(Fe_(81)Ga_(19))_(99)B_1合金富Ga相淬火保温粗化现象及其对力学和磁致伸缩性能的影响

Coarsening phenomenon of Ga-rich phase in(Fe_(81)Ga_(19))_(99)B_1 alloy during heat preservation of quenching and its effects on mechanical and magnetostrictive properties

以(Fe81Ga19)99B1合金为对象,研究了不同热处理条件下合金析出相形貌和大小分布特征及其对力学性能和磁致伸缩性能的影响。结果表明,在1000℃下保温5 min^4 h的条件范围内,合金中细小富Ga析出相的平均尺寸随保温时间的延长由铸态的约1.2μm增加到约3.6μm;保温时间从4 h延长至12 h,析出相平均尺寸基本保持不变;与铸态试样相比,1000℃保温4 h后淬火态试样的维氏硬度下降了28.0%,变形抗力下降了11.9%(工程应变0.18时),表明析出相的粗化使合金呈现出软化特征;1000℃保温5 min后淬火试样的磁致伸缩系数比铸态试样提高51.2%,1000℃保温时间≥4 h淬火试样的磁致伸缩系数比1000℃保温5 min试样进一步提高了30.0%以上,即淬火保温时间延长导致析出相的粗化有利于合金磁致伸缩性能的提高。

Effects of morphology and size of precipitates in （Fe_（81）Ga_（19））_（99）B_1 alloy under different heat treatment conditions on its mechanical and magnetostrictive properties were investigated. The results show that the average size of the fine Ga-rich precipitates increases from 1.2 μm to about 3.6 μm with the extension of the holding time from 5 rain to 4 h at 1000 ℃. When the holding time increases from 4 h to 12 h, the average size of the precipitates is basically unchanged. Compared to the as-cast sample, the Vickers hardness and the deformation resistance of the alloy quenched at 1000 ℃ for 4 h decrease by 28.0% and 11.9% （ at engineering strain of 0. 18） , respectively, which indicates that the coarsened Ga-rieh precipitates can soften the alloy. The magnctostriction coeficient of the sample quenched at 1000 ℃ for 5 min increases by 51.2% compared to that of the as-cast one. If the holding time extends to 4 h, the magnetostriction coefficient of the alloy can be further improved by more than 30.0% compared to that of the sample with the holding time of 5 min. Therefore, coarsening the Ga-rich precipitate phases by the extension of the holding time is advantageous to the improvement of the magnetostrictive properties of （Fe_（81）Ga_（19））_（99）B_1 alloy.