高压下Fe_(84)Nb_7B_9纳米晶软磁块体合金的形成

Preparation of Fe_(84)Nb_7B_9 nanocrystalline soft magnetic bulk alloy under high-pressure

采用机械合金化(MA)以及低温高压烧结工艺制备了Fe84Nb7B9软磁合金粉末及其块体合金,并利用XRD、DSC、SEM对MA合金粉末和块体合金的相结构、晶粒大小以及组织的热稳定性进行了研究。结果表明:经过15hMA后,可获得单相bcc结构的粒径小于10nm的纳米晶过饱和固溶体粉末;在常压状态下,单相纳米晶过饱和固溶体合金在温度小于550℃时具有良好的组织热稳定性,温度小于770℃时具有良好的相热稳定性;在p=5.5GPa,t=3min条件下,当Pw≥820W时,可获得相对密度大于98.4%、单相bcc结构的纳米晶(粒径小于10nm)块体合金。

Fe_(84)Nb_7B_9 soft magnetic powders and bulk alloys were prepared by MA and low-temperature high-pressure sintering process, respectively. Phase structure, grain size and thermal stability of microstructure in MA powders and bulk alloys were studied by XRD, DSC and SEM. After MA for 15 h, nanocrystalline(less than 10 nm) supersaturated solid solution powders of single phase with bcc structure can be obtained. Under normal pressure, single phase nanocrystalline supersaturated solid solution alloys show excellent microstructure thermal stability and phase thermal stability at temperature being less than 550, 770 ℃, respectively; and under the conditions of p=5.5 GPa, t=3 min, when P_w≥820W, single phase bcc nanocrystalline(less than 10 nm) bulk alloys, which has relative density of more than 98.4%, can be obtained.