Interphase migration and enrichment of lead and zinc during copper slag depletion

An interphase migration and enrichment model of lead and zinc during molten copper slag depletion was established.The occurrence of various components in copper slag was predicted using sulfur-oxygen potential calculations and confirmed through high-temperature experiments.The recovery rate of copper can reach 90.13%under the optimal conditions of 1200°C,an iron to silicon mass ratio of 1.0,3 wt.%ferrous sulfide,and a duration of 45 min.Lead(54.07 wt.%)and zinc(17.42 wt.%)are found in the flue dust as lead sulfate,lead sulfide,and zinc oxide,while copper matte contains lead(14.44 wt.%)and zinc sulfide(1.29 wt.%).The remaining lead and zinc are encapsulated as oxides within the fayalite phase.

动载下含表面裂纹岩石破坏的近场动力学模拟

为了研究动态加载下岩石表面裂纹的扩展,基于前期试验结果使用一种考虑压缩和拉伸强度比的弹塑性常规态基近场动力学模型进行数值试验。模拟动态加载下含不同角度和深度三维表面裂纹岩石的破坏过程。模拟结果表明,使用的近场动力学模型可以很好地模拟岩石三维裂纹的扩展和试样的破坏过程。通过近场动力学模拟可以得到与试验结果一致的强度变化规律。试样表面形成的裂纹深入试样内部一定深度,该深度与表面裂纹深度有关。试样内部产生的壳裂纹会与表面形成的裂纹连接形成复杂的三维裂纹。

基于融合策略的块体金属玻璃形成能力预测

提出一种融合策略来提高随机森林(RF)、k近邻(KNN)、梯度提升决策树(GBDT)和极端梯度提升(XGBoost)模型预测块体金属玻璃(BMGs)形成能力(GFA)的准确性。该策略使用训练好的卷积神经网络(CNN)模型提取来特征向量,且合金的成分信息是唯一的输入变量,不需要通过实验获得其他物理和化学特性。此外,通过网格搜索方法和k折交叉验证对RF、KNN、GBDT和XGBoost模型的超参数进行了优化。结果表明,本文作者提出的4种融合模型CNN-RF、CNN-KNN、CNN-GBDT和CNN-XGBoost比上述4种机器学习模型(即RF、KNN、GBDT和XGBoost模型)预测精度更高,这表明训练好的CNN模型比人工特征提取更为高效。此外,与已报道的机器学习模型和GFA判据相比,本文作者提出的融合模型可以更精准地预测金属玻璃的形成能力。

Bonding enhancement of cold rolling TA1 P-Ti/AA6061 composite plates via surface oxidation treatment

TA1 P-Ti/AA6061 composite plate was produced by oxidizing the surface of the titanium plate and adopting a cold roll bonding process.The results revealed that the oxide film(Ti6O)prepared on the surface of TA1 pure titanium was easy to crack during the cold roll bonding,thereby promoting the formation of an effective mechanical interlock at the interface,which can effectively reduce the minimum reduction rate of the composite plates produced by cold rolling of titanium and aluminium plates.Moreover,the composite plate subjected to oxidation treatment exhibited high shear strength,particularly at a 43%reduction rate,achieving a commendable value of 117 MPa.Based on oxidation treatment and different reduction rates,the annealed composite plates at temperatures of 400,450,and 500°C displayed favorable resistance to interface delamination,highlighting their remarkable strength-plasticity compatibility as evidenced by a maximum elongation of 31.845%.

高速列车铜基摩擦材料的氧化行为

高速列车铜基摩擦材料在制动过程中,由于摩擦热的产生和耗散,会发生循环氧化。研究铜基摩擦材料在300、400、500、600和700℃下等温氧化50h的氧化行为。结果表明:铜基摩擦材料的氧化行为呈现多阶段特征;Cu、Fe的氧化与氧的扩散共同控制着低温氧化过程,而石墨的氧化在500℃之后占主导作用;Cu的氧化首先形成Cu_(2)O纳米团簇,然后生成CuO纳米线,最后依次转变为细小的和粗大的等轴晶;氧化温度的升高会促进Fe_(2)O_(3)纳米片的生长和致密化;Cu氧化物由于体积膨胀较大,逐渐将Fe氧化物覆盖;石墨烧蚀后形成的连通孔为内氧化提供氧气扩散通道;材料表面氧化层的形成使得表面硬度提高。

焊层排布对5083/6005A铝合金熔化极气体保护焊接接头显微组织及力学性能的影响

研究焊层排布方式对5083/6005A铝合金熔化极气体保护焊接(GMAW)接头显微组织及力学性能的影响。采用两层两道、两层三道和三层三道3种焊层排布方式获得高质量的对接接头。结果表明,位于6005A铝合金侧热影响区的软化区是5083/6005A铝合金GMAW接头的最薄弱部位。两层两道接头的热影响区再结晶程度和沉淀相溶解程度最高,而三层三道接头的最低。随着焊接层数和道次的增加,部分熔化区的晶界液化程度以及软化区的强度损失得到改善。两层两道接头的抗拉强度为161 MPa,而三层三道接头的抗拉强度提高到217 MPa。

不同熔盐体系中Sb_(2)S_(3)一步电还原脱硫

对NaCl-KCl、NaCl-CaCl_(2)、NaCl-Na_(2)CO_(3)、NaCl-KCl-CaCl_(2)和NaCl-KCl-Na_(2)CO_(3)熔盐体系开展比较分析,研究不同熔盐体系的相图、热稳定性和硫化锑的溶解度。根据锑元素分布特征、电流效率、能耗及熔渣成分表征结果,优选出适合Sb_(2)S_(3)电解还原的熔盐体系。结果表明,所有熔盐体系均具有良好热稳定性,且可实现Sb_(2)S_(3)的电解还原。添加CaCl_(2)的体系不利于Sb_(2)S_(3)溶解,而添加Na_(2)CO_(3)的体系会与Sb_(2)S_(3)发生反应。此外,NaCl-KCl体系的电流效率最高(75.68%),且能耗最低(2.18 k W·h/kg)。

超声空化作用下高温合金废料中战略金属的浸出机理

为提高高温合金废料中战略金属的回收效率,提出一种超声辅助浸出工艺。在超声辅助浸出过程中,浸出时间为60 min时,高温合金废料中Re、Ni、Co、Al、Cr和W的浸出率分别为92.3%、95.2%、98.5%、98.7%、97.5%和27.2%,明显优于常规浸出工艺中浸出时间为120 min时的浸出效率。高温合金废料中战略金属浸出效率的提高可归因于超声空化作用下产生的物理和化学协同作用。超声空化的物理作用可以阻止高温合金废料表面溶解层的形成,促进浸出液与高温合金废料接触,从而提高高温合金废料中战略金属的浸出率;而超声空化的化学作用可以促进HCl-H_(2)O_(2)体系中羟基自由基的产生,从而增强浸出体系的电位,促进体系中Re向ReO_(4)^(-)的氧化反应过程。

ZK61M高强镁合金板热变形过程中的韧性断裂预测

为了预测ZK61M高强镁合金板热变形过程的韧性断裂行为,在一定条件下进行实验和数值模拟。基于获得的各试件断口处的应力状态参数和断裂应变数据,采用粒子群优化算法求解4种断裂模型中的待定系数。依据误差评估结果,确定改进的Wilkins模型精度最高。将改进的Wilkins模型引入有限元中,并与实验进行对比。结果表明,预测的拉伸件断裂位移和断裂载荷的平均误差均小于15%,预测的圆筒形件成形深度的平均误差为13.88%,建立的有限元模型可以较为准确地模拟实验过程并预测断裂位置。

热处理对空心玻璃微球增强Mg−15Al−5Zn−1.5Cu复合材料力学性能和降解行为的影响

通过热处理改善空心玻璃微球/镁合金(Mg−15Al−5Zn−1.5Cu)可溶复合材料的综合性能,采用金相显微镜和扫描电子显微镜等手段分析复合材料在热处理过程中的微观结构变化。通过压缩试验、浸泡试验和电化学测试等手段探究热处理条件对复合材料的力学性能和溶解行为的影响,并揭示其影响机理。结果表明,热处理主要通过影响Mg17Al12相和Al2CuMg相数量、形态和分布影响复合材料的力学性能和溶解速率;经420℃固溶处理20 h和200℃时效处理24 h后,复合材料的基体晶粒组织和析出相分布更加均匀,成分偏析和残余应力被消除。获得了优异的综合性能,极限抗压强度、布氏硬度和断裂应变分别可达435 MPa、HB 124和8.3%,室温下在3%KCl(质量分数)溶液中的平均溶解速率可达151 mg/(cm^(2)·d),更有利于该复合材料在可溶井下工具中的应用。

高能喷丸制备具有表面梯度结构的Ti-6Al-4V合金的疲劳裂纹扩展行为

通过高能喷丸(HESP)在Ti-6Al-4V合金表面成功制备梯度结构,并研究其对疲劳裂纹扩展的影响。采用光学显微镜、扫描电子显微镜、透射电子显微镜和X射线衍射仪对HESP过程中的显微组织和残余应力演变进行表征。结果表明,材料表面形成的梯度纳米结构具有220μm深度的残余压应力层。梯度纳米结构的产生能改善合金的强塑性匹配。最大残余压应力产生于次表层,且随着喷丸时间的增加逐渐增大。HESP处理有效降低裂纹扩展速率,提高疲劳裂纹扩展寿命。残余压应力可降低裂纹尖端的有效应力强度因子范围(ΔK’eff),从而产生裂纹闭合效应并延缓裂纹扩展。同时,晶粒细化引起的晶界增加、有效滑移长度减小和裂纹尖端塑性区的协同作用也会使裂纹扩展阻力增大。

辊弯成形下塑性应变对挤压态6063T66铝合金型材疲劳性能的影响

分析从辊弯成形型材区和预应变材料取样的材料的拉伸塑性应变。利用概率Weibull累积分布(P-S-N曲线)近似高周疲劳的实验数据。利用LS-Dyna程序和实验数据对辊弯成形进行数值模拟,建立疲劳寿命预测模型。材料的循环行为表明,随着静态失效水平的增加,疲劳寿命分布减小。断裂表面的断口形貌分析表明,由于晶界附近的位错积累,拉伸预应变的晶间裂纹水平增加。所提模型预测结果与概率散射带具有良好的相关性(误差低于10%)。

Effects of various rare earth oxides on morphology and size of oxide dispersion strengthening(ODS)-W and ODS-Mo alloy powders

Ultrafine oxide dispersion strengthening(ODS)-Mo and ODS-W alloy powders containing different types of oxide nanoparticles were successfully synthesized by spraying method(solid−liquid mixing method)combined with the reductions with carbon black and hydrogen in sequence.It is concluded that the solution concentration and type of rare earth oxide have no effect on the grain size of ODS-Mo alloy powder,but have obvious effect on that of ODS-W alloy powder.The higher the concentration of rare earth solution is,the smaller the average grain size of ODS-W alloy powder is.Furthermore,compared with doping with CeO_(2),the grain sizes of reduction products of La_(2)O_(3) and Y_(2)O_(3) doped WO_(3) are relatively larger.Compared with the undoped case,there is almost no change for grain size of ODS-Mo alloy powder,while the grain size of ODS-W alloy powder becomes much larger.This is probably due to the appearance of the composite oxide(such as La_(2)WO_(6))formed by the reaction between tungsten oxide and rare earth oxides,which promotes the heterogeneous nucleation and growth of tungsten grains during the reduction process of ODS-W,while there is no complex oxide composed of molybdenum and rare earth oxides in the reduction process of ODS-Mo.

A novel approach for evaluation of load bearing capacity of duplex coatings on aluminum alloy using PLS and SVR models

Duplex NiP/TiN coatings consisting of the electroless intermediate layers and the physical vapor deposition(PVD) top layers were fabricated on the AA6061 aluminum alloy in order to enhance the load bearing capacity. The main objective of this study was to model the load bearing based on the thickness, adhesion and elastic modulus of the coatings. For this purpose, partial least square(PLS) and support vector regression(SVR) approaches were employed.The results showed that both models had an acceptable performance;however, the PLS model outperformed SVR. The correlation coefficients between thickness, adhesion and elastic modulus with load bearing were 0.841, 0.8092 and 0.7657, respectively;so, thickness had the greatest effect on the load bearing capacity. The composition and structure of the samples were evaluated using XRD and SEM. The load capacity of the coated samples was also discussed based on the wear and adhesion evaluations. Dry sliding wear tests, under a load of 2 N and a sliding distance of 100 m,demonstrated the complete destruction of the coated specimens with low load capacity. The samples with high load capacity showed not only a superior tribological performance, but also a remarkable adhesion according to the Rockwell superficial hardness test.

In-situ hydrothermal synthesis of Ni−MoO_(2)heterostructure on porous bulk NiMo alloy for efficient hydrogen evolution reaction

The Ni−MoO_(2) heterostructure was synthesized in suit on porous bulk NiMo alloy by a facile powder metallurgy and hydrothermal method.The results of field emission scanning electron microscopy(SEM),field emission transmission electron microscopy(TEM)and X-ray photoelectron spectroscopy(XPS)reveal that the as-prepared electrode possesses the heterostructure and a layer of Ni(OH)_(2) nanosheets is formed on the surface of Ni−MoO_(2) electrode simultaneously after hydrothermal treatment,which provides abundant interface and much active sites,as well as much active specific surface area.The results of hydrogen evolution reaction indicate that the Ni−MoO_(2) heterostructure electrode exhibits excellent catalytic performance,requiring only 41 mV overpotential to reach the current density of 10 mA/cm^(2).It also possesses a small Tafel slope of 52.7 mV/dec and long-term stability of electrolysis in alkaline medium.

Evolution of V-containing phases during preparation of Al-based Al−V master alloys

Al-based Al−V master alloys were prepared by both the stepwise heating melting experiment and stepwise melting cooling experiment with rapid solidification to investigate the transformation of V-containing phases which gave different effects on microstructures and properties of commercial Al alloys and Ti alloys,as both melting and solidification processes affect the evolution of V-containing phases largely.The results showed that the raw Al−50wt.%V alloy consisted of needle-like Al_(3)V phase and Al8V5 phase(matrix),while petal-like Al_(3)V,needle-like Al_(7)V and plate-like Al_(10)V phase were present in the Al−V master alloys.The metastable Al_(7)V phase was evolved from Al_(3)V phase and then evolved into Al_(10)V phase during melting process.The number of Al_(10)V phase increased with the decrease of temperature in the range of 800−1000℃.Petal-like Al_(3)V phases could be transformed from Al_(8)V_(5) phase,pre-precipitated from Al−V molten liquid during melting process and precipitated directly during rapid solidification,respectively.

Corrosion resistance improvement of Ti-6Al-4V alloy by anodization in the presence of inhibitor ions

Colorful thin oxide films were synthesized by galvanostatic anodization on Ti−6Al−4V alloy.Three different aqueous solutions containing corrosion inorganic inhibitors(Na_(2)MoO_(4),NaH_(2)PO_(4) and NH4VO3)were employed for the anodization treatment.The effect of inhibitor anions on the corrosion behavior of the alloy in Ringer solution was studied.Open circuit potential(OCP),Tafel polarization,linear sweep voltammetry(LSV)and chronoamperometry(CA)were performed to evaluate the corrosion performance of the treated electrodes.The incorporation of the inhibitor ions was detected by the release of Mo,V and P through ICP-AES technique.The formed oxides were characterized by scanning electron microscopy(SEM),X-ray diffraction(XRD)and X-ray photoelectron spectroscopy(XPS).The results show that compact,amorphous oxides without pores or cracks were obtained independently of the solution used.The sample anodized in Na_(2)MoO_(4) solution registered the lowest corrosion current density(0.11μA/cm^(2)),and it was able to protect the alloy even after 168 h of immersion in Ringer solution.No cracks or corrosion products were detected.The XPS analysis reveals the incorporation of molybdenum to the oxide film in the form of Mo^(6+) and Mo^(4+).

Microstructure,formation mechanism and properties of plasma-sprayed Cr_(7)C_(3)−CrSi_(2)−Al_(2)O_(3)coatings

The Cr_(7)C_(3)−CrSi_(2)−Al_(2)O_(3)composite coatings were prepared by plasma spraying Cr_(7)C_(3)−CrSi_(2)−Al_(2)O_(3)and Al−Cr2O3−SiC composite powders,respectively.The microstructure,formation mechanism and properties of the two Cr_(7)C_(3)−CrSi_(2)−Al_(2)O_(3)composite coatings obtained by plasma spraying were investigated,and the reaction mechanism of the Al−Cr_(2)O_(3)−SiC system was explored.The results show that the coating obtained by plasma spraying Al−Cr_(2)O_(3)−SiC composite powders had thinner lamella and more tortuous interlayer interface,and the in-situ synthesized Cr_(7)C_(3),CrSi_(2) and Al_(2)O_(3) in the coating were all nano-crystallines.Compared with the Cr_(7)C_(3)−CrSi_(2)−Al_(2)O_(3)coating prepared by plasma spraying Cr_(7)C_(3)−CrSi_(2)−Al_(2)O_(3)composite powders,the plasma-sprayed Cr_(7)C_(3)−CrSi_(2)−Al_(2)O_(3)coating obtained from Al−Cr_(2)O_(3)−SiC composite powders had higher density,higher microhardness(increased by 20%),better fracture toughness and lower wear rate(reduced by 28%).

Effect of Nd addition on microstructure and tensile properties of laser additive manufactured TC11 titanium alloy

Single-layer and multilayer laser additive manufacturing(LAM)for TC11 alloy with different Nd additions was conducted and the effect of Nd addition on microstructure and properties was studied.With the addition of Nd,the aspect ratio of melting pools of single-layer specimens increases and the columnar-to-equiaxed transition occurs.The originalβgrain size andαplate width of TC11−1.0Nd are significantly reduced compared with those of pure TC11 specimens.It is proposed that the evenly distributed fine Nd_(2)O_(3) precipitates of about 1.51μm are formed preferentially during rapid solidification of melting pool,and they serve as heterogeneous nucleation particles to refine the microstructure in the subsequent solidification and solid-state phase transformation.Due to the multiple effects of Nd on the microstructure,the ultimate tensile strength of TC11−1.0Nd increases,while the yield strength,ductility and microhardness decrease compared with those of pure TC11.

Nucleation and growth mechanism of electrodeposited Ni−W alloy

The nucleation and growth mechanism of electrodeposited Ni−W alloy were investigated.Cyclic voltammetry(CV)and chronoamperometry(CA)were used to examine the electrochemical behavior and nucleation mechanism of the electrodeposited Ni−W alloy.The nucleation type and kinetic parameters of the electrodeposited Ni−W alloy were obtained from the CA analysis results.SEM,AFM,and TEM were also used to investigate the nucleation and growth process of the electrodeposition of Ni−W alloy.The results demonstrate that the nucleation and initial stages of the growth phase of the Ni−W alloy undergo the formation,movement,and aggregation of atoms,single crystals,and nanoclusters.When the size of single crystal increases up to approximately 10 nm and the average size of the crystal granules is approximately 68 nm,they no longer grow.Increasing the applied potential increases the number of nuclei but does not affect the size of the final crystal granules.Therefore,the electrodeposited Ni−W alloy shows a nanocrystalline structure.