铜晶体的疲劳损伤微观机制

对Cu单晶体、双晶体和多晶体疲劳损伤微观机制的总结结果表明：在中、低应变范围Cu单晶体的疲劳裂纹主要沿驻留滑移带萌生,而在高应变范围则沿粗大形变带萌生;Cu双晶体中疲劳裂纹总是优先沿大角度晶界萌生和扩展,而小角度晶界则不萌生疲劳裂纹;对于Cu多晶体,疲劳裂纹主要沿大角度晶界萌生,有时也沿驻留滑移带萌生,而孪晶界面两侧由于滑移系具有相容的变形特征而未观察到疲劳裂纹萌生．     

Al双晶体的晶界疲劳效应SCIEI

通过Al双晶体疲劳试验,研究了晶界对循环变形和疲劳裂纹扩展的影响。实验结果表明,晶界疲劳效应集中体现于晶界影响区,表现为不相容塑性应变在该区内产生内应力,并由此可激发次级滑移,甚至产生晶界裂纹;在常幅循环应力下,随超Ⅰ阶段裂纹逐渐接近晶界,裂纹分叉、前沿碎裂,扩展速率降低,直至在晶界影响区中央达到一最小值。本文提出了晶界诱发裂纹顶端屏蔽机制,并以此解释了上述超Ⅰ阶段裂纹对微观组织敏感的扩展行为。     

金属材料疲劳损伤的界面效应

总结了不同金属材料在低周疲劳过程中典型的晶界、孪晶界、相界和微电子互连界面的损伤开裂行为. 纯Cu中疲劳裂纹萌生的难易顺序为: 小角度晶界、驻留滑移带和大角度晶界. 对于纯Cu与铜合金中退火孪晶界, 是否萌生疲劳裂纹与合金成分有关, 随合金元素的加入降低了层错能, 退火孪晶界相对容易萌生疲劳裂纹. 对于Cu--Ag二元合金, 由于存在不同的晶界和相界面, 是否萌生疲劳裂纹取决于界面两侧晶体的取向差, 通常两侧取向差大的界面容易萌生疲劳裂纹. 在微电子互连界面中, 疲劳裂纹萌生位置与焊料成分和时效时间有关,对于Sn--Ag/Cu互连界面, 疲劳裂纹通常沿焊料与界面化合物结合处萌生; 对于Sn--Bi/Cu互连界面, 随时效时间增加会出现明显的由于Bi元素偏聚造成的界面脆性.     

铜双晶体中晶界及组元晶体的疲劳寿命

本文对具有单,双滑移取向组元晶体的近生趣晶界铜双晶体进行拉－拉循环变形,得出铜双晶体中晶界及组元晶体的Ｓ－Ｎ曲线,比较了铜双晶体晶界及组元晶体疲劳寿命的差别,发现在相同的应力幅下晶界的疲劳寿命明显低于组元晶体的疲劳寿命。     

不同应力状态下6063铝合金断裂机制原位拉伸研究

用SEM-520原位拉伸实验对可以实现不同应力的6063铝合金试件的断裂过程做了详细研究和分析.研究结果表明:不同应力状态下的铝合金试样在拉伸过程在其表面上都产生了大量的滑移带,但断裂机制不同.随着三轴应力度的降低,断裂从正断向剪断过渡,试件断口也由韧窝断裂模式向剪切断裂模式演变;6063铝合金晶界是其最薄弱环节,大量微裂纹产生于晶界,随着载荷的增加,微裂纹长大和扩展,与此同时,在局部变形带中沿晶界和滑移带又产生了新的微裂纹,微裂纹之间通过扩展或剪切而连接导致试样断裂;试样最小截面上的三轴应力度越小,试样断口的2个面上韧窝的取向越明显,而且断口越光滑.     

EFFECT OF ZIGZAG GRAIN BOUNDARY ON CREEP RUPTURE OF A 10Cr-15Co-Ni-BASE WROUGHT SUPERALLOY

应用两种热处理制度分别获得弯曲晶界和平直晶界,研究两种晶界状态对10Cr-15Co-Ni基变形高温合金蠕变断裂过程的影响,重点探讨弯曲晶界改善合金热强性原因。研究表明,弯曲晶界对裂纹的萌生、长大及扩展,对裂纹的形态及断裂方式,都有显著的影响。弯曲晶界能有力地阻止晶界滑动及推迟裂纹连接,使晶内参与更多的变形,弯晶的主要作用体现在蠕变第三阶段。合金经弯晶处理后蠕变断裂寿命提高26％。     

弯曲晶界对10Cr-15Co-Ni基变形高温合金蠕变断裂的影响

应用两种热处理制度分别获得弯曲晶界和平直晶界,研究两种晶界状态对10Cr-15Co-Ni基变形高温合金蠕变断裂过程的影响,重点探讨弯曲晶界改善合金热强性原因。研究表明,弯曲晶界对裂纹的萌生、长大及扩展,对裂纹的形态及断裂方式,都有显著的影响。弯曲晶界能有力地阻止晶界滑动及推迟裂纹连接,使晶内参与更多的变形,弯晶的主要作用体现在蠕变第三阶段。合金经弯晶处理后蠕变断裂寿命提高26％。     

不同应力状态下铝合金变形及损伤机理的研究

利用改装的Arcan夹具对铝合金（6063）的蝶形试样进行0°，30°，45°，60°，90°的拉伸及拉伸卸载试验，研究了铝合金在不同应力状态下变形及损伤机理。结果表明：铝合金在不同应力状态下的工程应力一应变曲线明显不同。0°加载时，在蝶形中心产生微孔洞，微孔洞之间剪切，从而产生了微裂纹。随着微裂纹的扩展、连接导致试样断裂。随着试样中三轴应力度的减小，在蝶形试样中心的剪切应力不断增大，同时在蝶形试样中的剪切变形带越来越集中。显微裂纹首先在剪切带中产生，随着微裂纹的扩展导致试样的断裂。90°拉伸时，在蝶形中心形成明显的剪切变形带。90°加载时，在试样中产生的剪切带是形变剪切带而非相变剪切带。利用有限元软件ABAQUS对不同角度拉伸试验进行模拟，从而得出了不同应力状态下的塑性区的形状和大小。     

热轧参数对铸态AZ91镁合金组织与性能的影响

通过不同道次压下量和轧制道次的热轧成形实验,研究了不同变形条件对AZ91铸态镁合金组织和析出相演变的影响,以及合金在热轧变形中的开裂行为。实验结果表明:对AZ91镁合金多道次、小压下量轧制是实现其累积大塑性变形的途径之一。在实验轧制条件下,AZ91镁合金塑性变形仍以孪生变形为主,动态再结晶并未明显进行,仅在晶界及析出相附近发生部分不连续动态再结晶。轧制变形过程中,β-Mg_(17)Al_(12)相呈短条棒状或颗粒状分布于晶界附近,且尺寸更为细小。在晶界附近分布的脆性析出相成为微裂纹萌生的源头,随着累积变形量的增加,部分Mg_(17)Al_(12)相被轧碎形成二次裂纹,裂纹进一步沿晶界扩展,造成明显开裂现象。     

海洋柔性立管用钢的疲劳断裂行为

采用GPS100高频疲劳试验机研究了海洋柔性立管用钢在温轧工艺下的疲劳断裂行为。结果表明,海洋柔性立管用钢疲劳寿命随加载应力幅的升高而不断下降;疲劳裂纹产生于试样表面,裂纹源区可见变形带及河流花样,裂纹扩展区存在大量二次裂纹,瞬断区疲劳裂纹呈韧性断裂特征。在疲劳裂纹扩展过程中,裂纹的扩展能力因大角度晶界的铁素体和高强度贝氏体的相互作用而受到限制,同时在晶界处形成的二次裂纹同样可减缓扩展速率,达到提高疲劳寿命的效果。     

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.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

The Mirror with Patterns of Auspicious Animals and Grapes——Exquisite cast mirror and the technology of surface tin-enrichment by rubbing-in and infiltration of tin-rich powder

<正>Bronze mirrors were used by the Chinese people before the introduction of the glass mirror.Only after it was replaced by the glass mirror did the bronze mirror gradually retreat from people's lives.Different styles of bronze mirrors were made in different historical periods,particularly in the Warring States Period,the Han and Tang Dynasties,which were the three peaks of the development of bronze mirror arts in ancient China.The casting techniques were exquisite.The surface of the bronze mirror was smooth and bright enough to reflect one's image,and there were scarcely any casting defects on the mirror surface.On the back of the bronze mirror,there were rich depictions of Arts and Humanities,and the ornamentations were also     

The 9th China International Diecasting Congress & Exhibition

The 9th China International Diecasting Congress ＆ Exhibition was held on July 22-24, 2014 at Shanghai New International Expc Centre. This exhibition was the most successful over the years, with over 6890 visitors and 155 exhibitors, and the exhibition area increased by 30% from 9,500 square meters in 2012 to 12340 square meters. Die casting enterprises from a total of 24 countries and regions, including China mainland, Chinese Taiwan and Hong Kong, South Korea, Japan, Germany, India, Thailand, Malaysia, the United States, Russia, Australia, Iran, Ukraine, Brazil, Colombia, Singapore, Austria, Canada, Croatia, France, Turkey, United Kingdom, Vietnam, attended the congress and exhibition.     

Introduction of the Fluid Control Engineering Institute of Kunming University of Science and Technology

正The Fluid Control Engineering Institute of Kunming University of Science and Technology was set up in 1996.The researches of institute concentrate on electro-hydraulic(pneumatic)servo/proportional control and hydromechatronics.The Institute is committed to research and development of electro-hydraulic control of high-end technical equipment in ferrous metallurgy refining produc-     

RARE METALS Volume Contents

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Antimony Induced Crystallization of Amorphous Silicon

Antimony induced crystallization of PVD (physics vapor deposition) amorphous silicon can be observed on sapphire substrates. Very large crystalline regions up to several tens of micrometers can be formed. The Si diffraction patterns of the area of crystallization can be observed with TEM (transmission electron microscopy). Only a few and much smaller crystals of the order of 1μm were formed when the antimony layer was deposited by MBE (molecular beam epitaxy) compared with a layer formed by thermal evaporation. The use of high vacuum is essential in order to observe any Sb induced crystallization at all. In addition it is necessary to take measures to limit the evaporation of the antimony.     

A CUMULATIVE FATIGUE DAMAGE RULE UNDER THE ALTERNATIVE OF CORROSION OR CYCLIC LOADING

Fatigue damage increases with the applied loading cycles in a cumulative manner and the material deteriorates with the corrosion time. A cumulative fatigue damage rule under the alternative of corrosion or cyclic loading was proposed. The specimens of aluminum alloy LY12-CZ soaked in corrosive liquid for different times were tested under the constant amplitude cyclic loading to obtain S-N curves. The test was carried out to verify the proposed cumulative fatigue damage rule under the different combinations among corrosion time, loading level, and the cycle numbers. It was shown that the predicted residual fatigue lives showed a good agreement with the experimental results and the proposed rule was simple and can be easily adopted.