非晶Al-Y-Nd-Ni合金的晶化行为

采用单辊旋淬快速凝固方法制备出Al85Y4Nd4Ni7的薄带合金，对快速凝固合金进行DSC分析和X射线衍射分析并测试了合金显微维氏硬度。结果表明：在激冷态时，合金组织为非晶与过饱和α-Al共存；在310℃退火时，非晶转变为nm级Al晶，同时出现了三元亚稳相AlNiY与AlNdNi；在340℃和400℃退火后，亚稳相并没有完全消失，只是部分地转变为二元平衡相Al3Ni和Al3Nd。材料的硬度值在310℃和340℃退火后几乎一样，都比激冷态明显提高，然而在400℃退火后，材料的硬度值却急剧下降，这是由于晶粒长大造成的.     

快速凝固Al—Ti—Fe系合金的组织演化

采用单辊旋铸技术制备Al-2.5Ti-2.5Fe,Al2.5Ti-2.5Fe-2.5V和Al-2.5Ti-2.5Fe-2.5Cr(at%，下同）合金薄带，利用X射线衍射（XRD）和透射电镜（TEM）分析了这些合金的急冷态和退火态组织。结果表明：快速凝固Al-2.5Ti-2.5Fe合金急冷态组织中存在Al3Ti和Al5Ti2两种初生相，快凝合金经400℃退火10h后，组织中出现了Al13Fe4相，在450℃退火，组织中析出了弥散Al3Ti相；快速凝固Al-2.5Ti-2.5Fe-2.5V合金急冷态组织中存在Al11V相和Al80V20相，400℃退火10h后，初生Al11V相转变为Al80V20相，且固溶在α-Al基体中的Ti,Fe以Al23Ti9相和Al13Fe4相的形式析出；快速凝固Al-2.5Ti-2.5Fe-2.5Cr合金急冷态组织中存在Al3Ti和Al13Cr2两种初生相，快凝合金经300℃退火10h后，组织中析出了Al13Cr2和Al3Ti两种弥散相，400℃退火10h时后组织中出现了Al13Fe4相。     

快速凝固Al-2.5Ti-2.5Fe合金显微组织及热稳定性的研究

采用单辊旋铸技术制备Al-2.5Ti-2.5Fe合金薄带，利用DSC分析、X射线衍射和透射电镜来分析该合金的急冷态和退火态组织，测定了合金在 同温度下退火10h后的显微硬度。结果表明，快速凝固Al-2.5Ti-2.5Fe合金稳冷态组织中存在两种初生相：Al3Ti相和Al5Ti2相；而经300℃退火10h后，将发生亚稳相Al5Ti向稳定相Al3Ti 的转变；经400℃退火10h后，组织中出现了平衡稳定相Al13Fe4，且在热处理过程中弥散析出Al3Ti相。     

快速凝固Al-Zr-Ti合金的组织结构

利用透射电子显微镜研究了快速凝固Al-Zr-Ti合金的组织结构。结果表明：快凝合金的显微硬度与其显微组织密切相关，快凝合金激冷态组织显示出单一相－过饱和Al基固溶体，此时显微硬度为220HV。快凝合金经420℃退火4h，具有立方结构的亚稳相L1-Al3(Zr,Ti) 析出，此时显微硬度达到峰值260HV。而经420℃退火20h，则L12相转变为DO23相，同时，显微硬度下降到150HV。     

快速凝固Al89—Ni10—Zr1合金的显微组织演化

利用透射电镜对快速凝固和热处理态的Al89－Ni10－Zr1合金的显微组织演化进行了研究。结果表明：急冷态组织中含有Al固溶体和Al3Ni颗粒。低温（350℃）热处理导致Al3Ni相析出。高温（450℃）热处理,在较短时间（4h）内有亚稳面心立方Ll2－Al3Zr相从过饱和固深体中析出,而经较长时间（8h）处理,其Ll2－Al3Zr相向平衡相互正方DO23－Al3Zr转变。     

快速凝固Al-Cu-Mg-Fe-Ni合金的微观组织和力学性能

利用X射线衍射、差示扫描量热(DSC)、透射电镜(TEM)研究了快速凝固Al 4Cu Mg 3Fe 4Ni (质量分数,% )合金急冷态和退火态的微观组织,同时测定了该合金的显微硬度。结果表明:快凝合金急冷态组织为过饱和αAl基固溶体和Al3Ni相;当快凝合金经40 0℃Xw 1h处理后,有少量S相(CuMgAl2 )析出;经40 0℃Xw 9h处理后,出现了FeNiAl9弥散相;在合金组织中未见Al Cu Fe和Al Cu Ni相。随时效时间的增加,快凝合金的显微硬度不断增加,达到峰值后硬度缓慢下降,之后随FeNiAl9析出,硬度又重新增加。     

非晶Al85Y4Nd4Co7合金及其晶化行为

采用单辊旋淬快速凝固方法制备出Al85Y4Nd4Co7的合金薄带,对快速凝固合金进行差示扫描量热(DSC)、X射线衍射(XRD)和透射电镜(TEM)分析.结果表明,在铸态时,得到完全非晶组织;经280℃×1.5 h退火,快凝合金中有α-Al析出;经350℃×1.5 h退火处理后,有Al3Y和Al9Co2相析出;450℃×1.5 h退火后,有新相A13Nd和未知相析出,且已有晶粒都明显长大.     

快速凝固Al—Zr—Ti合金的组织结构

利用透射电子显微镜研究了快速凝固Al-4Zr-2Ti(原子百分比）合金的组织结构。结果表明：快凝合金的显微硬度与其显微组织密切相关,快凝合金急冷态组织显示出单一相-过饱和Al基固溶体,此时显微硬度为220HV,快凝合金经420℃退火4h ,具有立方结构的亚稳相L12-Al3(Zr、Ti)析出,此时显微硬度达到峰值260HV,而经420℃退火20h,则L12相转为为DO23相,同时,显微硬度下降到150Hv。     

Al91Ni7Y2纳米非晶复合材料晶化的研究

利用差示扫描量热（DSC）、透射电镜（TEM）和X射线衍射（XRD）技术对快速凝固Al91Ni7Y2合金条带急冷态和不同温度退火态的晶化行为及显微结构演化进行了研究。结果表明：急冷态的Al91Ni7Y2合金为部分Al粒子均匀分布在非晶基底上的复合材料。从急冷态到高温平衡态有三阶段晶化过程，对所有的晶化温度和晶化相的测量表明，DSC曲线上有一个峰的初始和峰值温度分别为240℃和267℃（在加热速率为10℃／min条件下），这一相对高的温度表明此复合材料有高的热稳定性。     

热处理对含γ′相抗磨耐热钢组织和硬度的影响

研究了时效和退火处理对添加Al形成Ni3Al（γ′）相的抗磨耐热钢组织和硬度的影响。结果表明,时效处理后,金属间化合物Ni3Al相由颗粒状变为圆球状,800℃保温15h时效后硬度比铸态时提高了22.0%;退火处理后颗粒状Ni3Al相变为圆球状的同时尺寸大幅减小,1200℃保温4h油冷退火后硬度比铸态时提高了35.9%,而保温5h后的组织更为均匀,硬度值稍低于保温4h后的。综合组织和性能的分析,选择最佳的热处理工艺为1200℃保温5h油冷。     

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).     

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.     

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.