Fe_3Ga合金纳米丝的结构和磁性

<正>Muhammad Irfan等人研究了退火温度对直径为80nm的电沉积Fe_3Ga纳米丝结晶结构相变化、有效各向异性能及磁化影响。采用扫描电镜EDX谱线测定Fe_3Ga纳米丝元素分布,清晰地显示出Fe和Ga的均匀分布,纳米丝间整齐排列,几何形状比值很高,纳米丝晶体结构同烧结温度关系极大。X-射线衍射表明,合成态Fe_3Ga纳米丝呈现明显A2无序相,由DO_3和LI_2析出物组成。随退火温度升高,明显无序相A2或短程有序相DO_3显著减少,晶粒沿稳定LI2相织构化排列,有少量DO_3相析出物。退火热处理     

热处理工艺对NiTi合金负热膨胀行为的影响

通过测定热膨胀系数研究了热处理工艺对NiTi合金负热膨胀（NTE）行为的影响，并采用XRD和TEM分析对其机理进行了探讨。研究表明：360℃，130h约束时效时，随着外加应力的增加，NiTi合金的负热膨胀系数先增后减，在250MPa时可获得峰值-87．0×10^-6K^-1；时效温度升高或高温下时效时间延长，其NTE行为变差。母相中Ti3Ni4相定向析出所形成的内应力场有效控制了相变的发生并促使产生体积变化和双程形状记忆效应，二者的联合作用导致了NTE行为的产生。     

Fe_3Al和FeAl合金的高温氧化行为

研究了含Nb、Nb和Cr的Fe_3Al合金,含Zr的FeAl合金在1050℃的氧化行为。结果表明Fe_3Al和FeAl合金氧化增重均符合抛物线规律。对于Fe_3Al合金,氧化层由Al_2O_3和Fe_2O_3组成;加入少量Nb,增加了氧化层的粘附性,从而改善合金的抗氧化性。对FeAl合金,氧化层为Al_2O_3;Zr的加入,虽然引起合金的内氧化,但却提高Al_2O_3的粘附性。     

热处理对ZK60复合材料热膨胀行为的影响

通过粉末冶金法制备ND+Mg_2B_2O_(5w)/ZK60复合材料,将所得复合材料以挤压比12∶1进行挤压,而后分别对挤压态的复合材料进行时效、淬火及退火热处理。首先,对这3种热处理态的复合材料进行循环数为10次的热循环试验(温度范围30~400℃,升温速率为5℃/min);然后,利用热膨胀仪研究热处理对该复合材料热膨胀行为的影响。结果表明,淬火态复合材料应变锯齿化现象最小,时效态次之,退火态最为明显,且3种热处理态的应变锯齿化现象均小于挤压态。此外,挤压态复合材料的热循环滞后环闭合程度也略差于3种热处理态的复合材料,且热膨胀系数大于热处理态复合材料。     

冷轧态Ti-35Nb-2Zr-0.3O合金的异常热膨胀行为

采用高真空非自耗电弧熔炼炉对Ti-35Nb-2Zr-0.3O (质量分数,%)合金进行熔炼。运用OM、XRD、SEM、TEM和静态热机械分析仪对Ti-35Nb-2Zr-0.3O合金进行表征,研究冷轧形变对合金显微组织及热膨胀行为的影响。结果表明:Ti-35Nb-2Zr-0.3O合金在冷轧过程中产生应力诱发马氏体α"(stress-induced martensiticα",SIMα")相,并形成平行于轧制方向的强110织构。等轴晶组织的Ti-35Nb-2Zr-0.3O合金表现出正常的热膨胀行为。形变后,合金的热膨胀行为出现异常现象,轧制方向表现为负膨胀,负膨胀程度随着形变量的增加而增大,截面方向表现为大于固溶态的正膨胀。30%形变合金的轧制方向在室温到250℃具有Invar效应,这一现象归因于SIMα"相变、晶格畸变和110织构的形成。冷轧态Ti-35Nb-2Zr-0.3O合金在室温到110℃的异常膨胀归因于SIMα"相到β相的晶格转变,而在高于110℃的异常膨胀行为归因于ω相和α相的析出。     

热处理温度对G3合金晶间腐蚀行为的影响

研究了不同退火温度对G3合金晶间腐蚀行为的影响,结果表明:G3合金经500 ℃退火后仅在晶粒内部生成极少量的γ'析出相,同时热处理部分或全部消除了试样的残余应力,使得500℃退火试样失重比固溶态试样还要少.700℃退火后晶内和晶界均有析出相生成,腐蚀速率最大.900℃退火时析出相已大量在再结晶区域生成,组织的均一性较700℃退火热处理好.     

长程有序金属间化合物FeAl和Fe_3Al合金的高温氧化行为

本文用等温氧化法研完了FeAl、FeAl+lat%B和FeAl+4at%Si以及Fe_3Al,Fe_3Al+4at%Si和Fe_3Al+4at%Mo合金的高温氧化行为。结果表明,FeAl及其合金在1000℃的氧化动力学服从抛物线规律。3种FeAl合金100h的氧化增重仅及1Cr18Ni9Ti不锈钢的三分之一。Si使氧化增重增加,B改善后期(约90h以后)的抗氧化性能。X-射线衍射分析表明,氧化膜均为单一的α-Al_2O_(30)Fe_3Al及其合金经540℃,100h氧化后,前者氧化增重类似于1Cr18N     

热处理制度对Ni53Mn23.5Ga21.5Ti2合金显微结构和相变行为的影响

研究了不同热处理工艺下Ni53Mn23.5Ga21.5Ti2铁磁性形状记忆合金的显微结构和相变行为.利用SEM、TEM、DSC和XRD等考察了Ni53Mn23.5Ga21.5Ti2合金中热处理制度对马氏体相变和组织结构的影响.结果表明:Ni53Mn23.5Ga21.5Ti2合金经1273 K,5 h热处理时有序度最高,呈单相结构.合金经1123 K,24 h热处理后在晶内和晶界上弥散分布着大量的析出相.经1473 K,5 h热处理时合金有序度很低,说明此时合金部分或全部熔化.在不同的热处理制度下合金的晶体结构并不改变,仍呈现5M的马氏体晶体结构.     

合金元素对Fe_3Al和FeAl合金力学性能的影响SCIEI

本文研究了Mo,Si,B和化学计量成分对Fe_3Al和FeAl合金室温和高温拉伸性能以及组织结构的影响,结果表明,三种合金元素都使两种铁铝化物得到明显强化,但Mo和Si使其严重变脆,硼使FeAl增加塑性,断口由沿晶型变为穿晶准解理型。富Al的Fe_3Al和富Fe的FeAl合金室温塑性较化学计量化合物有明显提高。Fe_3Al从400—550℃,FeAl从400—500℃出现反常温度关系,用组织结构方面的结果对此进行了讨论。     

Cu-Zn合金高压热处理后的组织演化及热膨胀性能

利用膨胀仪测试了Cu-Zn合金高压热处理前、后在25～700℃的热膨胀系数;采用金相显微镜﹑X射线衍射仪及差示扫描量热分析仪对Cu-Zn合金高压热处理前、后的组织进行研究;探讨高压热处理对Cu-Zn合金的组织及热膨胀性能的影响。结果表明：高压热处理能细化Cu-Zn合金的组织,增大Cu-Zn合金的热膨胀系数,同时,也能使Cu-Zn合金的热膨胀系数在α-T曲线上出现高峰值,且压力越大,热膨胀系数峰值越小。     

熔体快淬法制备Fe81Ga19磁致伸缩合金

采用GaIn合金冷却液体作为冷却介质,将Fe81Ga19熔体快淬制备出具有晶粒沿径向生长的合金棒.利用XRD极图反射法判定棒轴为[110]方向.通过热分析和XRD测试结果,结合相图分析可知,合金为A2无序体心立方相,热处理未改变合金的A2结构,但在690℃附近发生了A2相的Curie转变.合金棒材在无轴向压力条件下获得饱和磁致伸缩值为66×10-6;在加压条件下磁致仲缩出现明显的压力效应,在50 MPa下饱和磁致伸缩增加到115×10-6.     

Mechanisms of anelasticity in Fe–13Ga alloy

Thermally activated frequency and temperature dependent anelastic effects in Fe–Ga alloys are practically not studied as yet in spite of the capacity of these alloys to dissipate energy of mechanical vibrations due to magneto-mechanical damping. In this paper we have studied iron-based composition with 13 at.% Ga. Several thermally activated peaks have been discovered and their activation parameters are evaluated by means of temperature and frequency dependent internal friction tests using free-decay and forced vibrations. Physical mechanisms are proposed for most of these peaks. In addition to thermally activated relaxation peaks, an irreversible internal friction peak is recorded due to structural transformation around 200 °C. This peak is frequency independent and is accompanied by inverted modulus behaviour. High damping capacity of Fe–13Ga alloy is confirmed.     

Effect of Dy doping on magnetostrictive and mechanical properties of Fe83Ga17 alloy

Fe_(83)Ga_(17) alloy is a kind of promising magnetostrictive alloys with high magnetostrictive properties and a low saturation magnetic field. As-cast Fe_(83)Ga_(17) Dyx(x=0, 0.05, 0.1, 0.2, 0.4) polycrystalline alloys were prepared by arc melting. Effect of Dy doping on the microstructure, magnetostrictive and mechanical properties of as-cast Fe_(83)Ga_(17) alloy was investigated. Results show that Dy-doped alloys exhibit a dual-phase structure containing the A2 matrix and Dy-rich precipitates(Fe_(56)Ga_(34)Dy_(10)). Both magnetostriction and mechanical properties of Fe_(83)Ga_(17) alloys are improved by Dy doping. A small amount of Dy addition(x=0.2) significantly causes Fe_(83)Ga_(17) alloy to transform from typical brittle material(fracture strain ε1%) to plastic material(ε≈11%). Correspondingly, the fracture mode transforms from intergranular fracture to dimple fracture. At the same time, the ultimate tensile strength and the magnetostriction rise up to 209 MPa and 64 ppm, respectively. Dy-rich precipitates disperse along the grain boundries and inside the grains, which plays an important role in the grain refinement and solution strengthening, and therefore, contribute to the enhancement of mechanical properties of the alloy. The improvement of magnetostriction could be attributed to the large lattice distortion induced by Dy atoms entering into the A2 matrix. Doping Dy into Fe-Ga alloys provides an effective solution to the brittleness in their applications.     

In,Ge添加对Fe81Ga19合金磁致伸缩系数的影响

研究了Fe81(Ga1-xYx)19(Y=In,Ge;x=0,0.1)合金的相结构,微观结构和磁致伸缩性能.结果表明:铸态和淬火态Fe81Ga19为A2相单相结构,微观组织是均匀的等轴晶;添加In后,合金由A2和富In相两相组成,富In相呈细小的颗粒状沿晶界分布,淬火后,富In相数量减少;添加Ge后,合金保持了A2相结构,晶格常数减小,铸态Fe81(Ga09Ge01)19合金中存在大量的枝晶,淬火后枝晶消失,成为均匀的等轴晶.铸态Fe81Ga19合金的磁致伸缩系数为3.3 ×10-5,淬火后提高到了7.2 ×10-5;添加In后,合金的磁致伸缩系数降低,淬火态Fe81(Ga0.99In0.1)19合金的磁致伸缩系数较热处理前提高了约1倍;添加Ge后Fe-Ga合金的磁致伸缩系数降低,与铸态Fe81(Ga0.9Ge0.1)19合金相比,淬火后磁致伸缩系数提高了约2倍.     

Effect of denucleating glass composition on undercooling of Fe83Ga17 alloy melts

Adopting glass fluxing combined with superheating cycling method, the undercooling and its stability of Fe₈₃Ga₁₇ alloy melts were investigated using different kinds of denucleating glass: B₂O₃, 90% NaSiCa + 10% B₂O₃ (simplified as Na–Si–Ca–Al–B) and 70% Na–Si–Ca–Al–B + 30% Na₂B₇O₄. The results showed that different glass has different denucleating mechanism. The purification of B₂O₃ glass is only a physical process, by which the stable bulk undercooling cannot be obtained during superheating–cooling cycles. While taking Na–Si–Ca–Al–B glass as purifying agent, its denucleating mechanism is a comprehensively physicochemical process. But the stability of undercooling is still undesirable because of the separation between melt and glass during cooling process in superheating cycling. A stable bulk undercooling can be obtained by physicochemical denucleating process in the case of 70% Na–Si–Ca–Al–B + 30% Na₂B₇O₄ molten glass owing to its suitable viscosity.     

热处理对Fe84Ga16合金薄膜中内应力的影响

采用磁控溅射技术制备了Fe₈₄Ga₁₆薄膜并进行了退火处理,用SEM 和XRD研究了薄膜的显微结构和内应力,计算了溅射态和退火态薄膜的内应力。结果发现,溅射态和退火态薄膜都以A₂相存在,并随着退火温度的升高,择优取向变得愈加不明显。与退火后的薄膜相比,溅射态薄膜内应力更大,且为压应力。低温退火后,薄膜内应力有一定程度的减小,随着退火温度的升高,薄膜内应力又逐渐回升,但回升的幅度不大。     

Fe3Al合金的钎焊性能试验研究

分别采用铜基钎料及工业纯铝1060(L2)作中间层在空气炉中进行Fe3Al合金的钎焊试验。试验结果表明：采用铜基钎料钎焊Fe3Al合金与18—8钢试样,钎料对母材的润湿性良好,且在Fe3Al合金一侧出现Cu的晶间渗入现象及微裂纹;采用纯铝箔作中间层钎焊Fe3Al合金,接头区域有明显的扩散反应区,通过对接头区的显微硬度进行测定,并结合X射线衍射分析结果,发现在接头处有高硬度的脆性相(Fe2Al5)生成。     

激光冲击强化ZCuAl10Fe3Mn2合金的热疲劳裂纹生长行为

为了提高高温构件的热疲劳性能、减少表面裂纹,研究激光冲击对ZCuAl10Fe3Mn2合金硬度、表面形貌、残余应力和热疲劳性能的影响.采用扫描电子显微镜(SEM)和能谱仪(EDS)分析合金的显微组织和裂纹形貌.结果表明:在4 J脉冲能量下,激光冲击能显著改善合金的热疲劳性能.在热应力和交变应力的作用下,试样缺口附近组织氧...     

Welds of Fe3Al-type alloy with hardened structure

Tungsten inert gas welding (TIGW) of Fe₃Al-type alloy sheets includes heat treatment resulting in the nucleation of carbide particles. Mechanical tests (tensile experiments, creep at high temperatures and hardness tests at room temperature) proved that (Fe,Cr) carbide precipitates harden the welded material to the level of the unwelded material.