用经典的相变理论(J-M-A方程)导出了由核长大主导的非晶态合金晶化的峰值温度(T_P)与预存晶核密度(N_0)之间的关系式: T_P~2exp(-Eg/RT_P)=L/N_0~(1/3)其中Eg为核长大激活能,L为常数,R为气体常数.通过对非晶Ni-P合金的预退火处理,获得预存晶核密度不同的非晶态样品,在DSC上测量这些样品的晶化温度.结果表明,上述关系式与实验结果符合很好,利用此关系式可估算出核长大速率常数(U_0),讨论了预退火处理对晶化开始温度T_x及△T_(Px)=T_P—T_x的影响.
According to the classical theory of phase transformation, a relation-ship between crystallization temperature (the peak temperature in the exothermiccurve of crystallization, T_p) and the density of pre-existing nuclei in the sample,N_0, was derived in the crystallization process dominated by growth of nuclei: T_P~2exp(-E_g/RT_P)=L/N_0~(1/3)where Eg is the activation energy for growth of nuclei, L is a constant and R isthe gas constant. Different number of preexisting nuclei was formed by pre-anneal-ing treatment of a Ni-P glass at a temperature about 50K lower than crystalliza-tion temperature for different time. By means of a DSC determination, the crystal-lization temperature of as-quenched and the preannealed samples were obtained andit was found that the new equation successfully agrees with the experimental results.And the growth rate of crystal nuclei in the Ni-P glass can be estimated from therelationship. The onset temperature, T_x, decreases and the difference between T_p and T_x,△T_(px)=T_p-T_x, increases with the increase of annealing time.
参考文献
| [1] | |
| [2] | |
| [3] |
- 下载量()
- 访问量()
- 您的评分：
-
10%
-
20%
-
30%
-
40%
-
50%