallization kinetics of Zr60Al15Ni25 bulk amorphous alloy is investigated by differential scanning calorimetry(DSC)under isochronal and isothermal conditions.A criterion xm,at which a defined function z(x)exhibits the maximum value,is introduced to check the validity of JMA model to the kinetics analysis.The value of xm has a constant of 0.632 for JMA model.It is found that the values of xm at different isothermal annealing temperatures(743,748,753 and 758 K)are almost near 0.632,which indicates that the isothermal crystallization kinetics can be modeled by JMA equation.However,the values of xm at different heating rates(10,20,30 and 40 K/min)are about 0.52,implying that JMA model is not valid to the isochronal crystallization kinetics.The reason why the JMA model is not valid to the isochronal crystallization kinetics is discussed.展开更多
基金Project (50804032) supported by the National Natural Science Foundation of ChinaProject (2008011046) supported by the Natural Science Foundation of Shanxi Province, ChinaProject (20080321036) supported by the Key Technologies R & D Program of Shanxi Province, China
基金Project(20051032)supported by the Natural Science Foundation of Shanxi Province,ChinaProject supported by the Shanxi Provincial Foundation for Leaders of Disciplines in Science and the Doctoral Science Foundation of Taiyuan University of Science and Technology,China
文摘The applicability of Johnson-Mehl-Avrami(JMA)model to the crystallization kinetics of Zr60Al15Ni25 bulk amorphous alloy is investigated by differential scanning calorimetry(DSC)under isochronal and isothermal conditions.A criterion xm,at which a defined function z(x)exhibits the maximum value,is introduced to check the validity of JMA model to the kinetics analysis.The value of xm has a constant of 0.632 for JMA model.It is found that the values of xm at different isothermal annealing temperatures(743,748,753 and 758 K)are almost near 0.632,which indicates that the isothermal crystallization kinetics can be modeled by JMA equation.However,the values of xm at different heating rates(10,20,30 and 40 K/min)are about 0.52,implying that JMA model is not valid to the isochronal crystallization kinetics.The reason why the JMA model is not valid to the isochronal crystallization kinetics is discussed.
