RESEARCH ON MAGNETOVOLUME EFFECT AND INTERSTITIA ATOMS

典型铁基三因瓦尔合金x射线漫射散射的测量制备了Fe-Ni、Fe-Pt和Fe-Pd合金。在Fe-Pt Invar合金中未观察到漫射散射异常。在Fe-Pd Invar合金中观察到圆盘状的漫射散射。在Fe-Ni Invar合金中，沿oll方向观察到类似街道的异常漫射散射。发现这一异常的成因是由于铁原子在富铁浓度的小局部区域发生小位移，在低温马氏体由fcc相转变为bee相之前，通过磁体积效应产生沿oll平面的剪切应力。这种类型的小位移没有被任何其他方法检测到，只有目前的x射线漫射散射测量已经成功地通过铁原子的大磁体积效应观察到它，这是用三维电子的铁磁带理论解释的。研究了离子束辐照对铁基非晶态铁磁合金的影响，发现在辐照初期，铁基非晶态铁磁合金的高磁导率、低矫顽力等软磁性能得到改善。这一结果可以解释为在快速淬火阶段，非晶合金继承了感应磁各向异性与原始磁各向异性的竞争。此外，从高压下的磁性测量来看，磁性原子在与间隙原子相同的条件下表现出较大的磁体积效应。这一结果也可以用三维电子的铁磁带理论来解释。

Measurements of the X-ray diffuse scattering in typical Fe-base three Invar alloys ; Fe-Ni, Fe-Pt and Fe-Pd alloys were made.In Fe-Pt Invar alloy no anomaly in diffuse scattering was observed.In Fe-Pd Invar alloy a disc shape diffuse scattering was observed.In Fe-Ni Invar alloy a streek-like anomalous diffuse scattering was observed along Oll-direction.The origin of this anomaly is found to be caused by a shear stress along Oll-plane which is generated through the magnetovolume effect by small displacements of Fe atoms in a small local region where the Fe concentration is rich and the state is just before the martensitic transformation from fcc to bee phase takes place at low temperature.This type of small displacement was not detected by using any other method, and only the present X-ray diffuse scattering measurement has been successful to observe it through the large magnetovolume effect of Fe atoms, which is explained by using a ferromagnetic band theory of 3d electrons.The effect of ion beam irradiations on fe-base amorphous ferromagnetic alloys has been investigated, and an improvement of soft magnetic properties, such as high permeability and low coercivity, has been observed at an early stage of the irradiations.This result was explained as a competition of induced magnetic anisotropy with the original one which an amorphous alloy is inherited at the stage of rapid quenching.Furthermore, from the magnetic measurements under high pressures, magnetic atoms under the same condition as interstitial atoms show a large magnetovolume effect.This result was also explained by the ferromagnetic band theory of 3d electrons.