The lattice parameters and microstructures of annealed,nickel-rich nickel-molybdenum alloys

Metallographic and X-ray studies conducted at room temperature on annealed, nickel-rich nickel-molybdenum alloys indicate that ∼ 10.5 at % Mo is soluble in the α (fcc) phase. The lattice parameter of this phase is given bya ₀ (26.5±1°C)=0.000 409 × at % Mo+0.352 48 nm. Grain- and twin-boundary nucleated volumes of the β (Ni₄Mo) phase were observed in samples with 15 to 20 at % Mo and co-existed with a discontinuous, nearly lamellar, precipitate in samples with 17.5 and 20 at % Mo.     

Effect of C content on the mechanical properties of solution treated as-cast ASTM F-75 alloys

The mechanical properties of solution treated ASTM F-75 alloys with various carbon contents have been studied. Alloys cast under the same conditions were subjected to solution treatment for several periods and then their tensile properties were evaluated. In the as-cast conditions, the alloys exhibited higher strength values with increasing carbon content whereas their ductility was not significantly affected. For the solution treated alloys, the variation of the strength was characterized by a progressive increase for short treatment times until a maximum value was achieved, which was followed by a diminution in this property for longer treatment times. This behavior was more accentuated for the case of the alloys with medium carbon contents, which also exhibited the highest values of strength. Furthermore, the alloy’s ductility was enhanced progressively with increasing solution treatment time. This improvement in ductility was significantly higher for the medium carbon alloys compared with the rest of the studied alloys. Thus, high and low carbon contents in solution treated ASTM F-75 alloys did not produced sufficiently high tensile properties.     

Effects of rare earths on properties and microstructures of lead-free solder alloys

In order to further enhance the properties of lead-free solder alloys such as SnAgCu, SnAg, SnCu and SnZn, trace amount of rare earths were selected by lots of researchers as alloys addition into these alloys. The enhancement include better wettability, physical properties, creep strength and tensile strength. For Sn3.8Ag0.7Cu bearing rare earths, when the rare earths were La and Ce, the creep-rupture life of solder joints can be remarkably improved, nine times more than that of the original Sn3.8Ag0.7Cu solder joints at room temperature. In addition, creep-rupture lifetime of RE-doped solders increases by over four times for SnAg and seven times for SnCu. This paper summarizes the effects of rare earths on the wettability, mechanical properties, physical behavior and microstructure of a series of lead-free solders.     

Influence of oxygen content on magnetic properties of Fe-Ni alloys

58-percent Ni-Fe alloys have been investigated. It was found that the magnetic properties of the alloys depend on the whole chemical composition: matrix + alloying + impurity. The amount of impurities may be influenced deliberately by a proper selection of the atmosphere, temperature and time of the heat treatment. The effect of magnetic annealing was also investigated. Approximately linear relationship was found between the induced anisotropy constant and the suitably weighted average of oxygen and carbon contents. Our measurements suggest that the total amount of impurities in interstitial solid solution has an influence on value of the induced anisotropy constant.     

碳纳米管负载FeCoNi纳米复合材料的制备及磁性研究

采用湿化学法制备了碳纳米管负载组成可控的FexCo81-xNi19纳米复合材料,用XRD、TEM、SAED和EDX等技术进行表征,并用VSM测试样品的磁性能.结果表明,FexCo81-xNi19合金以颗粒状均匀分散在碳纳米管表面;当x=21、33、46时,FeCoNi合金均为体心立方和面心立方两相共存;其磁性能与合金的组成密切相关,随着合金中Fe含量的增加,矫顽力(Hc)下降,饱和磁化强度(Ms)显著增加;当x=46时,合金的磁性能最佳.     

退火温度对SmCo永磁薄膜微结构及磁性能的影响

采用直流磁控溅射法制备SmCo薄膜,研究了退火温度对薄膜微结构及磁性能的影响。XRD分析结果表明,当退火温度为600℃时,SmCo5相析出,而Sm2Co17相在700℃析出。SEM照片可看出,退火温度高于900℃时,六方柱状的SmCo5相和菱方状的Sm2Co17相全部析出。随着退火温度的升高,晶粒尺寸增大,当温度达940℃时,晶粒尺寸减小,而在980℃时,晶粒尺寸又将增大。VSM测试表明,与制备态的薄膜相比,退火后的薄膜在垂直于膜面方向的矫顽力、剩余磁化强度及最大磁能积都增大。960℃时得到矫顽力和剩余磁化强度的最大值,800℃时得到最大磁能积的最大值。     

Effect of Zn content on the microstructures and mechanical properties of laser beam-welded ZK series magnesium alloys

The effect of Zn content on the microstructures and mechanical properties of laser beam welded ZK series magnesium alloys (ZK21, ZK40, and ZK60) has been studied. Owing to the lower heat input, laser beam welding can successfully be employed to weld ZK series magnesium alloys having Zn content up to 4 wt%, which are difficult to weld by means of conventional arc welding. However, ZK60 is susceptible to solidification cracking and presents a poor weldability, which may originate from the net-like distribution of more Mg₅₁Zn₂₀ precipitates along grain boundaries (GBs) in the fusion zone (FZ). With increasing Zn content, the amount and size of precipitates along GBs in the FZ increase, and the morphology of grains in the FZ adjacent to fusion boundary changes from cellular to equiaxed dendritic. The grains in the FZ of ZK40 alloy are the finest among the three alloys, whose size is only about 4.8 μm, and the ZK40-welded joint achieves the highest ultimate tensile strength of 312 MPa, which is up to 90.4% of the base metal.     

The effects of carbon on the magnetic properties of nanocrystalline Fe-based alloys

We investigate the magnetic properties of nanocrystalline Fe_73.5Cu₁M₃Si_13.5B₉ (M=Nb or Mo) alloys when C is substituted for B up to 2 at%. It is found that the permeability and coercivity deteriorate with the content of C in the case of both M=Nb and Mo. The saturation magnetization also deteriorates as C is substituted for B in the case of M=Mo but it improves linearly with the C content in the case of M=Nb. This increase in the saturation magnetization of the Fe-Cu-Nb-Si-B alloy with C addition can provide an opportunity to overcome one of the main disadvantages, low magnetic flux density, of the alloy. In the latter part of the work we also investigate the magnetic properties of Fe_76.5–y Cu₁Nb_y (Si_0.5B_0.4C_0.1)_22.5 (0y3) alloys, particular emphasis being given to the role of Nb in the presence of C. It is found that C may help Nb to suppress the growth of -Fe grains in the alloy.     

Effects of the heat treatment on the microstructures and magnetic properties in Alnico 5

In Alnico 5, cooling rate c in a magnetic field from 900°C to 600°C and optimum aging time t at 600°C have the relation of log(t) = 0.417 log (c) + 0.884. However the final magnetic properties are highly dependent on the cooling rate. Spinodally decomposed structures of this alloy show that the faster the cooling rate the smaller the size of the FeCo-rich precipitates and the larger the aspect ratio without change of the volume fraction of the precipitates. The length of the long axis of the FeCo-rich precipitates at a given cooling rate is not uniform due to the interconnection of the subsequent precipitates by the magnetic field effect, and this tendency seems to be stronger when the cooling rate is slower. However the length of the short axis of the precipitates is almost the same at a given cooling rate. The length of the short axis l and the cooling rate c in a magnetic field have the relation oflog (l) = 2.385 - 0.317 log (c). Optimum solution treatment temperature of the low-temperature treatment method was 860°C. This method has higher coercive force than that of the high-temperature treatment method. The FeCo-rich precipitates of the specimen were aligned more parallel to the applied magnetic field with little interconnection of the precipitates and have a higher aspect ratio than that of the high temperature treatment specimen.     

Low-temperature elastic properties of four wrought and annealed aluminium alloys

The elastic properties of four annealed polycrystalline commercial aluminium alloys were studied between 4 and 300 K using a pulse-superposition method. Results are given for longitudinal sound velocity, transverse sound velocity, Young's modulus, shear modulus, bulk modulus (reciprocal compressibility), Poisson's ratio, and elastic Debye temperature. The elastic stiffnesses of the alloys increase 4 to 13% on cooling from room temperature to liquid helium temperature. The elastic constant-temperature curves exhibit regular behaviour.     

Effects of calcium on the microstructures and tensile properties of Mg-5Li-3Al alloys

The as-cast Mg-5Li-3Al-xCa (x = 0, 0.5, 1, 1.5 wt.%) was prepared with vacuum induction melting furnace, then processed by hot extrusion. The microstructures and tensile properties were investigated. The results show that the grains of as-cast alloys were refined gradually with the increase of Ca content from 0.5 wt.% to 1 wt.%, while the Ca content increases to 1.5 wt.%, the grain size increases. The microstructures of investigated alloys were further refined after hot extrusion. Both as-cast and as-extruded Mg-5Li-3Al-0.5Ca alloys have the highest mechanical properties, which is mainly attributed to the grain refinement caused by the addition of Ca and the formation of strengthening phase, Al₄Ca. When the addition of Ca is up to 1-1.5 wt.%, the tensile properties of alloys are worsened due to the excessive (Mg, Al)₂Ca eutectic phase forming at grain boundary.     

Ni的合金化对Cu-Co合金磁学性能和GMR效应的影响

磁学性能分析表明，Cu85Co15熔体快淬过程中即可通过液相分解形成大块铁磁性富Co相，也可通过固相分解形成纳米超顺磁相，而Cu80Co15Ni5合金则主要通过固相分解形成纳米超顺磁相。Ni对Cu—Co合金液相分解的抑制和增加固容体过饱和度从而促进过饱和固容体分解的作用使Cu80co15Ni5合金相对于无Ni的Cu85Co15合金时效后纳米超顺磁相尺寸减小，体积密度明显增高。Ni合金化还使Cu—Co合金富Co磁性相的尺寸一致性得到很大改善，减小了磁性相间的交互作用。这些因素都有助于增大GMR效应。     

Phases,microstructures and properties of multi-component FeCoNi-based alloys

ABSTRACT

Disordered and ordered solid solution phases are identified in FeCoNi-based multi-component alloys. An ultimate strength of 2380?MPa was achieved in the dual face-centered cubic?+?body-centered cubic structural (FeCoNi)₆₀Al₁₅Cr₂₅ alloy, accompanied by a fracture strain of 38% and a hardness of 376.3?HV. After holding at 900°C for 100?h, oxidation resistance of the alloys follows by an increasing rank of (FeCoNi)₈₅Al₁₅?<?(FeCoNi)₇₅Cr₂₅?<?(FeCoNi)₆₀Al₁₅Cr₂₅. Moreover, the oxidation kinetic curves of the alloys follow a power-law dependence. (FeCoNi)₆₀Al₁₅Cr₂₅ alloy shows a good trade-off of mechanical properties and an excellent oxidation resistance at evaluated temperature, and can be a potential candidate for high temperature materials.     

Effects of gas nitridation on microstructures and magnetic properties of Fe3N/Fe soft magnetic composites

Journal of Materials Science: Materials in Electronics - Fe3N/Fe soft magnetic composites (SMCs) are a kind of promising materials with excellent magnetic properties. In this work, Fe3N/Fe...     

Effects of Os inserted layers on the microstructures and magnetic properties of the FePt films

The microstructure and magnetic properties of multilayer [Os(t)/FePt(x)]n films on a glass substrate with a 10 nm Os buffer layer by ion beam sputtering have been studied as a function of the annealing temperatures between 300 and 800 degrees C. Here, t = 0.2, 1 or 5 nm and x varied from 10, 20, 25, 50, to 100 nm with its associated n value of 10, 5, 4, 2, and 1, respectively. No diffusion evidence was found in samples with a thin Os layer and t > or = 1 nm. The average grain size of the multilayer films can be well controlled by both annealing temperature and thickness of the FePt layer by a very thin Os space layer with t > or = 1 nm. The enhancement of H(c) can be understood from the fact that for a FePt film with an Os spacer layers, the increasing number of Os layer will inhibit the grain growth of FePt grains and enriches the grain boundary. We have experimentally demonstrated that even with a very thin 1 nm Os spacer layers, the [Os(t)/FePt(x)]n multilayer films can exhibit good hard magnetic properties and are attractive candidates for ultrahigh density magnetic recording media.     

Effects of Al content on structure and mechanical properties of hot-rolled ZrTiAlV alloys

Zirconium alloys show attractive properties for astronautic applications where the most important factors are anti-irradiation, corrosion resistance, anti-oxidant, very good strength-to-weight ratio. The effects of Al content (2.2–6.9 wt%) on structure and mechanical properties of the hot-rolled ZrTiAlV alloy samples were investigated in this study. Each sample of the hot-rolled ZrTiAlV alloys with Al contents from 2.2 wt% to 5.6 wt% is composed of the α phase and β phase, meanwhile, the relative content of the α phase increased with the Al content. However, the (ZrTi)₃Al intermetallic compound was observed as the Al content increased to 6.9 wt%. Changes of phase compositions and structure with Al content distinctly affected mechanical properties of ZrTiAlV alloys. Yield strength of the alloy with 2.2 wt% Al is below 200 MPa. As Al content increased to 5.6 wt%, the yield strength, tensile strength and elongation of the examined alloy are 1088 MPa, 1256 MPa and 8%, respectively. As Al content further increased to 6.9 wt%, a rapid decrease in ductility was observed as soon as the (ZrTi)₃Al intermetallic compound precipitated. Results show that the ZrTiAlV alloys with Al contents between 3.3 wt% and 5.6 wt% have excellent mechanical properties.     

旋转磁场对Pb-Sn-Sb合金组织及性能的影响

为了改善Pb-Sn-Sb三元轴承合金液态成型过程中的比重偏析,用旋转磁场控制Pb-Sn-Sb合金液态成型过程.采用光学显微镜、扫描电镜能谱分析研究了旋转磁场对Pb-Sn-Sb合金显微组织及成分分布的影响.用布氏硬度计、摩擦磨损试验机测试Pb-Sn-Sb合金的硬度及摩擦磨损性能.实验结果表明:旋转磁场能有效改善Pb-Sn-Sb合金的比重偏析,且能细化晶粒.激磁电压为45V时,SbSn块状化合物在试样上下截面分布最均匀,块度变小,比重偏析改善效果最好;试样上下截面Pb、Sn、Sb三元素含量基本趋于一致.随着激磁电压增加,试样上下截面的硬度及耐磨性有一定程度提高,并明显趋于一致.     

Effects of borosilicate glass additions on microstructures and magnetic properties of low temperature co-fired NiCuZn ferrites

The low temperature co-fired NiCuZn ferrites with different borosilicate glass additions are prepared by a conventional solid-state reaction method. It is found that borosilicate glass additions can enhance densification of specimens based on liquid phase sintering and grain growth promotion. Small amount of borosilicate glass additions do not have a significant effect on forming into the main phase. But too much glass additions will damage the magnetic properties. As the borosilicate glass additions increase from 0 to 0.1 wt%, the permeability measured at 100 kHz decreases from 664 to 555, while the permeability values decrease rapidly from 310 to 169 with the glass additions rising from 0.3 to 0.9 wt%. The 0.1 wt% borosilicate glass can enhance the resistivity from 4.07 × 10¹⁰ Ω cm to 9.81 × 10¹⁰ Ω cm, while 0.9 wt% borosilicate glass addition leads to inhomogeneous grains and intragranular pores, resulting in deterioration of the resistivity to only 1.4 × 10¹⁰ Ω cm.     

The role of P content on the glass-forming ability and the magnetic properties of FeSiBPC amorphous alloys

Journal of Materials Science: Materials in Electronics - The effect of P content on the glass-forming ability (GFA) and soft magnetic properties of Fe83Si5?xB11PxC1 (x?=?0, 1, 2,...