脉冲电流处理对Fe_(73.5)Cu_1Nb_3Si_(13.5)B_9非晶薄带晶化和显微硬度的影响

INFLUENCES OF PULSING CURRENT ON CRYS-TALLIZATlON AND MICROHARDNESS OF Fe_(73.5)Cu_1Nb_3Si_(13.5)B_9 AMORPHOUS RIBBON

脉冲频率为50Hz、电流密度为1750A／mm2的高强脉冲电流使Fe73.5Cu1Nb3Si13.5B9非晶薄带在低于非晶转变温度100K的条件下实现了短时晶化,脉冲电流能促进原子迁移,加速原子和原子团扩散,使Fe73.5Cu1Nb3Si13.5B9非晶薄带发生结构弛豫,使显微硬度由原始态非晶的8．2逐渐增至约9．0,进一步延长脉冲电流作用时间,非晶薄带发生显著晶化,大量析出平均尺寸约为8．5nm的α-Fe(Si)相,其显微硬度则急剧增至12．4以上,增幅约达50％,在高强脉冲电流作用下, Fe73.5Cu1Nb3Si13.5B9非晶薄带可在约30s的时间内基本完成纳米晶化过程,而等温退火晶化则需要约1h．

Fe73.5Cu1Nb3Si13.5B9 amorphous ribbon can be significantly nanocrystallized by pulsing current treatment in a short time （within 30 s） at low temperature （100 K lower than glass transition temperature）. Under the action of high density pulsing current, the diffusibility of atoms has been enhanced. The microhardness of the amorphous alloy is increased by 10% （from 8.2 to 9.0） with respect to the initial ribbon, resulted by the structural relaxation induced by pulsing current treating. An abrupt increase of the microhardness by 50% （from 8.2 to 12.4） has been obtained in the specimen after increasing the treated time, which results from the precipitation of abundant α-Fe nanocrystals with an average grain size of 8.5 nm. Isothermal annealing needed 1 h but pulsing current treatment only about 30 s for full crystallization, indicating the latter is an effective way for the nanocrystallization of the studied amorphous alloy.