Ni51Zr49非晶合金晶化过程的电子显微镜研究

用透射电子显微镜对Ni₅₁Zr₄₉非晶合金的晶化过程进行了研究,发现晶化初期首先从非晶基体上析出的是具有C心单斜点阵的NiZr＇相,a=0.3268nm,b=0.4101nm,c=0.5224nm,β=71.8°。与稳定相NiZr有很明确的取向关系:[100]_NiZr＇∥[100]_NiZr [001]_NiZr＇∥[110]_NiZr。它可以看成是NiZr相的亚稳态或超结构。随温度升高,逐渐转变成NiZr相。温度再高时,在非晶基体上还会析出少量Ni₁₀Zr₇相。晶化初期,无论是NiZr还是NiZr＇相,都是以多次孪晶的形式析出。孪晶有这两种基本形式,一种是以NiZr或NiZr＇的[021]方向为轴的180°孪晶,一种是以NiZr的[001]或NiZr＇的[010]方向为轴的36°旋转孪晶,其它孪晶为这两种孪晶方式的重复与组合。随着温度的升高,孪晶逐渐减少。关键词：

TEM STUDY OF CRYSTALLIZATION BEHAVIOUR OF Ni51Zr49 AMORPHOUS ALLOY

The crystallization behaviour of Ni₅₁Zr₄₉ amorphous alloy has been studied by the transmission electron microscopy (TEM). It has been found that a metastable phase, NiZr, in rose-like morphology with C-centered monoclinic lattice, a = 0.3268, b = 0.4101, c = 0.5224nm and β= 71.8° in amorphous matrix in the earlier stage of the crystallization, The following orientation relationships between the metastable phase and the stable phase, NiZr, exist: [100]_NiZr＇//[100]_NiZr [001]_NiZr＇//[ll0]_NiZr. NiZr＇ phase is regarded as a metastable state of NiZr phase and transforms to NiZr phase gradually with an increase in temperature. A small quantity of Ni₁₀Zr₇ phase formed in the final stage of the crystallization. Both NiZr and NiZr＇ have complex twins with two principle typies, one of which is 180°twins with the [02l] direction of NiZr or NiZr＇ as axis and another 36°rotation twins with [001] of NiZr or [010] of NiZr＇ as axis. The total amount of twins decrease gradually with the increase in temperature.