TiNiNb合金热变形流变行为的研究

采用Gleeble-1500热模拟试验机对TiNiNb合金进行了高温压缩变形实验, 分析了该合金在变形温度为800～1050 ℃, 应变速率为0.01～10 s~(-1)条件下的变形行为及流变应力的变化规律. 结果表明, 流变应力受变形温度和应变速率显著影响, 流变应力随变形温度的升高和应变速率的降低而降低. 采用双曲正弦模型确定了该合金的变形激活能Q和应力指数n, 建立了相应的热变形本构关系.     

铜银合金线材载流摩擦磨损行为研究

在改造过的MS-T3000摩擦磨损试验机上,以黄铜为摩擦副对热型连铸技术制备的铜银合金线材进行载流摩擦磨损试验,研究了电流对铜银合金导线载流摩擦磨损行为的影响.结果表明,电流强度对铜银合金干摩擦磨损行为有显著影响.电流在0～15 A范围内,随着电流的增加,摩擦系数与磨损率变化基本一致,呈现先减少后增加的趋势.电流较小时,接触电阻也比较小且较稳定;电流高时,接触电阻比较大,波动剧烈,而且有电弧出现.铜银合金导线在带电条件下的主要磨损形式为磨粒磨损、粘着磨损以及以电化学作用为主的氧化磨损或腐蚀磨损.     

TC11钛合金等轴组织热变形行为与组织演变

采用等温恒应变速率压缩试验研究了TC11钛合金等轴组织两相区980～800℃,应变速率O.001～O.1 s-1,变形程度50%条件下的变形行为,分析了变形参数对应力-应变曲线、微观组织演变机制和规律的影响,建立了该合金两相区变形的热加工图,并采用EBSD技术测试了热变形组织的晶界特征.结果表明:(1)980℃变形,β相是主要变形相,O.001～O.1 s-1之间的功率耗散效率值在动态回复和再结晶范围内;α相经历了变形促进下的溶解(高应变速率)和聚集粗化(低应变速率)的过程,即α晶粒尺寸和相含量随着应变速率的加快明显减小.(2)950～900℃变形,O.001～O.01 s-1之间的功率耗散效率值在超塑性变形范围内;变形主要是软基体的β相和界面的变形行为;变形过程中,α晶粒尺寸和相含量基本不变.(3)850～800℃变形,α相是主要变形相,发生了连续动态再结晶过程;β相起晶界协调变形的作用.     

冲击磨损中合金结构钢的组织结构变化

利用自行研制的落球冲击磨损实验装置，在模拟球磨机的工矿条件下，研究了冲击磨损后样品的组织结构变化，实验结果发现，硬度较低的样品冲击磨损后产生了剧烈的塑性变形，甚至形成绝切的形变带，硬度较高的样品冲击磨损后得到了表面白层和亚表层白层，有时在样品表面下产生了白色块状组织，还利用透射电子显微镜观察了白层的形貌。     

Mg-Y-Nd-Zr合金加工工艺与组织演化的研究

对Mg-Y-Nd-Zr镁合金铸锭分别进行挤压和锻压变形加工，然后对变形加工件进行固溶、时效处理。采用金相显微镜、扫描电镜及能谱仪分析研究了该合金的组织演化过程。分别测试了铸造、挤压、锻压和热处理等不同状态下合金试样的室温和250℃力学性能。结果表明，该合金在350-400℃内进行挤压，组织发生完全动态再结晶，可以获得较好的力学性能；挤压后进行锻压变形，试样的室温抗拉强度和屈服强度分别比挤压状态提高13．5％和15％，延伸率下降33．3％；250℃的抗拉强度和屈服强度比挤压状态分别提高15％和41．4％。试样经过T6处理后，晶界附近析出相尺寸细小、分布均匀，室温抗拉强度和屈服强度分别达到365和335MPa。固溶强化和析出强化是导致T6状态试样拉伸强度提高的两个主要因素。     

Microstructure and Wear Behavior of Solidification Sonoprocessed B390 Hypereutectic Al-Si Alloy

The hypereutectic Al-Si alloys constitute an important family of alloys because of their excellent wear resistance and low thermal expansion. However, the optimal microstructure and hence the optimal service performance of these alloys cannot be achieved by the conventional melt treatments used in industry today, because of the chemical incompatibility between the primary-Si refiners and the eutectic-Si modifiers used in microstructure control. The current study aimed at using ultrasonic vibrations to improve the microstructure and the properties of these alloys. The results of the current study showed that for the B390 Al-Si alloy (i) the ultrasonic treatment has potential refining effect on the primary Si and Fe intermetallic phases, (ii) the primary Si particles become finer as the pouring temperature decreases from 1033 K (760 °C) to 938 K (665 °C), (iii) pouring and ultrasonic treatment at temperatures below the start of primary Si precipitation result in the coexistence of large and fine Si particles in microstructure, (iv) phosphorous additions of 50 ppm did not show any substantial effect in the ultrasonically treated ingots, (v) ultrasonic-treated samples have uniform hardness over the surface while the untreated samples show large scattering (high standard deviation) in hardness levels and (vi) ultrasonic-treated samples showed better wear resistance in the absence of phosphorous.     

Effect of Various Nanoparticles on Tribo-Layers and Wear Behavior of TC11 Alloy

Multilayer graphene (MLG), Fe₂O₃, and their nanocomposites with various proportions and amounts were applied as additives and directly participated in the formation of tribo-layers during sliding wear of TC11 alloy against AISI 52100 steel. Their ingredients and amounts were found to exert substantial effects on the additive-containing tribo-layers and wear behavior. Irrespective of the added amount of MLG or Fe₂O₃, the formed tribo-layers, because of the lack of load-bearing or lubricant capacity, readily lost stability and protection function, causing a high wear rate. However, a small quantity of MLG/Fe₂O₃ nanocomposites could result in a remarkable decrease in the wear rate. This was attributed to the stable existence and continuous protection of a friction-reduced and wear-resistant double-layer tribo-layer. In particular, Fe₂O₃-rich nanocomposite additives produced more protective tribo-layers to markedly improve the wear resistance of TC11 alloy.     

Wear Behavior at High Temperature of Dual-Particle Size Zircon-Sand-Reinforced Aluminum Alloy Composite

The basic aim of the present investigation is to study the role of particle size for high-temperature application of ZrSiO₄-reinforced aluminum-based LM13 alloy composite as a bearing material. Composites containing 15 wt pct ZrSiO₄ particles of two different size ranges (20 to 32 and 106 to 125 μm) in different proportion were prepared by the stir casting route. The microhardness measured at different areas indicates good interfacial bonding. Transition in the wear mode for all composites occurs after temperature 423 K (150 °C). The overall wear properties of DPS-2 composite containing 12 pct fine and 3 pct coarse particles are better at all temperatures for both low and high loads.     

片层组织TC17钛合金高温变形行为研究

通过热压缩试验研究了具有初始片层组织的TC17钛合金在780~860℃和应变速率0.001~10 s-1范围内的热变形行为和组织演变。分析了该合金在两相区变形的应力-应变曲线特征,其流变应力本构关系可以用双曲正弦方程和Zener-Hollomon参数描述,得到TC17合金在两相区变形的平均激活能为488.86 kJ.mol-1。显微组织分析发现:TC17合金在两相区变形时组织演变的主要特征是片层组织球化;热变形参数严重影响片层组织球化过程的进行,加大变形量、降低应变速率以及提高变形温度可以提高片状组织的动态球化程度。     

新型低合金铸态复相耐磨钢的组织与性能

开发了一种新型多元合金化铸态复相耐磨钢，化学成分（％）：0．30－0．45C，1．5－3．0Mn，0．8－1．5Cr，0．8－1．2Si，0．2－0．8Mo，0．10－0．25V，0．50－0．10Ti，0．005－0．012B，该新型耐磨钢为马氏体、下贝氏体加薄膜状残余奥氏体的复相组织，具有良好的冲击韧性。     

Effect of Cerium on Gas Evolution Behavior of Pb-Ca-Sn Alloy

Hydrogen and oxygen evolution reactions areharmful to the valve regulate lead acid battery duringcharging and discharging processes.Oxygen evolutionreaction occurs at the positive electrode in the leadacid battery and transfers from baffle to the negativeelectrode,reducing to water finally.Hydrogen evolu-tion reaction takes place occasionally on the negativeelectrode inthe lead acid battery.In general,the rateof hydrogen oxidation reaction on the negative elec-trode is lower or less hydrogenis…     

应力作用下Al-Li合金的腐蚀行为研究

通过测量动电位极化曲线,并用扫描电镜（SEM）、透射电镜（TEM）观察,分析应力作用下峰时效的2195、1420Al-Li合金在3．5％NaCl溶液中的腐蚀行为。结果表明,无应力时1420Al-Li合金发生蚀孔较大且不连续的均匀腐蚀,2195Al-Li合金发生局部腐蚀为晶间腐蚀和孔蚀的均匀腐蚀;施加应力时1420Al-Li合金蚀孔增多、尺寸减小,2195Al-Li合金晶间腐蚀加重,大量孔蚀连接成片形成严重的均匀腐蚀。     

TA15钛合金冷轧板材异常组织剖析

主要针对中试试验中TA15钛合金冷轧板材异常性非等轴组织形貌进行分析,为进一步稳定其轧制工艺及进行工业化生产提供帮助。     

激光熔敷Ni60／WC合金层的腐蚀磨损特性

研究了４５钢表面激光熔敷镍基ＷＣ合金层的耐蚀性及在不同冲击速度和不同浓度酸性介质下的腐蚀磨损特性。结果表明，激光熔敷Ｎｉ６０／ＷＣ合金层不论耐蚀性还是抗腐蚀磨损性能同于２Ｃｒ１３不锈钢。应用微机对试验结果进行逐步回归分析，得出了影响因素与腐蚀磨损速度的害量关系，并探讨了熔敷层的腐蚀磨损过程。     

合金成分与组织结构对铝合金阳极氧化的影响

本文叙述合金化元素、杂质元素及显微结构对铝合金阳极氧化的影响，介绍熔铸、热处理、加工成型及化学预处理等工艺参数对阳极氧化的作用。     

钨合金冲击韧性随温度变化的演变规律及断裂方式研究

选用粉末冶金法制备93W-5Ni-2Fe合金,通过低温冲击韧性试验测试合金在常温到-60℃之间的冲击韧性,探索材料在低温环境下冲击韧性演变规律,通过扫描电镜观察低温冲击韧性断口,研究材料在低温环境下的断裂机制演变规律.结果表明:93WNiFe合金材料随着材料环境温度的降低,材料的冲击韧性开始基本维持不变,当环境温度低于...     

Microstructural Evolution and Solidification Behavior of Al-Mg-Si Alloy in High-Pressure Die Casting

Microstructural evolution and solidification behavior of Al-5 wt pct Mg-1.5 wt pct Si-0.6 wt pct Mn-0.2 wt pct Ti alloy have been investigated using high-pressure die casting. Solidification commences with the formation of primary α-Al phase in the shot sleeve and is completed in the die cavity. The average size of dendrites and fragmented dendrites of the primary α-Al phase formed in the shot sleeve is 43 μm, and the globular primary α-Al grains formed inside the die cavity is at a size of 7.5 μm. Solidification inside the die cavity also forms the lamellar Al-Mg₂Si eutectic phase and the Fe-rich intermetallics. The size of the eutectic cells is about 10 μm, in which the lamellar α-Al phase is 0.41 μm thick. The Fe-rich intermetallic compound exhibits a compact morphology and is less than 2 μm with a composition of 1.62 at. pct Si, 3.94 at. pct Fe, and 2.31 at. pct Mn. A solute-enriched circular band is always observed parallel to the surface of the casting. The band zone separates the outer skin region from the central region of the casting. The solute concentration is consistent in the skin region and shows a general drop toward the center inside the band for Mg and Si. The peak of the solute enrichment in the band zone is much higher than the nominal composition of the alloy. The die casting exhibits a combination of brittle and ductile fracture. There is no significant difference on the fracture morphology in the three regions. The band zone is not significantly detrimental in terms of the fracture mechanism in the die casting. Calculations using the Mullins and Sekerka stability criterion reveal that the solidification of the primary α-Al phase inside the die cavity has been completed before the spherical α-Al globules begin to lose their stability, but the α-Al grains formed in the shot sleeve exceed the limit of spherical growth and therefore exhibit a dendritic morphology.