原位自生Al—4Cu—0.8Mg／TiGp复合材料半固态挤压的组织与力学性能

本文对自生Al-4Cu-0.8Mg/TiCp复合材料采用T4和T6两种热处理制度，测试了该材料的σb、σs、E和δ。通过SEM观察和分析了半固态挤压原位自生Al-4Cu-0.8Mg/TiCp复合材料的显微组织和断口形貌。结果表明：在T6状态下ω（TiCp）为15％的复合材料的σb、σs、E分别达到540MPa、430MPa、92GPa,δ为3．2％，断裂形式为韧性断裂，由此可以认为自生TiCp/2024复合材料具有优良的综合力学性能。     

原位自生Al-4Cu-0.8Mg/TiCp复合材料半固态挤压的组织与力学性能

本文对自生Al-4Cu-0.8Mg/TiCp复合材料采用T4和T6两种热处理制度,测试了该材料的σ_b、α_s、E和δo。通过SEM观察和分析了半固态挤压原位自生Al-4Cu-0.8Mg/TiCp复合材料的显微组织和断口形貌。结果表明:在T6状态下ω(TiCp)为15％的复合材料的σ_b、σ_s、E分别达到540MPa、430MPa、92GPa,δ为3.2%,断裂形式为韧性断裂,由此可以认为自生TiCp/2024复合材料具有优良的综合力学性能。     

自生TiC_P/Al-4Cu复合材料的组织与力学性能

应用反应合成工艺制备了自生TiCP/Al 4Cu复合材料。通过XRD分析了自生TiCP/Al 4Cu复合材料的相组成 ,用SEM观察了自生TiCP/Al 4Cu复合材料的微观组织和断口形貌 ,测试了自生TiCP/Al 4Cu复合材料的力学性能。结果表明 :自生TiCP/Al 4Cu复合材料增强颗粒细小圆整 ,在基体中分布均匀。在T6状态下具有优良的综合力学性能     

压铸TiC/AlSiCuMg复合材料的制备和性能

利用熔铸 -原位反应和压铸成形技术制备了TiC/AlSi9Cu1.4Mg0 .5复合材料 ,测试了复合材料的力学性能。结果表明 :TiC/AlSi9Cu1.4Mg0 .5复合材料的室温抗拉强度为 3 5 4MPa ,比基体合金提高 2 6% ;2 60℃时复合材料的抗拉强度为2 72MPa ,比基体合金提高 46%。复合材料的伸长率与AlSi9Cu1.4Mg0 .5合金相当     

磁化学合成（Al2O3＋Al3Zr）p/Al复合材料的微观组织与力学性能

以氧氯化锆(ZrOCl2·8H2O)为反应物,采用熔体反应法,并在反应过程中施加脉冲涡流磁场,磁化学合成了(Al2O3+Al3Zr)p/Al复合材料.扫描电镜(SEM)与X射线衍射(XRD)分析表明生成的颗粒为α-Al2O3和Al3Zr,颗粒细小,形状一致,且弥散分布于铝基体中;在相同反应条件下,与常规原位反应相比,磁场下反应更快、更完全,缩短了反应时间,并从反应动力学角度进行了分析.复合材料的力学性能研究表明,其屈服强度σs和抗拉强度σb均随颗粒体积分数的增加而升高,延伸率δ先升后降.(Al2O3+Al3Zr)p/Al复合材料的拉伸断口形貌表明,其断裂属塑性断裂.     

多元氧化物和铝原位反应制备铝基复合材料的组织和性能

采用SEM、EDS、XRD、TEM和拉伸强度测试等研究Al2O3粒子增强的ZL109铝基复合材料。结果表明:多元氧化物和铝原位反应生成的Al2O3粒子尺寸细小,粒径约为0.1μm,在基体中弥散分布,与基体存在共格关系,(001)α(Al)//(010)α-Al2O3,[110]α(Al)//[001]α-Al2O3。原位反应中生成的金属间化合物经T6处理后,以Al5FeSi、FeCr、Mg2Si、Al3Ni、Al2Cu和Al7Cu4Ni相的形式存在于基体中,使得复合材料在300℃的拉伸强度达到163.4 MPa,较基体的提高7.9%。随Al2O3粒子含量的增加,25℃时,复合材料断口断裂方式由韧性断裂转变为解理断裂,再到穿晶断裂;而300℃时,断口断裂转变方式为脆性断裂到延性断裂。     

海外文献速报

20050701НикитинСЛ.主要合金元素对Al Mg Si系合金组织、工艺性能的影响.Металл,2004(3):70～77研究了Al Mg Si系合金最佳Mg、Si含量范围,作出了铸态、T4热处理态镁含量和强度极限σb、屈服极限σ0.2、伸长率δ及断面收缩率α的关系图表,随镁含量上升,铸态时σb、σ0.2在Mg的质量分数为7.5%后不再升高,而δ则由于存在粗大的Mg2Si相而下降,至Mg的质量分数大于8.0%后接近于零,T4态时,σb、σ0.2、δ及α均单调升高,但w(Mg)>8.0%后升高相对缓慢,据此,最佳Mg含量范围为6.5%～8.0%,w(Mg)<6.5%时σb、σ0.2均明显降低;Si能…     

海外文献速报

20 0 5 0 40 1　НикитинСЛ .主要合金元素对Al Mg Si系合金组织、工艺性能的影响 .Металл ,2 0 0 4(3 ) :70～ 77研究了Al Mg Si系合金最佳Mg、Si含量范围 ,作出了铸态、T4热处理态镁含量和强度极限σb、屈服极限σ0 .2 、伸长率δ及断面收缩率α的关系图表。随     

La对原位自生Mg_2Si/Al复合材料组织及性能的影响

采用重力铸造法制备了原位自生Mg2Si/Al复合材料,研究了稀土La处理的Mg2Si/Al基复合材料的组织形貌和力学性能。结果表明,稀土La对Mg2Si/Al复合材料的凝固组织有影响;添加稀土处理的Mg2Si/Al基复合材料中的Mg2Si颗粒变得更加细小,La与Al相互作用形成Al11La3相可阻止Mg2Si相长大;添加La之后,铸态Mg2Si/Al基复合材料的力学性能得到改善,其抗拉强度和伸长率分别为108 MPa和2.56%。     

超声处理对原位Mg2Si/AM60复合材料的影响

采用连续功率超声对原位Mg2Si/AM60复合材料熔体进行处理,研究了超声处理对复合材料中的第二相形貌以及力学性能的影响。结果表明,经过600W超声处理60s,原位自生Mg2Si颗粒增强AM60复合材料中的半连续网状Mg17Al12转变成颗粒状,粗大的汉字状Mg2Si破碎成细小的颗粒状,较均匀地弥散分布,晶粒尺寸减少到80μm,其抗拉强度和伸长率较无超声的178.24MPa、3.56%分别提高了10.4%、48.3%,达到196.75MPa、5.28%。     

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.     

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.