Al-Zr-B体系反应合成复合材料的组织和性能

开发了原位合成Al-K2ZrF6-KBF4新体系，利用熔体反应法成功制备了新型颗粒增强铝基复合材料。XRD和SEM分析表明，合成的复合材料中存在ZrB2和Al3Zr颗粒，颗粒大小为1～4μm，ZrB2颗粒的截面形貌接近于正六边形，且在基体中均匀分布。拉伸试验结果表明，（Al3Zr＋ZrB2）p／Al复合材料的抗拉强度和屈服强度随着反应物加入量的增加而提高。当反应物加入质量分数为20％时，复合材料最高抗拉强度达到152．3MPa，比铝基体提高了95．2％；屈服强度为112．3MPa，比铝基体提高了167．3％。     

Al-Zr(CO3)2体系反应生成Al基复合材料的力学和磨损性能研究

运用Al-Zr（CO3）2体系熔体反应法制备了（Al3Zr＋Al2O3）p／Al合材料，研究了（Al3Zr＋Al2O3）p／Al复合材料的力学和磨损性能。结果表明：Al-Zr（CO3）2与Al熔体反应生成了Al2O3、Al3Zr颗粒；（Al3Zr＋Al2O3）g/A复合材料的抗拉强度和屈服强度随颗粒理论体积分数的增大而提高，当颗粒体积分数为10％时，复合材料的Rm为148．3MPa，较铝基体提高了90．1％，复合材料的Rp02为110．5MPa，较铝基体的提高了163．1％，复合材料的断后伸长率先升后降；由复合材料的拉伸断口SEM可知：随着反应物质量增加，塑性变形区减小，但仍是塑性断裂；由磨损表面SEM观察表明：（Al3Zr＋Al2O3）p/Al复合材料的磨损特征为黏着磨损和磨粒磨损的混合型磨损。     

Al-Zr-O体系熔体反应法合成复合材料的微观组织和拉伸性能

采用熔体反应法 ,以ZrO2 、ZrSiO4 和ZrOCl2 粉剂为反应物在熔融的铝 ( 85 0℃ )中成功制备了Al/ (Al3 Zr Al2 O3 ) P 复合材料。扫描电镜 (SEM )和电子探针 (EPMA)分析表明 :Al Zr O体系反应生成的复合材料 ,颗粒尺寸细小 ,Al2 O3 为 1～ 3μm ,Al3 Zr小于 1μm ,且弥散分布于基体中。拉伸试验结果显示 :Al Zr O体系反应生成Al/ (Al3 Zr Al2 O3 ) P 复合材料的抗拉强度和屈服强度较基体纯Al均显著提高。其中Al ZrOCl2 体系生成的复合材料的抗拉强度为14 8 7MPa ,屈服强度为 112 4MPa ,分别较基体纯Al提高了 93 6 %和 170 8%。     

Al-Zr(CO_3)_2体系反应合成复合材料的力学性能与断裂行为①

利用Al Zr(CO3)2原位反应体系,采用熔体反应法制备了(Al3Zr Al2O3)p/Al复合材料。XRD及SEM分析显示:原位反应生成的颗粒为Al3Zr和Al2O3,颗粒细小并均匀分布在基体中。拉伸实验表明:(Al3Zr Al2O3)p/Al复合材料的抗拉强度和屈服强度随颗粒含量的增大显著提高,当颗粒体积分数为10%时,复合材料的抗拉强度和屈服强度分别为148.3MPa和110.5MPa,但延伸率先上升后下降。原位拉伸研究表明:复合材料拉伸过程中裂纹的萌生及扩展机制可从两方面得到解释:滑移过程中的位错作用机制以及颗粒脱粘和破碎形成的"孔洞"成核与长大机制。     

Al-Zr(CO3)2体系反应合成复合材料的力学性能与断裂行为

利用Al-Zr(CO3)2原位反应体系,采用熔体反应法制备了(Al3Zr Al2O3)p/Al复合材料.XRD及SEM分析显示:原位反应生成的颗粒为Al3Zr和Al2O3,颗粒细小并均匀分布在基体中.拉伸实验表明:(Al3Zr Al2O3)p/Al复合材料的抗拉强度和屈服强度随颗粒含量的增大显著提高,当颗粒体积分数为10%时,复合材料的抗拉强度和屈服强度分别为148.3 MPa和110.5 MPa,但延伸率先上升后下降.原位拉伸研究表明:复合材料拉伸过程中裂纹的萌生及扩展机制可从两方面得到解释:滑移过程中的位错作用机制以及颗粒脱粘和破碎形成的"孔洞"成核与长大机制.     

Al-Zr-O-B原位合成复合材料的微观组织和力学性能

采用Al-Zr(CO3)2-KBF4体系用熔体反应法成功合成了新型颗粒增强铝基复合材料.XRD和SEM分析表明, Zr(CO3)2和KBF4与铝液反应生成了ZrB2、Al2O3、Al3Zr颗粒,颗粒尺寸细小,且弥散分布于基体中,其平均尺寸约为80～90 nm;拉伸试验结果显示.Al-Zr(CO3)2-KBF4体系反应生成的复合材料的抗拉强度和屈服强度随着反应物加入量的增加均显著提高,复合材料的抗拉强度为150.3 MPa,较铝基体的78.0 MPa提高了 92.7%;屈服强度为113.7 MPa,较铝基体的42.0 MPa提高了170.7%;复合材料的伸长率先升后降;由复合材料的拉伸断口SEM可知,随着反应物质量增加,塑性变形区减小,但仍然是塑性断裂.     

脉冲磁场下Al-ZrSiO4体系原位合成复合材料及其微观组织

在脉冲磁场下，以Al-ZrSiO4为反应体系成功制备了内Al3Zr和Al2O3颗粒增强铝基复合材料。用X射线衍射仪（XRD）、扫描电镜（sEM）、电子探针（EPMA）等研究了（Al2O3＋Al3Zr）p／Al复合材料的相组成、凝固组织和内生增强体的特征。试验结果表明，在脉冲磁场作用下，原位合成的颗粒细小，呈矩形或短棒状的A13Zr颗粒尺寸为1～3μm，形状圆整的Al2O3颗粒尺寸小于2μm，且弥散分布于基体中。随着外加脉冲磁场强度的增大，反应生成的增强颗粒变得更加细小，分布更均匀。外加脉冲磁场作用时间短，颗粒体积分数低，颗粒粗大；作用时间长，颗粒体积分数明显下降，部分颗粒开始团聚长大，最佳的作用时间为15～20min。     

高强度TiN-AlNp/Al-Si复合材料的制备

提出一种新型的熔体搅拌铸造工艺 ,解决了Al Si合金对 10 μm级以下高体积分数TiN ,AlN陶瓷的非真空无压浸润问题 ,并在此基础上成功制备了高强度低成本的TiN AlNp/Al Si复合材料。研究表明 ,细小TiN ,AlN颗粒在铝熔体中已经实现了润湿 ,平均尺寸在 2～ 3μm ,基本呈均匀分布 ,与基体结合良好。当TiN ,AlN的含量为10 % (体积分数 )时 ,复合材料的抗拉强度为 335MPa ,屈服强度为 2 40MPa ,延伸率为 2 .4%。     

真空热压SiC_p/2024Al复合材料力学性能与显微结构

采用真空热压法制备了体积分数为30%的Si Cp/2024Al复合材料,研究了该复合材料的显微组织结构及力学性能。结果表明,复合材料组织致密,颗粒与基体界面结合状况较好,Si C颗粒在铝基体中基本上分布均匀。经490℃、2 h固溶处理和170℃、8 h人工时效后,Si Cp/2024Al复合材料的抗拉强度、屈服强度和伸长率分别为409 MPa、325 MPa和4.9%,基体中存在大量的纳米析出相为S'(Al2Cu Mg)。随Si C颗粒加入,复合材料力学性能提高,其断裂方式为基体开裂和界面处撕裂。     

混合粉末半固态成形Al7075/B_4C复合材料在不同实验条件下的显微组织和力学行为（英文）

通过混合粉末半固态成形法制备B_4C增强铝基复合材料。先将Al7075元素粉末在机械搅拌状态下逐渐添加到酒精溶液中,然后通过高能球磨将Al7075元素粉末与B_4C颗粒混合,最后将Al7075/B_4C混合粉末在半固体状态下冷压成型。研究基体颗粒尺寸(20、45和63μm)、增强相的体积分数(5%、10%和20%)和半固态压制压力(50和100 MPa)对复合材料的形貌、显微组织、密度、硬度、压缩强度和抗弯强度的影响。实验结果表明,当大的B_4C颗粒(45μm)分布在小的基体相颗粒(20μm)中时,材料的显微组织最均匀。基体颗粒尺寸大于增强相颗粒尺寸的复合材料中团聚量大于10%(体积分数)。团聚区域的液相难以渗透到孔隙中,降低复合材料的密度和强度。采用20μm Al7075和20%(体积分数)45μm B_4C粉末在100 MPa下压制的复合材料表现出最高的硬度值(HV 190)和抗压强度(336 MPa)     

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.