新型Cu-Fe-C复相合金的制备及其变形行为

采用真空熔炼和快速凝固方法制备了组织优异的新型Cu-Fe-C复相合金,并通过金相、SEM、TEM、XRD以及力学性能测量分别对复相合金铸态和冷轧态显微组织变化和变形行为进行了研究。结果表明,当凝固界面推移速率满足VcVVp时,微米级和纳米级的Fe-C相可均匀弥散分布于合金基体内,不过微米级Fe-C粒子对应的此速率范围远小于纳米级Fe-C粒子的;由于溶质元素Fe在Cu基体内的固溶和不同尺寸Fe-C相的存在,使得熔铸态复相合金具有较高的加工硬化率(n=0.3628);80%冷轧变形可诱发合金基体内的Fe-C相发生γ-Fe→α-Fe相变,充分利用这一相变可用于调控Cu-Fe-C复相合金的强度和加工变形性能;虽然熔铸态和冷轧态合金均具有较好的协调变形性能,但是相比而言,Fe-C相处于FCC结构时的熔铸态合金可表现出更好的协调变形行为;此外,本文根据复相铜合金的组织演化以及拉伸断口形貌提出了该类合金协调变形和断裂模型示意图。     

新型Cu-Fe-C复相合金的制备及其变形行为的研究

本文采用真空熔炼和快速凝固方法制备了组织优异的新型Cu-Fe-C复相合金,并通过金相、SEM、TEM、XRD以及力学性能测量分别对复相合金铸态和冷轧态显微组织变化和变形行为进行了研究。结果表明,当凝固界面推移速率满足V_cp时,微米级和纳米级的Fe-C相可均匀弥散分布于合金基体内,不过微米级Fe-C粒子对应的此速率范围远小于纳米级Fe-C粒子的;由于溶质元素Fe在Cu基体内的固溶和不同尺寸Fe-C相的存在,使得熔铸态复相合金具有较高的加工硬化率(n=0.5149);80%冷轧变形可诱发合金基体内的Fe-C相发生γ-Fe→α-Fe相变,充分利用这一相变可用于调控Cu-Fe-C复相合金的强度和加工变形性能;虽然熔铸态和冷轧态合金均具有较好的协调变形性能,但是相比而言,Fe-C相处于FCC结构时的熔铸态合金可表现出更好的协调变形行为;此外,本文根据复相铜合金的组织演化以及拉伸断口形貌提出了该类合金协调变形和断裂模型示意图。     

冷轧变形量对传感器用固溶态BT22钛合金板组织及拉伸性能的影响

为了提高传感器基板用BT22钛合金板的力学性能,先通过850℃+0.5 h固溶处理,然后通过冷轧的方式对其进行加强。通过实验测试手段研究冷轧变形量对固溶态BT22钛合金板的组织及拉伸性能的影响。研究结果表明:综合运用高冷轧变形量与较低再结晶温度有助于BT22钛合金板发生再结晶时形成更多细小尺寸的晶粒。轧制后BT22钛合金板的强度比轧制之前的强度有了较大的提升,强度至少提高200 MPa。随着冷轧变形量的增加,合金强度不断增加,但增加幅度减小。冷轧后合金的伸长率虽有所下降,但依然可以保持在10%以上。冷轧变形后合金的最高屈服强度在冷轧变形量为80%时取得,此时合金的屈服强度为1012 MPa,抗拉强度为1042 MPa,伸长率为10%。     

锻态Ti-44Al-4Nb-4V-0.3Mo-Y合金等轴及片层组织高温拉伸性能及组织演变

等轴γ晶粒和α2/γ片层是beta-gamma TiAl合金的2种主要变形组织形态。研究了锻态Ti-44Al-4Nb-4V-0.3Mo-Y合金等轴组织及片层组织的高温拉伸性能及组织演变。结果表明:拉伸温度对Ti-44Al-4Nb-4V-0.3Mo-Y合金的力学性能和显微组织有显著的影响。在相同温度下,Ti-44Al-4Nb-4V-0.3Mo-Y合金等轴组织的抗拉强度和屈服强度略高于片层组织,而延伸率相差不大。随拉伸温度的升高,合金的抗拉强度和屈服强度逐渐减小,而延伸率迅速增大。对于等轴组织,提高温度,等轴γ晶粒被拉长,发生完全的动态再结晶,从而细化合金的显微组织。对于片层组织,α2/γ片层的分解和γ板条的再结晶程度随拉伸温度的升高而增大。Ti-44Al-4Nb-4V-0.3Mo-Y合金的韧脆转变温度在750～800℃之间。     

热处理对NiW中/重合金组织与性能的影响

本文研究了不同热处理温度对冷轧态Ni42W10Co1Mo合金微观组织及力学性能的影响规律。结果表明,随着热处理温度的升高,合金中TCP相由σ相向μ相转变,μ相再向σ相转变,基体组织由条带状变形组织逐渐转变为均匀的等轴晶。经900℃热处理,析出相主要以针状与块状μ相析出为主,同时还有少量颗粒状μ相,发生明显再结晶现象。经1200℃热处理,颗粒状σ相大量析出,基体组织完成静态再结晶过程。TCP相的析出消耗了基体中固溶强化元素W,导致合金的室温屈服强度下降,屈服强度由初始态合金的1564MPa下降至1200℃热处理后的479MPa。小尺寸的σ相能阻碍裂纹的扩展,有利于提升合金的塑性,经1200℃热处理合金延伸率达到了72.4%。然而较大尺寸的μ相对合金的塑性产生不利影响,经900℃热处理后合金延伸率仅有7.1%。     

Effects of Long-Term Aging on the Microstructures and Tensile Properties of Ni-Based Single Crystal Superalloy

利用微观分析方法研究了第二代镍基单晶合金 DD6 标准热处理和980 ℃/1050 ℃/1200 ℃/长期时效对γ/γ′形态演化和拉伸性能的影响。结果显示：镍基单晶合金DD6在较高温度时效处理后会发生形态不稳定,1050 ℃/时效800 h后γ′强化相逐渐连接成筏;1200 oC时效100 h后,γ/γ′微结构的立方度明显下降并逐渐向球形边界转化,并伴有少量细小基体相嵌入强化组织。在γ/γ′界面附近分布着大量位错线,位错运动随着时效处理时间和温度的增长而加强。1050 ℃/时效1000 h后在固溶元素富集区析出块状沉淀相,其脆性特征在低温拉伸时会塞积位错运动形成应力集中。760 ℃高温下的抗拉强度、屈服强度和延伸率随着时效时间增长而减小,断面收缩率有所波动     

长期时效对镍基单晶合金微结构演化和拉伸性能的影响（英文）

利用微观分析方法研究了第二代镍基单晶合金DD6标准热处理和980℃/1050℃/1200℃/长期时效对γ/γ′形态演化和拉伸性能的影响。结果显示:镍基单晶合金DD6在较高温度时效处理后会发生形态不稳定,1050℃/时效800 h后γ′强化相逐渐连接成筏;1200oC时效100 h后,γ/γ′微结构的立方度明显下降并逐渐向球形边界转化,并伴有少量细小基体相嵌入强化组织。在γ/γ′界面附近分布着大量位错线,位错运动随着时效处理时间和温度的增长而加强。1050℃/时效1000 h后在固溶元素富集区析出块状沉淀相,其脆性特征在低温拉伸时会塞积位错运动形成应力集中。760℃高温下的抗拉强度、屈服强度和延伸率随着时效时间增长而减小,断面收缩率有所波动。     

冷轧与退火对LA91合金显微组织和力学性能的影响

对热挤压态LA91合金进行了冷轧及退火处理,研究了不同冷轧变形量与退火温度对合金显微组织和力学性能的影响。结果表明,总轧制变形量为76.7%的LA91合金薄板具有较高的强度和良好的塑性(抗拉强度为177 MPa,伸长率为37.4%)。在200~300℃范围内退火,冷轧LA91合金发生回复和再结晶,β相逐渐变为等轴状,α相逐渐球状化。因此,随退火温度升高,合金薄板的抗拉强度先降低后升高,伸长率则先升高后降低。同一变形量下,合金中的α相再结晶温度略高于β相;经1h退火,不同变形量的冷轧LA91合金开始再结晶的温度略微不同,约为250℃,退火温度为300℃时,再结晶完成。     

新型高强度易加工Cu-FeC复合材料的变形行为

采用真空感应熔炼和快速凝固技术制备了界面复合良好,组织性能优异的新型Cu-FeC复合材料,并通过OM、SEM、TEM、XRD以及力学性能测试分别对熔铸态、奥氏体化后的淬火态及其冷轧态复合材料的组织和变形行为进行了研究。结果表明,熔铸态材料内共存有γ-Fe、α-Fe和马氏体相,而经820℃,4 min奥氏体化和淬火处理后,基体内初生Fe-C相可转化为马氏体相,同时析出大量纳米级γ-Fe相粒子;前者在冷轧过程中表现出较好的协调变形性能,而后者会在粗大Fe-C马氏体相内部或附近产生微裂纹;不过两者冷轧变形后的强度均能获得大幅提升,最高抗拉强度达515 MPa,而延伸率又明显高于已报道具有类似强度陶瓷粒子强化铜基复合材料的延伸率,且拉伸过程均表现出明显的塑性变形特征;此外,本研究根据复合材料组织演化规律提出了相应的组织演化模型图。     

高温时效对高温镍基合金沉淀强化的影响

研究了750～1050℃下长期时效对Ni3Al基高温合金沉淀强化的影响.结果表明:镍基高温合金在不同温度时效处理一定时间后,γ'沉淀强化相呈球形分散在γ基体上,随时效温度升高,γ'沉淀相微粒粗化,合金屈服强度降低,拉伸塑性提高.随着时效时间的延长,合金的屈服强度增大,但当时效时间超过1000 h之后,屈服强度和伸长率开始下降.Ni-Al合金的性能和沉淀相的颗粒大小、分布、体积分数及粗化速率等因素有关.     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

Thermodynamics Study on the Decomposition of Chromite with KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

Influence of Heat Treatment on Damping Behaviour of the Magnesium Wrought Alloy AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.     

电化学噪声数据处理方法概述

综述了常见的电化学噪声数据处理方法,介绍了直流趋势剔除、统计分析、快速傅立叶变换(FFT)法计算功率谱密度(PSD)以及小波变换处理电化学噪声信号的基本过程,并阐释了各种数学处理及所得参数的物理意义。