铁基合金薄带多次等温回火特性的研究

The characteristics of multiple isothermal tempered Fe-based alloy ribbons

Fe基合金薄带的磁性能对应力敏感,特别是退火过程应力感生磁各向异性是否可以用回火方法消除,是一个令人感兴趣的科学问题.本文采用同步辐射X射线衍射技术,观测Fe73.5Cu1Nb3Si13.5B9非晶薄带经外加394.7 MPa应力540℃保温30 min退火后,进行多次等温回火样品的微观结构,用SupereyesB011型显微摄像机记录样品应力退火和回火过程的宏观伸长量,并利用HP4294A型阻抗分析仪测量相应样品的磁各向异性.对实验数据进行曲线拟合后发现,虽然应力退火过程的残余应力引起的晶格各向异性是产生磁各向异性的主要原因,但不是唯一原因,在应力退火过程中非晶基底的蠕变引起的纳米晶晶粒定向团聚,也是应力退火感生磁各向异性的重要原因;而且,因应力退火过程中非晶基底的蠕变引起纳米晶晶粒定向团聚感生的磁各向异性无法用等温回火方法完全消除.

The magnetic properties of Fe-based alloy ribbons are sensitive to stress,and it’s an interesting scientific question whether stress-induced magnetic anisotropy during annealing procedure can be eliminated by tempering.In this paper,the synchrotron radiation technique was used to observe the microstructure of Fe73.5Cu1Nb3Si13.5B9 amorphous ribbons annealed at 540℃for 30 minutes under 394.7MPa stress and tempered several times at the same temperature.The macroscopic elongation of the samples during stress annealing and tempering was recorded by SupereyesB011 microcamera,and the magnetic anisotropy of the samples was measured by HP4294A impedance analyzer.After fitting the experimental data,it is found that:(a)The lattice anisotropy,macroscopic strain and magnetic anisotropy of the sample show negative exponential attenuation with the tempering times,and their final residual are 19.04%.98.27%and 31.65%.(b)Multiple tempering can not completely eliminate lattice anisotropy,macroscopic strain and magnetic anisotropy induced by stress annealing.(c)The magnetic anisotropy of the sample has a linear relationship with the lattice anisotropy,but the intercept between the reverse extension line of the relation curve and the longitudinal coordinate is not zero.When the lattice anisotropy is zero,there is still 16.36%magnetic anisotropy.This is different from Ohnuma's conclusion that lattice anisotropy is the direct cause of magnetic anisotropy.(d)The structure anisotropy caused by the residual stress after stress annealing is the main cause of magnetic anisotropy,but it is not the only reason.The directional congregation of agglomerated nanocrystalline grains caused by creep of amorphous substrates during stress annealing is also an important cause of magnetic anisotropy induced by stress annealing.Moreover,the magnetic anisotropy induced by the directional congregation of agglomerated nanocrystalline grains due to the creep of amorphous substrates during stress annealing can not be completely eliminated by tempering.