Tb0.3Dy0.7(Fe1-xAlx)1.95合金显微组织及低磁场的磁致伸缩性能研究

研究了Al添加量变化对Tb0.3Dy0.7(Fe1-xAlx)1.95合金显微组织、磁致伸缩系数的影响.结果发现,随着Al添加量的增加,晶体显微组织中的析出物增加;在一定的磁场强度下,磁致伸缩系数随Al添加量而变化,当磁场强度低于40kA/m时,磁致伸缩系数随Al添加量的变化曲线出现一峰值,当磁场强度高于40kA/m时,磁致伸缩系数随Al添加量的增加而降低.     

Influence of Magnetic Heat Treatment and Compressive Stress on Jump Effect of Magnetostriction of Tb0.3Dy0.7Fe1.95 Alloy

Influence of Magnetic Heat Treatment and Compressive Stress on Jump Effect of Magnetostriction of Tb_(0.3)Dy_(0.7)Fe_(1.95) Alloy     

Tb对Fe_(83)Ga_(17)合金磁致伸缩性能影响

主要研究了Tb对Fe-Ga合金的磁致伸缩性能影响。添加Tb后,Fe-Ga合金具有100晶向取向的晶粒数目有所增加,使磁致伸缩性能有了明显的提高。研究了Tb在Fe-Ga合金中的存在位置,Tb原子在合金的晶界处富集。     

( Tb,Dy) Fe2合金表面离子注入渗氮改性及抗腐蚀性能研究

采用离子注入技术在(Tb,Dy)Fe2稀土超磁致伸缩材料表面引入氮离子进行改性处理,研究了加速电压对材料表面相结构、微观形貌、表面硬度、抗酸碱腐蚀性能及磁致伸缩性能的影响.结果表明:离子注入渗氮后,(Tb,Dy)Fe2合金表面的REFb相分解,生成了REN,α-Fe和Fe8N新相,材料表面微观形貌发生了明显变化,表面硬度明显提高.通过测试极化曲线研究了渗氮前后(Tb,Dy)Fe2合金在不同PH值NaCl溶液中的抗酸碱腐蚀性能,发现pH值相同条件下渗氮处理后(Tb,Dy) Fe2合金的自腐蚀电位Ecorr较渗氮前明显正移且有钝化现象发生.在加速电压140 kV,离子注入剂量5.0×1017 ion.cm -2条件下渗氮处理的(Tb,Dy)F合金,处于20℃,3.5％ NaCl溶液环境中,pH=4时,△Ecorr=0.23413 V; pH =7时,△Ecorr =0.18992 V; pH=10时,△Ecorr =0.01268 V,渗氮处理后(Tb,Dy)Fe2合金的抗酸腐蚀性能明显增强,抗碱腐蚀性能变化不明显.随着pH值的增大,渗氮与未渗氮(Tb,Dy) Fe2合金的抗腐蚀性能均变差.由于离子注入表面渗氮的渗氮层很薄,渗氮温度很低,渗氮处理没有破坏材料的内部基体结构,因此渗氮后材料渗氮处理没有破坏材料的内部基体结构,其磁致伸缩性能几乎未受影响.研究表明离子注入渗氮是(Tb,Dy)Fe2磁致伸缩材料表面改性的一种有效方法.     

Tb0.3Dy0.7（Fe,M）1.95合金的晶体轴向取向与磁致伸缩性能

研究了Tb_0.3Dy_0.7(Fe_1-x,M_x)_1.95(M=Mn,Al,B,Ti,x=0.03)合金在高温度梯度区熔定向凝固过程中,晶体轴向取向、结晶形貌随晶体生长速度的变化规律和不同晶体轴向取向与磁致伸缩应变之间的关系.结果发现,晶体生长速度由低变高时,晶体由平面晶向胞状晶、胞技晶、树枝晶生长转化.晶体也相应地由利<110>,<112>变化为<110>+<113>+<112>混合轴向取向.完全的<112>轴向取向可获得优异的磁致伸缩性能.     

Mn含量对RxR′1—xFey三元合金磁致伸缩性能影响的研究

采用水冷铜坩埚惰性气体保护电弧熔炼和浮区区域熔炼，在ＲｘＲ′１－ｘＦｅｙ三元合金中添加Ｍｎ元素，获得ＴｂＤｙＦｅＭｎ系合金棒材铸态试样，测量了其室温下的磁致伸缩系数，并采用电子探针显微分析仪和劳厄Ｘ射线衍射技术分析了其显微结构。就Ｍｎ含量对合金的影响及其最佳含量进行了分析研究，为超磁致伸缩材料的研制提供了理论依据     

Surface modification of （Tb0.3Dy0.7）Fe1.95 alloy by ion nitriding process

Effect of ion nitriding modification on surface hardness, corrosion resistance and magnetostriction of (Tb0.3Dy0.7)Fe1.95 alloy was investigated. Results demonstrated that a 100-200 nm thick nitrided layer was formed on the sample surface by ion nitriding treatment, which improved obviously surface hardness, wear, and corrosion resistance properties of (Tb0.3Dy0.7)Fe1.95 alloys. The surface hardness was increased from HV587 to HV622 after ion nitriding at 650 K for 6 h. Furthermore, ion nitriding treatment had almost no influence on mag-netostrictive performance as the nitrided layer was quite thin and the treatment temperature was not too high. The results might provide us a new approach for surface modification of (Tb0.3Dy0.7)Fe1.95 alloy.     

微量稀土元素Tb、La掺杂对Fe-Al合金结构和磁致伸缩性能的影响

为了研究微量稀土元素Tb和La掺杂对Fe81Al19合金结构和磁致伸缩性能的影响及影响机制,采用真空电弧熔炼法制备了Fe81Al19、Fe81Al19La0.1和Fe81Al19Tb0.1三种铸态合金。用X射线衍射仪(XRD)和扫描电镜联合能谱仪(SEM/EDS)分析了合金的微结构。用振动样品磁强计(VSM)和磁致伸缩测量仪测试了合金的磁性能和磁致伸缩系数。结果表明,Fe81Al19合金由单一的bcc结构A2相组成,而掺杂稀土后的Fe81Al19Tb0.1和Fe81Al19La0.1合金均由bcc结构的A2主相和少量富稀土相组成。稀土Tb和La的掺杂使Fe81Al19合金沿<100>晶向择优取向,且Fe81Al19Tb0.1合金择优取向更加明显。此外,三种合金的磁化功大小排序为:Fe81Al19Tb0.1> Fe81Al19La0.1> Fe81Al19。表明稀土元素掺杂导致Fe-Al合金具有更大的磁晶各向异性,且Tb的掺杂效果更加明显。磁致伸缩系数测试表明,与Fe81Al19合金相比,稀土掺杂合金的磁致伸缩系数明显增大,而且Fe81Al19Tb0.1合金的磁致伸缩系数增大的更加明显,大约是Fe81Al19合金的3.2倍,为86×10^-6。稀土掺杂合金磁致伸缩系数增大的原因主要源于掺杂稀土使Fe-Al合金沿<100>晶向择优取向和稀土导致合金具有高磁晶各向异性。     

成分及工艺对SmFe2系磁致伸缩性能的影响

研究了SmFe2合金中不同Sm、Fe比及添加Dy的磁致伸缩性能和力学性能,并且探讨了制备工艺和热处理对合金磁伸性能的影响.结果表明,Sm∶Fe为1∶1.87时,磁致伸缩性能最佳,用部分镝替代钐,可以提高材料的强度,热处理可以明显改善材料的磁致伸缩性能.     

Effect of Addition of Al on Crystal Structure Microtexture and Magnetostriction Coefficient in Tb0.3 Dy0.7 Fe1.95 Alloy

The effect of addition of A1 on crystal structure microtexture and magnetostrictioncoefficient in Tb0.3Dy0.7Fe1.95 alloy were studied.The results show that addition of A1 does not change crystal structure of alloy and the precipitates increase in the microtexture as addition of A1 increases.At a certain magnetic field, magnetostriction coefficient decreased as addition of Al increased.     

Relationship between crystal growth mode, preferred orientation and magnetostriction of (Tb0.3Dy0.7)Fe1.95 alloys

The relationship between crystal growth mode, preferred orientation and magnetostrictive properties of (Tb0.3Dy0.7)Fe1.95 alloys was investigated at different directional solidification rates. The results showed that preferred orientation had a strong influence on the characteristics of (Tb0.3Dy0.7)Fe1.95 alloys. At lower solidification rates, the sample with <110> preferred orientation showed larger low-field magnetostriction and apparent compressive stress effect. The excessive solidification rate resulted in failure of preferred orientation and a poor magnetostrictive performance. With an increase in solidification rates, the crystal growth modes changed gradually from cellular and primary dendrite morphology to developed dendritic morphology. In addition, domain configurations were observed using magnetic force microscopy, and the change of magnetostrictive properties was interpreted in terms of revealing the domain configurations.     

Effects of Magnetic Heat Treatment on Magnetostiction Properties of Tb0.3 Dy0.7 Fe1.95 Alloy

The effects of magnetic heat treatment on magnetostriction properties of Tb0.3Dy0.7Fe1.95 alloy were investigated.The directionally solidified alloy was heated to various temperatures near Curie temperature TC in vacuum, kept for a certain time under the application of magnetic field and then cooled to room temperature.The magnetostriction coefficient was measured by a resistance strain gage.The crystal structure was analyzed by X-ray diffraction (XRD).The experimental results show that the magnetostriction coefficient obviously increases and the grains orientations along the axis changed somewhat as the field of 1 T vertical to axis of the rod-shaped specimen is applied for 5 min at the heating temperature slightly lower than TC.     

Preparation and Magnetostriction of Tb0.22Dy0.48HO0.35Fe2 Alloys

Tb0.22Dy0.48Ho0.35Fe2 quaternary alloys are prepared by melting-top casting-annealing process. X-ray diffraction reveals that the alloy is single phase polycrystalline alloy with MgCu2 type cubic Laves phase structure, and (511) preferred orientation occurs in its. The magnetostriction measurements are carried out at room temperature using standard strain gauge technique in magnetic fields up to 400kA·m-1. The results show that when the magnetic field, H, is 90kA·m-1, the magnetostriction, λ ,of Tb0.22Dy0.48Ho0.35Fe2 quaternary alloys is 260×10-6, and when the H is 210kA·m-1, the λ is 438×10-6. When the H is 400kA·m-1, the λ is up to the saturation value, 538×10-6. As compared with TbDyFe ternary alloys, the λ of the quaternary alloy is significantly higher when the H is less than or equal to 210kA·m-1. When the H is 120kA·m-1,the λ of the alloy is 333×10-6,70×10-6 more than the ternary alloy. Research results and mechanism are discussed.     

Magnetostriction and Acoustics Properties of Tb1-xDyx(Fe1-yMny)1.95 Alloys and Their Application to Sonar Transducers

It was found in 1970s that Tbl -- x Dy.FeZalloys with C 15--type Laves phase structure had... [fi 1giant magnetostriction. Recent studies onthe substitution of Fe by other transition metalshave shown that magnetostrictive properties ofthe materials can he improved by the additionof transition metals. For example I the substitution of Mn for Fe in Tbl -- .Dy.FeZ alloys wasfound to increase the magnetostriction at lowmagnetic field and to influence the magnetocrystalline anisotropy of the r…