一种非晶增强铝基复合材料的制备工艺及组织性能

利用搅拌摩擦加工技术成功制备了一种新型非晶增强铝基复合材料,分析其显微组织、硬度以及元素成分分布.试验结果表明,复合材料主要由母材和非晶带交替形成的层状结构组成,显微硬度有明显提高.复合材料中的非晶带产生了一定的晶化,摩擦热、机械搅拌力以及轴肩压力的综合作用可能是导致非晶带晶化的主要原因.     

非铁金属的焊接

利用搅拌摩擦加工技术成功制备了一种新型非晶增强铝基复合材料．分析其显微组织、硬度以及元素成分分布。试验结果表明,复合材料主要由母材和非晶带交替形成的层状结构组成,显微硬度有明显提高。复合材料中的非晶带产生了一定的晶化,摩擦热、机械搅拌力以及轴肩压力的综合作用可能是导致非晶带晶化的主要原因。图3表3参11     

非铁金属的焊接

利用搅拌摩擦加工技术成功制备了一种新型非晶增强铝基复合材料．分析其显微组织、硬度以及元素成分分布。试验结果表明,复合材料主要由母材和非晶带交替形成的层状结构组成,显微硬度有明显提高。复合材料中的非晶带产生了一定的晶化,摩擦热、机械搅拌力以及轴肩压力的综合作用可能是导致非晶带晶化的主要原因。图3表3参11     

采用FSP制备新型非晶增强铝基复合材料的组织与性能

利用搅拌摩擦加工技术获得的新型非晶增强铝基复合材料,通过金相、扫描电镜、显微硬度及拉伸试验等对其显微组织结构及力学性能进行了试验和分析.试验结果表明,复合材料主要以层状结构组成,主要由母材和非晶带交替形成.复合材料显微硬度明显高于母材,并且复合材料的抗拉强度显著提高,当旋转速度达到750 r/min,抗拉强度达到最大值...     

AZ31B镁合金表面激光熔敷+搅拌摩擦加工改性层结构与性能

采用激光熔敷和搅拌摩擦加工相结合的方法在AZ31B镁合金表面分别制备了Cu+Al和Si+Al改性层。通过SEM、XRD、显微硬度测试以及电化学腐蚀对表面改性层的微观组织、相组成、显微硬度及耐腐蚀等性能进行分析。结果表明,用Cu+Al和Si+Al粉末制备的改性层化合物分别主要由β-Al_(12)Mg_(17)及少量的Al Cu_4、Al Mg和Mg_2Si、Al Mg及少量的β-Al_(12)Mg_(17)组成。搅拌摩擦加工改性层与镁合金基体结合良好,表面平整光滑、组织均匀细小。与镁合金基体相比,表面改性层的显微硬度和耐腐蚀性能均得到明显提高,经搅拌摩擦加工之后的添加Si+Al混合粉末改性层的HV显微硬度值最高可达2.96 GPa,比母材提高了385.3%;添加Cu+Al混合粉末改性层的自腐蚀电位最高可达–0.975 V,比母材提高了37.4%。     

水下搅拌摩擦加工纯铜及其合金的显微组织演变和摩擦性能（英文）

对工业纯铜(纯度99.8%)和铜锌合金(黄铜)进行水下搅拌摩擦加工。搅拌摩擦加工的刀具呈螺纹锥状,由碳化钨制成,其转速为1800 r/min,横移速度为4 mm/min,将试样浸泡在带循环系统的水箱中。为了评估加工次数对样品显微组织和力学性能的影响,进行6道次加工。采用光学显微镜对商业纯铜样品的显微组织进行研究,结果表明,加工后材料的晶粒尺寸明显减小。同时,样品横截面的硬度较母材增高。水下搅拌摩擦加工样品的X射线衍射谱与母金属的相比,其峰值更短、更宽,谱的背景增大,表明形成非晶/超细晶组织。采用针-盘法对试样的磨损行为进行研究,结果表明,与母材相比,加工后试样的摩擦因数降低。磨损和硬度试验结果表明,水下搅拌摩擦加工可显著提高工业纯铜和黄铜的耐磨性和硬度。     

FSW中搅拌速度对非晶复合材料结构和硬度的影响

通过铜模吸铸法制备了尺寸为60mm×20mm×2.5mm的非晶复合材料板材。对非晶复合材料板材预热后,进行搅拌摩擦焊连接。在焊接速度为20mm/min和下压量为0.2mm的情况下,研究搅拌头旋转速度对非晶复合材料显微结构和显微硬度的影响。结果表明,非晶复合材料板材在焊接后,搅拌区晶化相尺寸比铸态有不同程度的减小。在搅拌头旋转速度低于1 000r/min时,转速越高,晶化相尺寸越小;在搅拌头旋转速度大于1 000r/min时,热作用加剧,晶化相开始粗化。显微硬度测试表明,焊接后试样搅拌区的硬度均比铸态低。其中,搅拌头旋转速度为1 000r/min时的硬度略高于800r/min时的硬度,而在1 200r/min时,硬度最低。     

采用搅拌摩擦焊方法制备的非晶增强铝基复合材料的微观组织分析

利用金相、EDS、XRD及TEM试验等对采用源于搅拌摩擦焊方法的搅拌摩擦加工技术制备的非晶增强铝基复合材料的微观组织结构进行试验分析.结果表明,非晶增强体与基体5A06铝合金经过搅拌摩擦加工过程充分的搅拌作用,获得了层状混和组织结构.复合材料中存在大量的90~400 nm纳米级组织,主要由-αA l与-αA l非晶组织构成.纳米级组织的存在有助于复合材料性能的提高,而非晶结构的存在表明非晶增强体在搅拌摩擦加工过程中并未完全晶化.     

AZ31B镁合金表面激光熔敷 搅拌摩擦加工改性层结构与性能研究

采用激光熔敷和搅拌摩擦加工技术相结合的方法对AZ31B镁合金表面分别制备了Cu Al和Si Al改性层。通过SEM、XRD、显微硬度以及电化学腐蚀测试系统对表面改性层的微观组织、相组成及耐腐蚀等性能进行分析测试。用Cu Al和Si Al粉末分别制备的改性层化合物主要由β-Al₁₂Mg₁₇及少量的AlCu₄、AlMg和Mg₂Si、AlMg及少量的β-Al₁₂Mg₁₇组成。搅拌摩擦加工改性层与镁合金基体结合良好,表面平整光滑、组织均匀细小。与镁合金基体相比,表面改性层的显微硬度和耐腐蚀性能均得到明显提高,经搅拌摩擦加工之后的添加Si Al混合粉末改性层的显微硬度值最高可达296 HV,比母材提高了385.3%;添加Cu Al混合粉末改性层的自腐蚀电位最高可达-0.975 V,比母材也提高了37.4%。     

水下搅拌摩擦加工制备CoCrFeNiMn/6061Al复合材料组织和性能研究

采用水下搅拌摩擦加工制备CoCrFeNiMn高熵合金颗粒增强6061-T6基复合材料，研究了时效热处理对CoCrFeNiMn/6061Al复合材料微观组织、显微硬度和磨损性能的影响。采用扫描电镜和电子背散射衍射技术对复合材料的微观组织进行了表征，采用显微硬度和磨损实验对复合材料的性能进行了评价。结果表明，经5道次搅拌摩擦加工后，CoCrFeNiMn高熵合金颗粒均匀分布在Al基体中，且与基体界面结合良好，无明显扩散层。时效热处理后，CoCrFeNiMn高熵合金颗粒与基体界面出现厚度约为200 nm的扩散层，复合材料的平均显微硬度达到120.0 HV,比Al基体提高了27.7%。与Al基体相比，复合材料的平均摩擦因数从0.4491升高至0.4855。时效热处理后，复合材料的平均摩擦因数降低至0.3188,主要磨损机制为磨粒磨损。     

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.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.     

Theoretical Analysis for the Motion and Temperature of Melt Droplets in Spray Degassing Process

The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results.     

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.