Ni、Si元素配比对Cu-Cr-Zr合金组织与性能的影响

在Cu-Cr-Zr合金中添加Ni、Si元素,制备Cu-0.6Cr-0.15Zr、Cu-2.8Ni-0.7Si-0.6Cr-0.15Zr(w(Ni)/w(Si)=4∶1)、Cu-2.8Ni-0.9Si-0.6Cr-0.15Zr(w(Ni)/w(Si)4∶1)、Cu-2.8Ni-0.56Si-0.6Cr-0.15Zr(w(Ni)/w(Si)4∶1)共4种合金。研究了Ni、Si元素及其配比对合金组织及性能的影响。结果表明:Ni、Si元素细化了合金组织,增强了合金高温力学性能。合金时效初期先析出CrSi2化合物,时效后期析出相颗粒主要有CrSi2、Ni2Si、ZrCrSi2,形态为长条形、椭圆形及圆盘状。时效处理后,与Cu-0.6Cr-0.15Zr合金相比,加入Ni、Si元素后合金硬度从131HV上升到240HV以上;导电率从88%IACS左右降到40%IACS左右。Ni、Si元素配比对导电率的峰值影响有限,在4%IACS~9%IACS;对硬度峰值的影响在20HV~30HV之间。     

High strength Al–Zn–Mg–Cu–Ni–Si alloy with improved casting properties

Abstract

The casting properties of high strength Al-7Zn-7Mg-1Cu-3Ni-3Si(wt-%) alloy are described. Compared with common Al-Zn-Mg-Cu alloys, an improvement of casting properties has been achieved by adding elements (Ni, Mg, Si) that form eutectic phases, thus reducing the solidification interval of the alloy. A comparison of thermal cooling curves, castability and hot tearing tendency has been carried out for three alloys: Al-7Zn-2Mg-1Cu (structure consists mainly of solid solution), quasi-ternary eutectic alloy Al-7Zn-7Mg-1Cu-3Ni-3Si and the common casting alloy Al-10Si. In addition, the effect of melt protection against oxidation on castability has been evaluated. It is shown that the casting properties of the protected quasi-ternary eutectic alloy are significantly better than those of the common Al-7Zn-2Mg-1Cu alloy and that they achieve a level close to that of Al-10Si alloy.     

Investigation on compressive behavior of Cu-35Ni-15Al alloy at high temperatures

Microstructures and mechanical properties of Cu-35Ni-15Al alloy in cast and porous states were studied by scanning electron microscopy and compression tests. The influence of porosity, deformation temperature and loading rate on mechanical properties of the two kinds of alloys was investigated. The results show that the as cast alloy and porous alloys have almost the same phase constitution: Cu rich phase, Ni rich phase and K intermetallics. The yield strength of porous alloys increases continuously with decreasing porosity, the relationship between porosity and yield stress follows Gibson-Ashby equation. With decreasing deformation temperature, the yield strength of as cast alloy and porous alloy increase. With the increase of loading rate, the yield strength of these alloys shows an increasing trend. After compression, the microstructure of as cast alloy is more uniform, and porous alloys are more prone to have localized deformations.     

Precipitation hardening and recrystallization in Cu-4% to 7% Ni-3% Al alloys

The effects of microstructure on mechanical properties in three cold-worked Cu-4% to 7% Ni-3% Al alloys have been investigated by changing ageing time at 500 °C. Hardness and strength in the Cu-7% Ni-3% Al and Cu-5.5% Ni-3% Al alloys increase with ageing time and have maximum values at an ageing time of 10³–10⁴s at 500 °C, then decrease. During ageing of Cu-7% Ni-3% Al at 500 °C, the coherent Ni₃Al phase was first precipitated out and later incoherent NiAl phase was formed. Ni₃Al formed during the initial stage of ageing is likely to be a transient phase. The increases in hardness and strength are due to the precipitation of coherent Ni₃Al phase. Coherent Ni₃Al particles are effective in increasing the strength and retarding the recrystallization process. On the other hand, the hardness and strength in the Cu-4% Ni-3% Al alloy gradually declined with ageing time. Only incoherent NiAl phase was formed during ageing at 500 °C. Decreases in hardness and strength in the Cu-4% Ni-3% Al alloy are attributed to softening during recovery and recrystallization, because incoherent NiAl particles have an insufficient effect to increase the strength.     

添加银对大变形Cu-14Fe原位复合材料性能的影响

成分为Cu-14Fe合金及Cu-14Fe-0.1Ag合金经熔炼后,经拉拔成变形量为4,6,7,8的线材,随后进行了时间为1h的等温时效,在此基础上测试了合金的拉伸力学性能和电导率,用金相和扫描电子显微分析研究了不同处理态合金的微观组织结构及其变化.结果表明,添加银后,合金的强度和电导率均略有提高,且经合适的等温时效工艺...     

Passivity,pitting and corrosion of anodically polarized Fe-Ni alloys in 0.5 M H2SO4 containing Cl−

Iron-nickel alloys containing 0, 20, 40, 60, 80 and 100% Ni (wt%) have been anodically polarized in 0.5 M H₂SO₄ containing Cl^?, and the conditions for passivity, pitting and corrosion with respect to alloy composition and Cl^? concentration broadly defined. Breaks occur in the values of the corrosion properties at about 30% and 70% Ni. It is considered that the corrosion properties of alloys containing up to 30% Ni are determined by the ferrite in the alloy and the low corrosion resistance of its surface film, that alloys containing 30 to 70% Ni have a corrosion resistant film probably similar to a nickel ferrite spinel, and that alloys containing over 70% Ni have properties similar to nickel and probably have a surface film based on a solid solution of iron in NiO.     

Comparative study of spinodal decomposition in symmetric and asymmetric Cu-Ni-Cr alloys

Spinodal decomposition in three alloys of nominal compositions 71Cu-27Ni-2Cr, 45Cu-45Ni-10Cr and 33Cu-52Ni-15Cr were studied by X-ray diffraction technique and transmission electron microscopy. It was found that the first and third alloys are asymmetric in nature while the second is symmetric. The symmetric alloy was found to decompose faster than the asymmetric ones. The asymmetry of the side bands was found to be related to the proportion of phases in the alloy. Electron microscopic studies revealed that during coarsening the major phase increases its connectivity by isolating the minor phase.     

Phase transformation behaviours and shape memory characteristics of Ti-45xNi-5Cu-xMo x=0.3-1.0 alloys

Abstract

Transformation behaviours and shape memory characteristics in Ti-45xNi-5Cu-xMo x=0.3, 0.5, or 1.0 at.- alloys were investigated by means of electrical resistivity measurements, differential scanning calorimetry, X-ray diffraction, thermal cycling tests under constant load, and tensile tests. The two stage transformation B2-B19-B19 occurred in Ti-45xNi-5Cu-xMo alloys, and complete separation of the B2-B19 transformation from the B19-B19 transformation was observed in Ti-44.0Mo-5Cu-1.0Mo at.- alloy. Substitution of Mo for Ni in Ti-45Ni-5Cu at.- alloy increased the critical stress for slip deformation and the pseudoelastic recovery. The maximum recoverable elongations of Ti-44.7Ni-5Cu-0.3Mo at.- and Ti-44.5Ni-5Cu-0.5Mo at.- alloys were 6.4 and 7 respectively.     

Mechanical properties and microstructures of new Ti–Fe–Ta and Ti–Fe–Ta–Zr system alloys

β-type titanium alloys consisting of non-toxic elements, Ti–8Fe–8Ta, Ti–8Fe–8Ta–4Zr, and Ti–10Fe–10Ta–4Zr, were newly designed and developed for biomedical applications. Changes in the mechanical properties of the designed alloys with various heat treatments were discussed on the basis of the resultant microstructures. In addition, the corrosion resistance of the designed alloys was evaluated by polarization testing in Hank's solution. Conventional biomedical titanium (cp-Ti) and the titanium alloy Ti–6Al–4V ELI were also polarized for comparison.The structural phase of the designed alloys, after cold rolling and solution treatment, was only the β phase. Ultimate tensile strength and elongation to fracture of Ti–8Fe–8Ta, Ti–8Fe–8Ta–4Zr, and Ti–10Fe–10Ta–4Zr after solution treatment were 1066 MPa and 10%, 1051 MPa and 10%, and 1092 MPa and 6%, respectively. Ti–8Fe–8Ta and Ti–8Fe–8Ta–4Zr have higher strength than those of conventional biomedical titanium alloys such as Ti–6Al–4V ELI, Ti–6Al–7Nb, and Ti–13Nb–13Zr. In particular, the elongations at failure of Ti–8Fe–8Ta and Ti–8Fe–8Ta–4Zr were equal to those of Ti–6Al–4V ELI and Ti–6Al–7Nb. The designed alloys and conventional biomedical titanium alloys were spontaneously passivated in Hank's solution. The current density of cp-Ti and Ti–6Al–4V ELI was increased at a potential above 2.5 V. On the other hand, the current density of the designed alloys abruptly increased at a potential above 3.5 V. The designed alloys have the advantage over cp-Ti and Ti–6Al–4V ELI in their high resistance to pitting corrosion in biological environments.Therefore, new β-type titanium alloys designed in this study, Ti–8Fe–8Ta and Ti–8Fe–8Ta–4Zr, are expected to have good properties as biomaterials.     

Microstructural Changes of Cu-Ni-Si Alloy during Aging

Age hardening in Cu-3.2Ni-0.75Si (wt pct) and Cu-1.0Ni-0.25Si (wt pct) alloys from 723 to 823 K is studied. After an incubation period strengthening appears which is due to precipitates in the Cu-l.ONi-0.25Si (wt pct) alloy. On other hand an immediate increase of the yield strength characterizes the aging of the alloy. This is followed by the regions of constant yield strength and further by a peak. The microstructure of the alloy was studied by, means of transmission electron microscope (TEM) and X-ray diffraction (XRD). Spinodal decomposition takes place followed by nucleation of the ordering coherent (Cu,Ni)3Si particles, further precipitation annealing coherent δ-Ni2Si nucleated within the (Cu,Ni)3Si particle. Any change of the yield strength can be described by an adequate change of the structure in the sample. The nature of the aging curves with a "plateau" is discussed. The formulas of Ashby and Labusch can be used to explain the precipitation.     

杂质元素对镁合金组织与性能的影响及其对应措施

镁及镁合金中杂质元素的含量及作用已受到广泛关注.介绍了镁合金中Fe、Cu、Ni、Si等杂质的存在形式,综述了杂质元素对镁合金显微组织、腐蚀性能、力学性能的影响规律及机制,并叙述了几种提高镁合金纯度常见的方法,包括选用高纯原料、优化熔炼工艺、镁合金熔体纯净化,指出有效降低杂质含量将是未来高性能镁合金材料研究的重要方向.     

不同Cr含量的Ni基合金电化学腐蚀行为

利用电化学测试技术研究不同Cr含量的Ni基合金耐Cl-离子水溶液腐蚀的能力。结果表明：Ni基合金耐Cr离子腐蚀性能随着合金中Cr含量的提高而增强,溶液中Cl-离子浓度对Ni-9Cr、Ni-15Cr和Ni-20Cr合金有较大影响,特别是Ni-9Cr合金在0．6mol／LNaCl溶液中腐蚀最为严重,而对于Ni-25Cr和N...     

A study of spinodal decomposition in Ni-30 at% Cu and Cu-46 at% Ni-4 at% Fe alloys using electrical resistivity measurements

The spinodal decomposition in Ni 30 at% Cu and Cu-46 at% Ni-4 at% Fe alloys has been investigated using electrical resistivity measurements. The electrical resistivity results, for ageing temperatures between 423 and 823 K, were analysed from the equation of change of electrical resistivity for spinodal decomposition in binary alloys proposed by Kolometz and Smirnov, together with the classical spinodal decomposition theory of Cahn. This analysis enabled us to obtain a plot of the amplification factor, R(), as a function of temperature. From this plot, the coherent spinodal temperatures for Ni-30 at% Cu and Cu-46 at% Ni-4 at% Fe alloys were found at 590 and 790 K, respectively, and are in good agreement with experimental and theoretical values reported by other authors.     

Effects of Solid Solution Treating on the Microstructureand Damping Behaviour of MnCuNiFe Alloys

A high damping condition is easily obtained in Mn-(16~24)Cu-(4~6)Ni-2Fe (at. pct) alloys,when cooling rate is controlled after the solid solution treatment at 1173 K. It is observed that the temperature dependent changes of Iogarithmic decrement in 10 h cooled samples are sensitive to the alloy composition. As compared with water quenching treatment, controlled 10 h cooling improves TN temperature of the alloys extensively by producing a Mn-enriched matrix portion in the alloys. Calcuiations suggest that the relative decreases of Cu and Ni content in the matrix portion be dominated by the Ni content in the original alloys, and therefore, the volume fraction of the Cu, Ni-enriched precipitates is estimated to be about 20% and 10% in the 4Ni and 6Ni alloys, respectively. As a result, the TN temperature fOr each alloy, corresponding to the rising temperature of logarithmic decrement, has been related to the Cu, and Ni content in the Mnenriched matrix. The existence of {110} twinning boundaries is confirmed in the microstructure of both 4Ni and 6Ni alloys. However, the relative lattice strains, which the twinning boundaries act to accommodate, are found largely different in the two alloys. It is considered that boundaries with smaller orientation deviation could coordinate the external Stresses easily by cyclic moving, and therefore, the broader damping peak which occurs in the 10 h cooled 6Ni alloy becomes feasible. Electron diffraction results also indicate possible for mation of many sub-crystals in the matrix phase, which are relatively rotated on some invariant planes. Those sub-crystal boundaries might play some attenuation roles in the temperature range between TN and room temperature.     

A study on dental nonprecious cast alloys

The ternary nickel-copper-manganese (Ni-Cu-Mn) cast alloys were studied on hardening by the addition of elements such as aluminium and indium to the ternary alloys. Tensile tests showed that both the 20 Ni-40 Cu-40 Mn (which has the lowest melting temperature of all the Ni-Cu-Mn ternary alloys investigated) and the 50 Ni-30 Cu-20 Mn (with the highest melting temperature) exhibited a ductile behaviour. Dendritic structures seen by optical microscopy were constituted of ternary alloys containing aluminium and indium and the amount of dendritic structures increased in the indium-containing alloys rather than in the aluminium containing alloys, and as a result the hardness (VHN) had larger values in the latter alloy than in the former alloy.     

Cold worked Cu-Fe-Cr alloys

The aim of this project was to investigate the properties of copper rich Cu-Fe-Cr alloys for the purpose of developing a new cost effective, high-strength, high-conductivity copper alloy. This paper reports on the influence of cold work. The age hardening response of the Cu-0.7%Cr-2.0%Fe alloy was minimal, but the resistance to softening was superior to that reported for any commercial high-strength, high-conductivity (HSHC) copper alloy with comparable mechanical and electrical properties. For example, an excess of 85% of the original hardness of the 40% cold worked alloy is retained after holding at 700°C for 1 hour, whereas commercial HSHC Cu-Fe-P alloys have been reported to soften significantly after 1 hours exposure at less than 500°C. The Cu-0.7Cr-2.0Fe alloy would therefore be expected to be more suitable for applications with a significant risk of exposure to elevated temperatures. Optical microscope examination of cold worked and aged microstructures confirmed the high resistance to recrystallization for Cu-0.7%Cr-2.0%Fe. The Zener-Smith drag term, predicting the pinning effect of second phase particles on dislocations in cold worked microstructures, was calculated using the precipitate characteristics obtained from TEM, WDS and resistivity measurements. The pinning effect of the precipitate dispersions in the peak-aged condition was determined to be essentially equivalent for the Cu-0.7%Cr-0.3%Fe and Cu-0.7%Cr-2.0%Fe alloys. A lower recrystallisation temperature in the Cu-0.7%Cr-0.3%Fe alloy was therefore attributed to faster coarsening kinetics of the secondary precipitates resulting from a higher Cr concentration in the precipitates at lower iron content.     

Fe和Ce 含量对Galfan合金力学性能及耐蚀性的影响

将真空熔炼的Zn-Fe-Ce中间合金加入到Zn-Al熔池中,制备Zn-5Al-0.1Ce-xFe和Zn-5Al-yCe-0.1Fe合金,分析了Fe和Ce含量对合金显微组织及力学性能的影响,并使用电化学工作站测试了合金的电化学性能。结果表明,在Zn-5Al-0.1Ce合金中Fe含量大于0.02%后会形成颗粒状的FeAl3Znx相。随着Fe含量的增加,FeAl3Znx相和先共晶的η-Zn相增加,Zn-Al共晶组织由层片状向点状转变。添加0.1%以下的Fe可提高Galfan合金的抗拉强度。但随着Fe含量的增加,合金的抗拉强度略有降低,Zn-5Al-0.1Ce-0.02Fe合金的综合力学性能最好。添加0.04%以下的Fe会提升合金耐蚀性。此外,随着Ce含量的增加,Zn-5Al-yCe-0.1Fe合金的抗拉强度有所降低,耐蚀性变化不明显。因此,在生产中需要根据镀层性能要求,严格控制合金液中的Fe和Ce含量。     

Effect of carbon on mechanical properties of powder-processed Fe-0.35%P alloys

The present paper records the results of mechanical tests on iron-phosphorus powder alloys which were made using a hot powder forging technique. In this process mild steel encapsulated powders were hot forged into slabs, hot rolled and annealed to relieve the residual stresses. These alloys were characterized in terms of microstructure, porosity content/densification, hardness and tensile properties. Densification as high as 98.9% of theoretical density, has been realized. Microstructures of these alloys consist of single-phase ferrite only. Alloys containing 0.35 wt% P, such as Fe-0.35P-2Cu-2Ni-1Si-0.5Mo and Fe-0.35P-2Cu-2Ni-1Si-0.5Mo-0.15C show very high strength. It was observed in this present investigation that, the alloying additions, such as Si, Mo, Ni, and C to Fe-P based alloys caused increase in strength along with reduction in ductility. Cu reduces porosity of Fe-P alloys. Alloys developed in the present investigation were capable of hot working to very thin gauge of sheets and wires.     

Enhancing mechanical properties and corrosion resistance of nickel-aluminum bronze via hot rolling process

The mechanical properties and corrosion behavior of as-cast, as-annealed and hot-rolled nickelaluminum bronze(NAB) alloy(Cu-9 Al-10 Ni-4 Fe-1.2 Mn, all in wt.%) in 3.5 wt.% Na Cl solution were investigated. The results show that annealing introduces a large number of k phases to precipitate in the k phase. However, after further hot rolling, the original continuous k phases are spheroidized and dispersed, increasing the strength, hardness, and elongation of the alloy. In addition to the enhanced mechanical properties, the corrosion resistance of the NAB samples is also improved significantly by hot rolling, as revealed by the mass loss measurements, electrochemical impedance spectroscopy(EIS), and cross-sectional corrosion morphology. Selective phase corrosion occurs by the preferential corrosion of the k phase, which acts as an anode to the k phases, and the uncorroded k phases are retained in the corrosion product film. The interfaces between the k phases and the surrounding corrosion products become discontinuous caused by the spheroidization of k phases, reducing the corrosion of the substrate by the corrosive medium via the channels. As a result, the corrosion rate and the maximum local corrosion depth of the hot-rolled NAB sample are greatly reduced.     

Microstructure evolution and mechanical property of Cu-15Ni-8Sn-0.2Nb alloy during aging treatment

Aging treatment of Cu-based alloys is essential to enhance their strength that is desirable for their exten-sive engineering applications in electrical industry,whereas the underlying mechanism of strengthening is essential for massive manufacturing of these alloys.Here,the microstructure evolution of a supersatu-rated solid solution Cu-15Ni-8Sn-0.2Nb alloy aged at 400℃for different time was characterized at atomic scale using state-of-the-art transmission electron microscopy(TEM)and the corresponding mechanical property was also measured.The results reveal that the modulated structure,DO22/L12 ordering,and discontinuous precipitation(DP)appeared in the advances of aging time.At the early stage of aging treatment,component modulation waves and satellite spots appeared from spinodal decomposition and the modulation wavelength was identified in the range of 1-7 nm.Subsequently the modulated struc-tures formed-poor-rich solute regions,of which DO22 ordering was present in the Ni-poor region while L1 2 ordering appeared in the Ni-rich region.The sequence of ordering precipitates was further verified by density functional theory(DFT)simulations.Furthermore,orientation relationships and interfacial structures between DO22,L12 phases and the parent matrix were determined.The measured hardness of alloy reached a maximum value of 335 HV after aging for 120 min due to the coherence between the two ordering phases and matrix.These results illustrated the importance of aging on structural evolution and mechanical property of Cu-15Ni-8Sn alloy at various heat treatment stages,which could potentially help in manufacturing promising alloys for their extensive engineering applications.