双重时效的低温形变热处理对Al-Mg-Si-RE合金力学性能的影响

研究了双重时效的低温形变热处理（ＬＴＨＴ）对ＡｌＭｇＳｉＲＥ合金力学性能的影响。双重时效的低温形变热处理使ＡｌＭｇＳｉＲＥ合金获得抗拉强度σｂ＝３５０ＭＰａ,σ０．２＝２９１ＭＰａ和延伸率δ＝６％的最佳综合力学性能。显然用这种处理工艺比用固溶淬火＋时效的普通热处理工艺优越。研究表明,双重时效的低温形变热处理是有效提高ＲＥＡｌ合金强度的一种值得推广的工艺。     

锶—稀土长效变质剂的应用

研究了铝－锶－稀土合金对铝硅合金中的共晶硅及亚共晶硅的细化变质作用，该变质剂变质时间可保持４小时以上下衰退，同时还具有除气和净化铝液的功能，克服了单独用锶变质时吸气及不能同时用氯化物精炼等问题，并发现了Ｓｒ与ＲＥ在变质过程中有协同效应。     

不同变质剂对ZL101合金共晶硅粒状化的影响

利用ＩＢＡＳ－１型图像分析仪，研究了不同变质剂处理的ＺＬ１０１合金在热处理时共晶硅的粒状化效果，结果表明：变质可有效地促进共晶硅的粒状化，不同的变质剂对ＺＬ１０１合金共晶硅粒状化的作用是不同的，按促进共晶硅粒状化能力的大小顺序排列为：复合变质〉Ｎａ或Ｓｒ变质≥Ｓｂ变质。     

加Sb变质对Al—Si12.7%合金共晶硅生长的影响

采用自制的连续定向凝固装置，借助ＳＥＭ和ＦＥＭ考察了在较大生长速度范围内，（Ｒ＝３０－２５００μｍ／ｓ）Ａｌ－Ｓｉ共晶的生长过程，着重考察了Ｓｂ变质元素的影响。发现加Ｓｂ变质后较未加变质剂时，硅相的微观结构特征没有明显变化，但更倾向于等温生长。其生长方式与未变质时相同。     

热处理对ZA33－3合金组织及力学性能的影响

试验了热处理工艺参数（包括固溶处理温度、时间、冷却方式、时效温度等）及几种微量元素（ＲＥ、Ｐｈ、Ｔｉ、Ｂｉ、Ｓｂ、Ｓｔ）对ＺＡ３３－３合金时效特性的影响；用Ｘ射线衍射仪及能谱分析仪对热处理过程中组织结构的变化进行了分析；找出了具有较高强度和塑性的合金组份及热处理工艺，即ＺＡ３３－３＋０．１％Ｓｂ合金、ＺＡ３３－３＋０．０１％Ｂｉ合金．绎３６５℃×３ｈ水淬＋１００℃×１．５ｈ时效处理后．其综合性能最好。     

Si在变形Ni—Cu—Fe—Mn—Si合金中的行为

研究了热处理后前后变形Ｎｉ－Ｃｕ－Ｆｅ－Ｍｎ－Ｓｉ合金中的Ｓｉ的存在形式，在晶界及晶内的分布状态和结构，并研究了在热处理状态下，合金性能的变化，ＸＲＤ分析表明：Ｎｉ－Ｃｕ－Ｆｅ－Ｍｎ－Ｓｉ合金基体为面心方立结构，在热加工状态（Ｒ态）下，Ｎｉ－Ｃｕ－Ｆｅ－Ｍｎ－Ｓｉ合金除Ｎｉ３Ｓｉ相外，还出现了Ｎｉ３１Ｓｉ１２相。该相为立方结构。ＴＥＭ分析表明：第二相（Ｎｉ３Ｓｉ）在晶界和晶内弥散分布，少量在晶界聚     

Al—Sr中间合金变质效果的遗传效应

通过不同铸工艺制取的相同成要不同形貌的变质用Ａｌ－８．６２％Ｓｒ中间合金，具有明显的变质效果差异。在砂型条件下，用Ａｌ－８．６２％Ｓｒ中间合金对共晶Ａｌ－Ｓｒ合金进行变质处理，加入使Ａｌ－Ｓｒ合金含０．１％Ｓｒ的锭料和加入使Ａｌ－Ｓｒ合金含０．０５％Ｓｒ的激冷薄片，二者的变质效果相当，都为５级。在金属型条件下，加入使Ａｌ－Ｓｒ合金含０．０６％Ｓｒ锭料和加入使Ａｌ－Ｓｉ合金含０．０３％Ｓｒ的激冷薄片     

过共晶Al—Si合金变质处理

研究了不同变质剂Ｐ、Ｓ、ＲＥ以及Ｐ与Ｓ、Ｐ与ＲＥ对过共晶Ａｌ－Ｓｉ合金的变质结果。结果表明：Ｐ与ＲＥ联合变质的变质效果最佳,既能细化初生硅,又能细化共晶系。     

锶－稀土长效变质剂的应用

研究了铝－锶－稀土合金对铝硅合金中的共晶硅及亚共晶硅的细化变质作用，该变质剂变质时间可保持４小时以上不衰退，同时还具有除气和净化铝液的功能，克服了单独用锶变质时吸气及不能同时用氯化物精炼等问题，并发现了Ｓｒ与ＲＥ在变质过程中有协同效应。     

热处理工艺对AlSi＆.0Mg0.3和AlSi7.0Mg0.3Sr合金组织的影响

研究了热处理工艺对定向凝固条件下Ａｌ－Ｓｉ合金共晶组织的影响。通过多级长时间的固溶处理及回火处理，ＡｓＳｉ７．０Ｍｇ０．３０和ＡｌＳｉ７．０Ｍｇ０．３Ｓｒ合金中的共晶体体积分散在较快冷却速度时要比慢速冷却时的高，而共晶体中硅粒子的体积分数则有较大幅度的降低。     

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。