Al—Cu共晶合金熔体中稀土Ce与氢的相互作用

研究了不同稀土Ce含量对共晶成分Al-33.2Cu (质量分数,％,下同）熔体氢含量的影响。结果表明：在相同的保温时间和保温温度条件下,稀土的加入增加了合金熔体的氢含量。750℃,保温20min,加入0．6的Ce,Al-Cu共晶合金熔体的氢含量由0．06mL/100g增至0．16mL/100g。研究了不同Ce含量Al-Cu共晶合金熔体氢含量随温度变化的规律。实验 温度分别为720℃,750℃,800℃和850℃,含0．6Ce的Al-Cu共晶合金熔体氢含量的值分别为0．14、0．16、0．23和0．29mL/100g。     

Sn-Ag-Cu-Ce无铅钎料合金体系的热力学计算及预测

利用周模型对Sn—Ag—Cu—Ce无铅钎料合金体系进行了热力学计算预测。热力学计算结果表明，Ag、Cu含量(质量分数)分别为0．5％-4．5％时，当Ce的含量(质量分数)超过0．05％时，体系达到化学平衡状态；当Ce的含量(质量分数)达到0．6％左右时，Sn、Ag、Cu分别都出现了“等活度系数”现象。这一研究结果可为无铅钎料合金的成分设计提供理论指导。     

合金元素Cu对过热铝熔体中氢含量的影响

Ａｌ－Ｃｕ合金熔体中的氢含量在７８０℃以下保持恒定，此后氢含量随温度升高急剧增加，分析表明合金元素Ｃｕ在７８０℃以下对过热名熔体中的氢含量起主导作用，即在此温度以下铝液吸氢程度取决于铝液表面氧化膜的性质。试验研究表明在同一热度下，铝熔体中氢含量随合金元素Ｃｕ加入量的增多而下降。     

含Zr多晶Ni3Al合金在不同热处理温度下的组织与性能

研究了冷轧多晶Ni3Al-(0．2％，0．6％，1．0％，1．5％)Zr(原子分数)合金在不同热处理温度(800-1100℃)下的显微组织和力学性能，结果表明，适当的热处理温度，可使无硼Ni3Al-Zr多晶合金获得优良的室温拉伸强度和塑性，随着热处理温度的升高，不同Zr含量Ni3Al合金的再结晶体积分数增加，再结晶晶粒尺寸增大，室温拉伸强度下降．随着合金中Zr含量的增加，再结晶温度降低，再结晶晶粒尺寸减小．不同Zr含量Ni3Al合金的拉伸塑性明显依赖于热处理温度，对于低Zr(0．2％)合金，在1000℃热处理后，拉伸塑性最佳；对于中Zr(0．6％)合金，在850℃热处理后，拉伸塑性达到最大值；对于高Zr(≥1．0％)合金，拉伸塑性峰值出现在900℃热处理下，当热处理温度超过900℃，拉伸塑性显著降低。     

Effects of Thermal Exposure on the Tensile and Fatigue Properties of Cast Ti—47Al—2Cr—2Nb--0.15B Alloy

测量了铸造Ti—47Al—2Cr—2Nb-0．15B(原子分数，％)合金的高温疲劳强度以及650℃／100h和800℃／100h热暴露后的拉伸性能和疲劳强度，采用X射线衍射和扫描电镜等方法分析了经热暴露后合金基体组织的变化和表面层的结构．随暴露温度的提高，合金的室温塑性和疲劳强度降低，650℃附近有一转折点，大于650℃时上述性能加速下降；合金高温疲劳性能具有相似的变化规律．显微分析表明，在热暴露或高温疲劳实验时，表面形成的脆性层是导致合金性能降低的直接原因；而随温度的提高，表面层由渗氧层转变为氧化层是导致合金性能随温度变化出现转折的原因．     

微重力电磁模拟制备高锂含量铝锂合金

采用普通熔炼工艺制备的铝锂合金，锂的质量分数不超过3％，否则，合金会出现严重的偏析。利用电磁模拟微重力装置，将原料放入涂有BN的高纯石墨坩埚并装入炉中，抽真空到10Pa开始对炉体加热，温度达到300℃时充入氩气，使炉内压力维持在40Pa，合金温度达到760℃时停止加热，保温40min，在电磁铁中输入励磁电流并在熔体中加入直流电场，温度降至凝固温度时去掉电磁场，冷却至室温，可以制备出锂的质量分数为5％-10％的二元铝锂合金。试验证明：利用该方法解决了合金的偏析现象。     

熔体处理对A356合金半固态浆料组织的影响

研究了熔体处理对A356合金半固态浆料组织的影响，结果表明，适当的熔体处理工艺具有一定的生成非枝晶组织的作用，但很难实现半固态浆料的快速制备；“熔体处理＋双向电磁搅拌”复合技术具有较高的浆料制备效率，为流变成形的制浆提供了可能。同时，优化出A356合金的最佳熔体含量（质量分数），即0．6％的Al-5Ti-B和0．4％的A1-10Sr。     

Ti1．0VxMn（2-x）（x=0．6～1．6）合金的微结构和储氢性能

系统研究了V替代Mn对Ti1．0VxMn（2-x）（x=0．6～1．6）合金的相结构及吸放氢性能的影响。研究结果表明：随着X的增加，合金由Laves和bcc两相结构逐渐变化到bcc单相结构，吸氢量也随之增加；当V含量增加到x≥1．2时，合金具有bcc单相结构，合金最大吸氢量达到3．5％（质量分数），但是由于缺少脆性的Laves相，合金的活化性能变差，饱和吸氢时间也有所延长；随着V含量的增加，合金主相bcc相晶胞体积增大，从而导致合金PCT曲线平台压力降低，滞后效应也逐渐增大，但平台趋向于平缓。     

稀土La(镧)对Al-Si共晶合金性能的影响

在Al-Si共晶合金中加入不同含量的稀土元素La，研究其流动性及热处理后的力学性能。结果表明，含0．2％ La(质量分数，下同）的合金流动性较好，铸态时硬度和强度较高，淬火后，180℃时效4h，稀土La含量为0．2％－0．3％的合金表现出良好的综合力学性能。     

喷射成形Al-Zn-Mg-Cu合金的显微组织演变

采用喷射成形技术制备了高Zn含量的超高强度Al-12．40Zn-2．68Mg-2．40Cu合金(质量分数，％)．对合金进行热挤压，在不同固溶温度和时间下对挤压合金进行固溶处理，并进行力学性能测试．结果表明：随着固溶温度的升高及固溶时间的延长，第二相富Cu颗粒随之相应溶解，再结晶晶粒合并与长大；当固溶温度达到490℃时，富Cu颗粒相基本溶解，合金完全再结晶．合金进行T6热处理后，抗拉强度达到800MPa以上，延伸率为7．5％．     

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.