Slow nanocrystallization driving dynamics can be affected by the combination of two factors: sample residual stresses and sample geometry. This effect is evidenced at the initial stages of nanocrystallization of amorphous CoFeSiBCuNb magnetic microwires. Transmission electron microscopy observations indicate how crystallization at temperatures between 730 and 780 K results in a graded microstructure where the crystallization at the surface skin of the microwire, which remains almost amorphous, differs from that of the middle, where elongated grains are observed, and inner regions. However, samples annealed at higher temperatures present a homogeneous microstructure. The effect of gradient microstructure on magnetic properties has been also analyzed and a loss of bistable magnetic behaviour at low temperatures, from that obtained in the amorphous and fully nanocrystallized sample, has been observed and ascribed to changes in sign of magnetostriction for measuring temperatures below 100 K.
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机译：缓慢的纳米晶驱动动力学会受到两个因素的组合的影响：样品残余应力和样品几何形状。在非晶态CoFeSiBCuNb磁性微线的纳米晶化的初始阶段就可以证明这种效果。透射电子显微镜观察表明，在730 K和780 K之间的温度下结晶是如何形成渐变的微观结构的，其中几乎保持无定形的微丝表面表层的结晶与中间的（观察到拉长的晶粒）内部的结晶不同。地区。但是，在较高温度下退火的样品呈现出均匀的微观结构。还分析了梯度微结构对磁性能的影响，并且观察到低温下双稳态磁性能的损失，这是从无定形和完全纳米结晶的样品中获得的，并且归因于测量温度低于100时磁致伸缩的符号变化。 K.
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