鞍形弹性垫圈断裂原因分析

通过对断裂铍青铜鞍形弹性垫圈断口进行宏观微观观察、金相组织检查、硬度测试等理化分析,以及对同批次原材料进行组织检验分析断裂原因。结果表明:断裂垫圈断口呈沿晶韧性断裂特征,主要是硬度偏技术要求上限,增加了材料的脆性引起断裂,并提出了相应改进措施。     

焊后热处理对AZ31B镁合金自动TIG焊焊接接头的影响

利用六轴机器人夹持氩弧焊枪对AZ31B变形镁合金进行了平板对焊,探讨了焊后热处理对焊接接头微观组织、第二相及力学性能的影响规律。结果表明,焊后热处理有效改善了焊接接头的微观组织,大幅提升了焊接接头的力学性能。焊后热处理后,焊接接头微观组织中晶粒尺寸没有太大改变,但沿晶界分布的第二相数量明显减少,焊接接头的抗拉强度和伸长率分别达到了母材的97.8%和84.5%。未经热处理的拉伸样品是在焊缝处断裂,断口呈现出典型脆性断裂特征;而热处理之后的拉伸则是在热影响区断裂,断口呈现出准解理偏韧性的混合断裂特征。     

三种航空发动机供油系统典型部件的气蚀

为了研究航空发动机供油系统部件的气蚀失效机制与规律,分析了航空发动机供油系统中三种典型合金(TC6钛合金、ZL101铝合金、2Cr3WMoV钢)部件的气蚀原因,并比较了其气蚀特点.研究表明,在航空煤油介质中,材料强度和微观组织对气蚀破坏的微观行为有较大影响.三种合金中都广泛存在气蚀的相选择性行为,即那些较软易变形的或韧性较差的相通常较另一相优先被气蚀,使材料表面的整体强度下降,从而导致材料破坏的加剧.另外在航空发动机供油系统中冲蚀常伴随气蚀同时发生,常见的气蚀损伤多为"冲蚀-气蚀"复合机制所致.     

冲击载荷下AZ31镁合金的断裂行为

采用霍普金森压杆技术对AZ31镁合金进行室温下应变速率为1 000~3 000s-1的高速冲击,利用光学显微镜和扫描电镜对断裂试样的微观组织和断口形貌进行分析。结果表明,随着应变速率的增加,材料的断裂趋势增加,材料主要表现为沿晶断裂和穿晶断裂的混合断裂方式,断口形貌具有典型的准解理断裂特征;孪晶和晶粒边界是裂纹扩展源,孪生和裂纹在变形过程中存在竞争关系。     

浮头式换热器连接螺栓失效分析

从断口宏观特征、材质、断口电镜、硬度以及微观组织等方面对换热器内紧固螺栓断裂进行了分析。结果表明,螺栓材料铬含量偏低并发生敏化,导致抗腐蚀性能降低,在环境介质的交互作用下发生晶间应力腐蚀开裂,最终导致断裂。     

Al—7Si—0.45Mg铸造合金断裂韧性统计模型

本文根据Al-7Si-0.45Mg铸造合金断裂微观特征的观察、对合金各种力学性能的测量和影响因素的分析以及对由此分析得出的该合金断裂组织控制参量——较大共晶Si粒子的线尺寸及其分布的观察和定量研究,提出了符合该合金断裂过程的微观断裂机理,并把该合金断裂的组织控制参量与断裂性能相联系,在铸造合金中建立了符合合金微观断裂机理的断裂统计模型。     

航空铝合金自冲铆接接头微观失效研究

采用自冲铆接技术实现了2A12和6061航空铝合金薄板材料的有效连接,通过进行拉伸-剪切测试,从宏观层面分析了接头静失效形式,从微观层面研究了接头拉脱失效和基板断裂失效机理。结果表明：航空铝合金自冲铆接接头的主要静失效形式为拉脱失效,并有接头伴随纽扣脱落现象,同时有上板断裂和下板断裂的失效形式出现。对拉脱失效机理进行分析,从宏观上发现接头有明显的刮蹭和大幅的塑性形变;从微观上发现,上板的断裂失效机理为沿晶断裂和局部显微孔洞聚集,下板的断裂失效机理为板材上下边缘区域以剪切断裂为主、靠近试样厚度中心区域以微孔洞聚集型正断为主。     

孔隙率对Ti-Al金属间化合物多孔材料拉伸性能的影响

采用元素混合粉偏扩散-反应合成-粉末烧结方法制备了Ti-Al金属间化合物多孔材料,对其进行了拉伸试验研究,分析其拉伸变形特征,揭示出孔隙率对拉伸性能的影响规律以及拉伸断裂微观机理。结果表明:Ti-Al多孔材料的拉伸应力-应变曲线大致可分为弹性、屈服、强化和破坏4个阶段,无颈缩现象;力学性能指标(如弹性模量、屈服极限和强度极限等)均随孔隙率的增大而减小,延伸率远低于5%,呈现出明显的室温脆性;断口特征宏观上表现为脆性断裂,微观上同时存在穿晶断裂与沿晶断裂,其断裂机理与Ti-Al金属间化合物致密体的显微组织密切相关。     

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针对用40Cr钢制造的重载车轮轴在试车过程中的断裂,具体分析了其宏观和微观断口形态以及轮轴各部位的显微组织特征等,特别就车轮轴断裂性质及其本质原因进行了相关分析和讨论。最终认为：轮轴的断裂属典型的旋转弯曲疲劳断裂,疲劳起源于轮轴根部。轮轴根部表面未经淬火,同时存在磨损条带和表面微裂纹,是导致了轮轴疲劳断裂的主要原因。     

Al2O3/Cu复合材料的高温拉伸性能研究

Al2O3弥散强化铜复合材料(ADSCC)因其具有优良的高强度高导电性能以及抗高温软化性能而成为备受瞩目的一种工程材料.研究了ADSCC的微观组织和拉伸性能.研究表明该材料相比Cu-Cr合金(Cr0.7%)在高温下具有很高的强度保持比.材料的强度随温度的升高而下降.对ADSCC的微观组织研究表明该材料的强度高主要是因为Al2O3颗粒的弥散分布限制了位错运动,阻碍了晶粒长大和Cu基体的再结晶.动态回复和局部再结晶是主要的软化机制.断裂特征表现为局部韧性断裂.     

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。     

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.     

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.     

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.     

A STUDY OF TEMPERATURE-DEPENDENT VALENCE BOND STRUCTURE OF TITANIUM

On the basis of energy and shape method for the determination of the valence bond (VB) structures of crystal, the valence bond structure of titanium is redetermined at room temperature and calculated in the whole temperature range of 0-1943K. The outer shell electronic distribution of Ti is e_c~(2.9907) · (s_c~(0.4980) d_c~(2.4927)) ef1.0093 in crystal. The temperature dependences of the VB structures of hcp and bcc phases are the same. The VB structures of hcp and bcc phases monotonically increase or decrease with the increase in temperature, but show discontinuous changes at the phase-transformation temperature 1155K.