固溶體型Fe-Ga磁致伸縮材料具有低場大磁致伸縮特性,與具有本征脆性的化合物型REFe2相比,具有更好的延展性和溫度穩(wěn)定性,因此在致動器、傳感器和換能器等領域具有更好的應用前景,是近20年來磁致伸縮材料領域的研究熱點。由于Fe-Ga合金具有結構多樣性,且平衡態(tài)與亞穩(wěn)態(tài)的結構差異巨大,因此磁致伸縮性能對熱歷史非常敏感。然而,這種熱歷史敏感性的微結構根源富有極大爭議,成為該合金大磁致伸縮效應發(fā)現(xiàn)20年以來仍未解決的一個基礎問題。為此,本文選擇具有磁致伸縮峰值的成分Fe81Ga19進行研究,通過改變熱處理條件,采用X射線衍射、透射電子顯微鏡、光學顯微鏡、磁性測量和力學性能測試等手段,系統(tǒng)研究介于亞穩(wěn)和平衡態(tài)之間中間態(tài)的微結構和磁致伸縮性能差異,揭示了熱歷史敏感性的微結構根源,并在此基礎上提出了進一步提高磁致伸縮性能的策略。主要結果如下:首先,揭示了Fe-Ga合金磁致伸縮熱歷史敏感性的微結構根源。已有的研究表明,慢冷Fe-Ga合金的磁致伸縮性能遠低于高溫淬火態(tài),將其歸因于慢冷過程中形成了對磁致伸縮有害的D03有序相。然而,我們的對比研究表明,Fe81Ga19多晶樣品慢冷至A2固溶線附近溫度再淬火...

【文章頁數(shù)】：125 頁

【學位級別】：博士

【文章目錄】：
Acknowledgement
Dedication
Abstract
摘要
1 Introduction
    1.1 Background
    1.2 Magnetostriction and the proposed mechanisms for Fe-Ga alloy
    1.3 Investigations on the thermal history sensitivity of magnetostriction
    1.4 Motivation
2 Experimental Techniques
    2.1 Sample Preparation and heat-treatments
        2.1.1 Preparation of polycrystalline sample
        2.1.2 Heat-Treatments
    2.2 Microstructure Characterizations
        2.2.1 X-ray diffraction (XRD)
        2.2.2 Transmission Electron Microscopy (TEM)
    2.3 Magnetic measurements
    2.4 Mechanical tests
3 Microstructural origin of the thermal history sensitivity in slowly cooled FesiGai9
    3.1 Introduction
    3.2 Experimental Procedure
    3.3 Results and Discussion
        3.3.1 Magnetostrictive Properties
        3.3.2 Microstructure
        3.3.3 Discussion
    3.4 Conclusion
4 Search for maximum magnetostriction in Fe₈₁Ga₁₉ by quenching above and below thedecomposition phase boundary
    4.1 Introduction
    4.2 Experimental Procedure
    4.3 Results and discussion
        4.3.1 Magnetostrictive properties
        4.3.2 Microstructure
        4.3.3 Mechanical Properties
        4.3.4 Discussion
    4.4 Conclusions
5 Enhanced magnetostriction of Fe₈₁Ga₁₉ hot-rolled sheets by approaching an instablephase boundary
    5.1 Introduction
    5.2 Experimental Procedure
    5.3 Results and Discussion
    5.4 Conclusions
6 Conclusions and Perspectives
    6.1 Conclusions
    6.2 Perspectives
References
Publication list
Curriculum vitae



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