熔覆电流对CoCrFeNiMo高熵合金涂层组织与耐磨性的影响

为了探索制备工艺对高熵合金涂层组织与性能的影响,利用氩弧熔覆方法在Q235钢表面制备了等摩尔比CoCrFeNiMo高熵合金涂层.采用光学显微镜(OM)、扫描电镜(SEM)、能谱仪(EDS)、X射线衍射仪(XRD)等研究了涂层的组织形貌及物相,采用显微硬度计和摩擦磨损试验机分析了涂层的硬度和耐磨性.结果 表明:采用氩弧熔覆方法能成功在Q235钢表面制备出厚度在2 mm以上的CoCrFeNiMo高熵合金涂层;靠近涂层顶部,熔覆电流对涂层的组织影响明显;随着熔覆电流的增加,涂层中上部过渡区组织由胞状晶向枝状晶和等轴晶转变,同时出现晶粒细化现象,BCC、FCC两相固溶体逐渐转变到BCC单相固溶体.随熔覆电流的增加,涂层的硬度和耐磨性均先升高后降低,涂层表层硬度最大,向基体方向呈下降趋势.当熔覆电流为200 A时,涂层的表层硬度最高,达626.7 HV0.2,约为Q235基体的4倍,其耐磨性也最好.涂层的磨损机制主要为粘着磨损,熔覆电流为200 A制备的涂层伴随有磨粒磨损.     

FeAlCuCrNiNbx系高熵合金堆焊层的组织及性能分析

为了研究Nb元素含量对FeAlCuCrNiNb_x(x = 0.4,0.6,0.8,1.0,x为摩尔比)高熵合金的组织结构及性能的影响,采用熔化极气体保护焊技术在碳钢板表面制备出FeAlCuCrNiNb_x高熵合金堆焊层,而后对堆焊层进行显微组织、物相组成、显微硬度、耐磨性和耐蚀性分析. 结果表明,FeCuCrAlNiNb_x高熵合金堆焊层呈现以Fe-Cr相为基的BCC固溶体和少量MC共晶碳化物. 组织为典型的枝晶结构,由灰色的枝晶(DR)及白色的枝晶间(ID)结构组成. 对于耐磨性,加入适量的Nb元素可以显著提高堆焊层的显微硬度和耐磨性,当Nb摩尔比为0.8时,显微硬度最高,耐磨性最好,最大硬度值达到602 HV,磨损量最小为0.30 g. 对于耐蚀性,加入一定量的Nb元素后极化曲线中自腐蚀电流密度减小,腐蚀速率减慢,耐蚀性增强,均优于304不锈钢,当Nb摩尔比为1.0时,堆焊层合金耐蚀性最好.     

冷喷涂辅助原位合成FeCoxCrAlCu高熵合金涂层组织性能研究

利用冷喷涂辅助原位合成高熵合金涂层的方法,在45_^#钢基体表面成功制备出不同Co含量的FeCo_xCrAlCu(x=0,0.5,1,1.5,2)高熵合金涂层。通过XRD、SEM、EDS、TEM、显微硬度计、磨料磨损试验机、电化学工作站等设备,检测分析了Co含量的变化对合金涂层相结构、显微组织,硬度、耐磨性及耐腐蚀性的影响。结果表明：合金涂层是由简单的FCC+BCC双相混合结构组成,Co含量的改变对涂层相组织的数量影响不大;随着Co含量的增加,合金涂层中显微组织的枝晶数目增加,并且得到明显粗化,通过面扫得显微组织中枝晶内富集Fe,Cr,Co元素,枝晶间富集Cu元素,Al均匀的分布在整个涂层中;随着Co含量的增加,硬度先增加后减小,在Co=1时合金涂层硬度达到最大为555.6HV;合金涂层中最小的摩擦系数为0.361;在3.5wt.%NaCl腐蚀介质中,合金涂层相比与45_^#钢基体具有较正的自腐蚀电位(E_corr=-0.325V),说明涂层耐腐蚀性比基体好。     

铁单元素基合金表面激光高熵合金化涂层的制备

利用高功率半导体激光器进行合金化处理,采用等摩尔比的Co,Cr,Al,Cu四主元合金粉末,在Fe单元素基合金Q235钢表面成功制备出FeCoCrAlCu激光高熵合金化涂层.利用SEM,XRD,EDS及显微硬度计对FeCoCrAlCu激光高熵合金化层的微观组织形貌、相结构、成分分布及性能进行系统研究.结果表明:Q235基材主元素Fe在激光辐照时参与了表面合金化过程,形成了FeCoCrAlCu五主元高熵合金涂层;合金化层相组成为具有简单bcc结构的固溶体,显微组织为典型的枝晶组织;激光高熵合金化层仅在基体界面附近出现了少量s四方结构中间相,从高熵合金化层表面到基材,体系的混合熵呈高熵-中熵-低熵梯度变化;FeCoCrAlCu激光高熵合金化涂层的显微硬度高达8.3 GPa,为基材Q253钢的3倍以上.     

真空烧结熔覆Ni60涂层的组织和性能

利用真空烧结熔覆技术在Q235钢基体上制备Ni60涂层,并对Ni60涂层的显微组织、硬度、耐磨性和耐腐蚀性进行分析。结果表明:Ni60涂层主要由γ-(Ni,Fe)、CrB和Cr_(23)C_6等相组成,涂层与基体界面处冶金结合良好;涂层的表面硬度为58.3 HRC,横截面上自表面到基体的硬度自676 HV0.2到220 HV0.2呈梯度分布;涂层的耐磨性为Q235钢的21.7倍,磨损机制为轻微的塑性切削和硬质相的脆性剥落;涂层的耐腐蚀性明显优于基体。     

Ti含量对氩弧熔覆CoCrFeNiCuTix高熵合金涂层组织及性能的影响

采用氩弧熔覆技术在Q235钢基体表面制备了CoCrFeNiCuTi_x(x表示摩尔比值,x=0、0.3、0.5、0.8和1)高熵合金涂层,研究了Ti含量对CoCrFeNiCuTi_x高熵合金微观结构和力学性能的影响。结果表明,不同Ti含量的CoCrFeNiCuTi_x高熵合金均为FCC单相固溶体。CoCrFeNiCu合金的微观组织为柱状晶结构。随着Ti的加入,微观组织中开始出现析出相,且Ti含量越高,析出相越多。同时Ti的加入明显提高了合金的显微硬度,当Ti的摩尔比为1时,涂层的截面显微硬度值达到最高值439.54 HV0.1。Ti对CoCrFeNiCuTi_x高熵合金的耐磨性具有显著影响,CoCrFeNiCuTi合金表现出最好的耐磨性。随着Ti含量的升高,合金的磨损机理由黏着磨损转化成黏着磨损与氧化磨损并存。     

激光熔覆工艺对高熵合金组织与性能影响

为了探究激光熔覆工艺对高熵合金组织和性能的影响,使用激光熔覆技术在Q235基材表面制备不同熔覆工艺下的高熵合金涂层.利用光学显微镜(OM)、扫描电子显微镜(SEM)、能谱仪(EDS)、X射线衍射仪等对高熵合金涂层进行显微组织形貌的观察及物相分析;利用显微硬度计、摩擦磨损试验机对涂层的硬度及耐磨性进行研究.结果表明,宏观形貌上,扫描速度一定时,激光功率增大,涂层宽度增加,涂层表面更加平整;激光功率一定时,扫描速度增加,熔覆层的宽度减小,相结构主要由体心立方(BCC)和面心立方(FCC)组成,扫描速度的增大或激光功率的降低,涂层中的晶粒变细小,且部分区域的胞状晶有向树枝晶生长的趋势,涂层硬度明显高于基材,最高可以达到553 HV,耐磨性要优于基体.     

热丝激光熔覆17–4PH涂层组织与腐蚀磨损性能

目的 在低碳钢表面高效制备沉淀硬化马氏体不锈钢涂层,研究涂层在腐蚀磨损苛刻条件下耦合损伤行为。方法 采用热丝激光熔覆技术在20钢基材表面制备17–4PH马氏体不锈钢涂层,通过X射线衍射仪(XRD)、扫描电子显微镜(SEM)等分析涂层的相组成和显微组织,采用电化学腐蚀摩擦磨损试验仪对涂层的摩擦磨损、极化曲线、电化学阻抗谱(EIS)及腐蚀磨损耦合行为进行研究。结果 制备的涂层组织均匀、致密,无裂纹、气孔等缺陷,主要由马氏体相组成。熔覆区的平均硬度约为310HV0.1,约是基材硬度的1.5倍,自腐蚀电流密度为6.583×10^?8 A/cm²,具有优异的耐蚀性。在3.5%NaCl溶液中,随摩擦载荷的增加,涂层的开路电位下降,摩擦因数增大,自腐蚀电位下降,腐蚀电流密度增大,摩擦对腐蚀促进作用明显。结论 热材激光熔覆技术节能、高效,制备的17–4PH涂层结构致密、性能优异,可用于在腐蚀磨损苛刻环境下零部件的表面改性。     

TiC增强高熵合金复合涂层的显微组织与摩擦磨损性能

采用激光熔覆技术在Q235钢表面制备了AlCoCrFeNi高熵合金涂层和AlCoCrFeNi-TiC复合涂层,采用X射线衍射仪(XRD)、扫描电镜(SEM)和能谱分析仪(EDS)表征了两种涂层的相结构和显微组织,采用维氏硬度计以及摩擦磨损试验测试了涂层的硬度和摩擦磨损性能,研究了 TiC对AlCoCrFeNi高熵合金涂...     

原位合成Ti(CN)/Fe复合涂层及耐磨耐蚀性能

采用反应氮弧熔覆技术在Q235A钢试件表面原位合成了Ti(CN)/Fe金属陶瓷复合涂层。利用扫描电镜、XRD射线衍射仪、显微硬度计、摩擦磨损试验机、电化学工作站分析了涂层形貌、涂层物相、涂层显微硬度及其耐磨耐蚀性能,并与Q235A钢进行了硬度、耐磨耐蚀对比试验。结果表明:涂层主要由Ti(CN)、Fe及少量的TiO2相组成,Ti(CN)呈细小颗粒状,涂层为良好的冶金结合;与Q235A钢相比,硬度提高了约3倍,摩擦系数约为Q235A的2/3,磨损量约为Q235A的1/2;在5%H2SO4溶液中,Ti(CN)涂层的腐蚀速率约为Q235A的1/3,在3.5%NaCl溶液中,Ti(CN)涂层的腐蚀速率约为Q235A钢的1/4。     

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.     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

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.     

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.     

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.     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

An Easy Way to Quantify the Adhesion Energy of Nanostructured Cu/X(X=Cr,Ta,Mo,Nb,Zr) Multilayer Films Adherent to Polyimide Substrates

An approach based on film buckling under simple uniaxial tensile testing was utilized in this paper to quantitatively estimate the interfacial energy of the nanostructured multilayer films(NMFs) adherent to flexible substrates. The interfacial energies of polyimide-supported NMFs are determined to be *5.0 J/m2 for Cu/Cr, *4.1 J/m2 for Cu/Ta,*2.8 J/m2 for Cu/Mo, *1.1 J/m2 for Cu/Nb, and *1.2 J/m2 for Cu/Zr NMFs. Furthermore, a linear relationship between the adhesion energy and the interfacial shear strength is clearly demonstrated for the Cu-based NMFs, which is highly indicative of the applicability and reliability of the modified models.     

High-Speed Friction Stir Welding of SiC_p/Al–Mg–Si–Cu Composite

A 17 vol% SiCp/Al–Mg–Si–Cu composite plate with a thickness of 3 mm was successfully friction stir welded(FSWed) at a very high welding speed of 2000 mm/min for the first time. Microstructural observation indicated that the coarsening of the precipitates was greatly inhibited in the heat-affected zone of the FSW joint at high welding speed, due to the significantly reduced peak temperature and duration at high temperature. Therefore, prominent enhancement of the hardness was achieved at the lowest hardness zone of the FSW joint at this high welding speed, which was similar to that of the nugget zone. Furthermore, the ultimate tensile strength of the joint was as high as 369 MPa, which was much higher than that obtained at low welding speed of 100 mm/min(298 MPa). This study provides an effective method to weld aluminum matrix composite with superior quality and high welding efficiency.