纳米Y_2O_3弥散强化Ni基合金激光熔覆层

研究了纳米Y2O3对Ni基合金激光熔覆层显微组织、相结构和性能的影响。结果表明:加入纳米Y2O3 的Ni基激光熔覆层出现大量细小、无方向性生长的等轴晶;熔覆层主相为γ-Ni,此外还有Cr23C6、Ni4.6Si2B和 Ni17Y2等;加入1．5％纳米Y2O3的熔覆层显微硬度值大幅度提高,其耐磨性比纯Ni基提高5倍多,磨损机理由较为严重的粘着磨损转变为微动磨损。     

纳米CeO2/Ni基合金复合材料激光熔覆层组织与耐磨性

利用5 kW CO2激光器,在Q235低碳钢表面熔覆微米或纳米CeO2/Ni基合金复合材料,制备了涂层.利用光学显微镜、扫描电镜和X射线衍射仪分析比较了熔覆层的组织、磨损彤貌及相结构,利用MM-200环-块式滑动磨损机检测了熔覆层的耐磨性.结果表明:熔覆层的主要相为γ-Ni和Cr23C6以及CeNi5,Ni3Si和Ni3B等;加入微米Ce02的Ni基激光熔覆层组织明显细化,并有大量的放射状等轴晶;加入纳米CeO2的Ni基激光熔覆层出现大量更加细小的等轴晶,并且组织致密.含纳米CeO2的Ni基熔覆层与纯Ni基的相比,耐磨性大幅度提高,磨损机理由黏着磨损转变为微动磨损.     

激光熔覆纳米Sm2O3颗粒增强Ni基合金涂层

利用5 kWCO2激光器,在Q235低碳钢表面熔覆微米或纳米Sm2O3/Ni基合金复合材料,制备了涂层.利用光学显微镜、扫描电镜和X射线衍射仪,比较分析了熔覆层的组织及相结构,利用显微硬度计和MM 200型环-块滑动磨损机检测了熔覆层的硬度和耐磨性.结果表明,熔覆层的主要相为γ-Ni和Cr23C6,且出现了Fe7Sm,Ni3Si和Ni3B;加入稀土氧化物熔覆层的冶金结合区白亮带变窄;加入纳米Sm2O3不仅细化了熔覆层的组织,而且形成了大量的等轴晶;加纳米Sm2O3比微米Sm2O3的熔覆层的显微硬度和相对耐磨性大幅度提高,磨损机理由磨粒磨损和黏着磨损转变为微动磨损.     

纳米Y2O3-Co基合金激光熔覆复合涂层的分析

采用纳米Y2O3和Co基合金粉末,并利用激光表面熔覆技术和堆焊技术在Ni基合金基体上制备了纳米Y2O3-Co基合金复合涂层.运用扫描电镜(SEM)等测试方法,研究了复合涂层的显微组织和显微硬度,通过磨损试验和腐蚀试验分析了激光熔覆涂层和单一堆焊层的耐磨性和耐蚀性.结果表明,激光熔覆层显微组织由熔合区、细等轴状枝晶区及粗枝晶区构成;激光熔覆层的显微硬度由堆焊层的512.8 HV提高到868.9HV;激光熔覆层的耐磨性提高了51.2倍,40 min磨损量由堆焊层的25.6 mg降低到激光熔覆层的0.5 mg;激光熔覆层在10%HCl、10% HNO3和10% NaOH中的耐腐蚀性均比堆焊表面有明显改善.     

Ti811合金表面激光熔覆涂层微观组织及性能研究

目的研究Ti811合金表面激光熔覆涂层的微观组织及磨损性能。方法利用激光熔覆技术,在Ti811合金表面激光熔覆原位合成了Ti C+Ti B2增强镍基复合涂层。利用X射线衍射仪(XRD)、扫描电镜(SEM)、电子探针(EPMA)、显微硬度计和摩擦磨损试验机,系统地研究了熔覆层的物相组成、显微组织、显微硬度及摩擦磨损性能,并利用二维点阵错配度理论对Ti C的细化机理进行分析。结果激光熔覆涂层与基体呈良好的冶金结合,熔覆层生成物相主要由Ti C、Ti B2、Ti2Ni和γ-Ni组成,其中Ti C呈等轴枝晶状和花瓣状,Y2O3的(111)面与Ti C的(110)面之间的二维点阵错配度为6.813%,Y2O3作为Ti C的非均质形核核心为中等有效。熔覆层的平均显微硬度为913.93HV0.5,约为基体Ti811硬度的2.4倍。熔覆层摩擦系数稳定在0.45～0.52之间,磨损机理主要为粘着磨损与磨粒磨损。结论采用激光熔覆技术能够在Ti811合金表面成功制备Ni基复合增强涂层。熔覆层中Y2O3颗粒具有细晶强化、弥散强化、增加形核率的作用,熔覆层具有较高的显微硬度与良好的耐磨损性能。     

In2O3对Ni60激光熔覆层的影响

向Ni60合金粉末中加入适量的In2O3选取合适的工艺参数，采用激光熔覆技术在45钢表面上获得了无裂纹的高质量熔覆层。对熔覆层显微组织进行了观察和分析，测试了熔覆层的显微硬度和摩擦磨损性能。结果表明，同未加入In2O3的Ni60激光熔覆层相比，加入适当比例In2O3的Ni60熔覆层，虽然硬度有所降低，但硬度分布更加均匀，且在该文摩擦条件下耐磨性提高。In2O3能够降低Ni60激光熔覆层裂纹敏感性的原因在于适量的In2O3能够抑制粗大块状硬质相的生长，改善枝晶分布，细化组织晶粒，提高涂层韧性。     

激光表面熔覆制备ODS Ni基高温合金涂层的凝固组织

采用横流CO2激光，在Ni基高温合金表面制备了纳米Al2O3弥散强化(ODS)Ni基合金熔覆层。利用光学显微镜、扫描电镜及EDS附件分析了熔覆层的组织结构。结果表明：界面晶粒的生长方向为垂直于界面的“外延式”生长；加入纳米Al2O3，界面的生长形态发生变化，由细长的柱状树枝晶转变为较短的树枝晶；纳米Al2O3含量增大至1％时整个断面获得等轴枝晶组织；纳米Al2O3作为异质形核的核心，细化了组织。     

La2O3对激光熔覆镍基碳化钛复合涂层组织和耐腐蚀性能的影响

在45钢基材表面进行加入Ni60+30wt%镍包碳化钛合金粉末的激光熔覆,研究了La2O3,含量和激光功率对激光熔覆层的显微组织、裂纹情况及耐腐蚀性能的影响.结果表明:适量La2O3的加入能使镍基碳化钛金属陶瓷熔覆层组织细化,裂纹大为减少甚至消失,宏观质量得到明显改善.添加适量La2O3,的激光熔覆层的耐腐蚀能力比不含La2O3的激光熔覆层要高.     

基于稀土调控的激光熔覆Ni60强化铝合金的高温摩擦磨损性能研究

目的 提高铝合金的综合使用性能。方法 采用激光熔覆技术对6063铝合金表面分别进行了Ni60、Ni60+4%CeO2、Ni60+5%Y2O3和Ni60+5%La2O3激光熔覆处理,然后进行了硬度和高温摩擦磨损实验,通过分析各试样的摩擦系数、磨痕轮廓、磨损量、物相、成分和磨损后微观形貌,进而分析各试样的耐磨性能和磨损机理,以及稀土对熔覆层耐磨性能和磨损机理的影响。结果 熔覆层的硬度呈梯度分布,加入稀土Ni60熔覆层的硬度明显提升。6063铝合金随着载荷和磨损温度的升高,磨损机制从二体磨粒磨损,到粘着磨损,再到严重的熔融磨损和氧化磨损,由轻微向严重磨损转变。Ni60熔覆层的磨损机制主要为剥层磨损、氧化磨损和轻微的犁削磨损,并随着载荷和磨损温度的升高,剥层磨损的程度越来越严重。添加最佳稀土含量的熔覆层随着载荷和磨损温度的升高,磨损机制逐渐由以犁削磨损为主过渡为以剥层磨损为主,并含有氧化磨损和犁削磨损。与Ni60熔覆层相比,加入最佳稀土含量的熔覆层的高温摩擦磨损性能均有明显提高。结论 对比三种稀土熔覆层,高温摩擦磨损性能由好到差的顺序为Ni60+4%CeO2熔覆层>Ni60+5%Y2O3熔覆层>Ni60+5%La2O3熔覆层。     

Cr12MoV模具钢激光熔覆Ni基、Co基合金的组织与性能

利用5kW的横流CO2激光器在Cr12MoV钢表面分别熔覆Stellie6和Ni60合金粉末，并利用X射线衍射、光学显微镜分析了合金熔覆层的金相组织和相组成；测量了合金熔覆层的显微硬度，并用M-200环-块磨损试验机研究了其磨损性能。结果表明，激光处理层存在熔覆区、结合区和基体热影响区三个区域。由于基材为淬火组织，故在热影响区中存在二次淬火区和回火区，最高硬度存在于二次淬火区。Stellie6合金熔覆层由枝晶Co基固溶体及Cr23C6、Cr7C3和CoCx碳化物、WC等相组成；Ni60合金熔覆层由Ni基固溶体及NiCrFe相、γ-Fe基固溶体、Cr23C6、Cr7C3型碳化物和Cr2B硼化物等相所组成。Ni60合金熔覆层比Stellie6合金熔覆层具有更高的硬度，Ni60熔覆层的耐磨性要比Stillite6熔覆层好。     

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.