材料期刊网

<正> 调幅组织(modulated structure)可以通过调幅分解(spinodal Decomposition)而产生,使合金获得成分不同的呈周期规则排列的两相结构;它也可通过形核-长大机制,即在长大(或粗化)过程中由于各向异性的共格应变能的作用,形成有取向的规则排列的两相组织。因此相分解的两种机制:调幅分解和形核-长大,在相变后期都可获得几乎相同的调幅组织,难以区分。 有人认为电子衍射中出现卫星反射(Satellite)(或X衍射中出现边带)和TEM

The modulated structure developed during early aging stage in Ni-38Cu-6Si and Ni-60Cu-4Cr (by at.-%) alloys have been studied by TEM in different operating conditions It has been shown that the features of wavy striation contrast in image and satellites in diffraction patterns were viewed in both Ni-Cu-Si and Ni-Cu-Cr alloys But the diserete particles distributed randomly with sharp interphase boundaries were detected in initial stages of aging by using the technique of defocussing high order reflection in bright field. However, they arrayed periodically along <100> direction after some aging time. Accordingly it is suggested that the modulated structure formed by aging at 580℃ in the two alloys is not due to spinodal decomposition The distinguishing criterions between spinodal reaction and nucleation-growth have been discussed.