EFFECT OF INTERFACIAL THERMAL MISMATCH ON INTERFACIAL STRENGTH OF COMPOSITES

ＥＦＦＥＣＴＯＦＩＮＴＥＲＦＡＣＩＡＬＴＨＥＲＭＡＬＭＩＳＭＡＴＣＨＯＮＩＮＴＥＲＦＡＣＩＡＬＳＴＲＥＮＧＴＨＯＦＣＯＭＰＯＳＩＴＥＳ①ＬｉｕＲｕｏｙｕＢｅｉｊｉｎｇＩｎｓｔｉｔｕｔｅｏｆＡｅｒｏｎａｕｔｉｃａｌＭａｔｅｒｉａｌｓ，Ｂｅｉｊｎｇ１００...     

MECHANICAL PROPERTIES AND INTERFACIAL STRUCTURES OF ALUMINIUM BORATE WHISKER REINFORCED ALUMINIUM COMPOSITES

Quality 9Al_2O_3-2B_2O_3 whisker reinforced 6061Al or Al composites have beenprepared by technique of squeeze casting.The mechanical properties of the9Al_2O_3·2B_2O_3(w)/6061Al composites could be hardly improved by T6 treatment,owingto cause the remarkable interracial reaction.An observation under high resolution trans-mission electron microscope on interfaces shows that the serious chemical reaction occursand the product is Al_2MgO_4.But no such reaction is found at the interfaces of 9Al_2O_3.2B_2O_3(w)/Al composite.EDS analysis on the interfaces shows that above mentionedinterracial reaction may be resulted from the interracial segregation of Mg atoms in6061Al matrix during sequeeze casting.     

DISTRIBUTION OF Ce AND S IN Fe-C-Si ALLOY AND THEIR INFLUENCE ON MORPHOLOGY OF GRAPHITE

Electrolytic extraction-radiometry and microradioautography techniques were used to studythe distribution of nodulizing element Ce and anti-nodulizing element S in phases of highpurity Fe-C-Si alloy.The results show that,besides forming inclusions,most of Ce atomsconcentrate in graphite firstly.As the Ce content increases,the concentration of Ce ingraphite tends to saturate,relatively large amount of Ce dissolves in the alloy.Usually,thesulphur also concentrates in graphite.However,it may exist in the form of FeS at theeutectic colony boundaries,if the concentration of S is at a quite high level.Very littleamount of S dissolves in the alloy.The morphology of graphite depends upon the degree ofsaturation of Ce.It appears as nodular when Ce was saturated and,as vermicular while itwas semi-saturated.     

FINE STRUCTURES OF BOTH INTERFACES AND INTERFACIAL REACTION PRODUCTS

The characteristic of interface depending on the atomic structure exerts an inportant,andsometime controlling,influence on performance of the interacial materials.The present paper reviews the main studies on fine structure of both the materials inter-faces and interfacial reaction products in semiconductor uperlattice,metal multilayer ceram-ics and composite materials by mean of selected area electron doffraction patterns and highresolution electron microscopy.The following features of interfaces are reviewed:the orientation relationships;the char-acteristic of steps,facets and ronghness of interfaces;atomic bonding across the interface;thedegree of coherency,the structure of misfit dislocations and elastic relaxations at the inter-faces:the presence of defects at the onterfaces:the structure of the interfacial reaction prod-ucts as well as the reaction kinetics and reaetion mechanism.     

CHARACTERISTIC OF SURFACE STRENGTHENED LAYER AND FATIGUE STRENGTH OF α-BRASS

α黄铜经表面喷丸强化后,平板弯曲疲劳强度可从90 MPa提高到130 MPa。在疲劳强度应力或高于疲劳强度应力(150MPa)的作用下,表层残余压应力不发生衰减。用透射电镜逐层观察分析强化层内的组织结构,可看到喷丸强化层内出现显微变形孪晶和面缺陷,孪晶的密度随层深加大而下降。喷丸强化后,α黄铜疲劳强度的增高和残余应力不发生松弛都与强化层内的组织结构有关。     

SYNTHESIS AND MECHANICAL PROPERTIES OF NiAlBASED COMPOSITES

１　ＩＮＴＲＯＤＵＣＴＩＯＮＮｉＡｌｈａｓｒｅｃｅｉｖｅｄｍｕｃｈａｔｔｅｎｔｉｏｎａｓｐｏｔｅｎｔｉａｌｓｔｒｕｃｔｕｒａｌｍａｔｅｒｉａｌｓｆｏｒｈｉｇｈｔｅｍｐｅｒａｔｕｒｅａｐｐｌｉｃａｔｉｏｎｓ．Ｈｏｗｅｖｅｒ,ｐｏｏｒｄｕｃｔｉｌｉｔｙａｔｒｏｏｍｔｅｍｐｅｒａｔｕｒｅａｎｄｌｏｗｓｔｒｅｎｇｔｈａｔｈｉｇｈｔｅｍｐｅｒａｔｕｒｅｈｉｎｄｅｒｉｔｓａｐｐｌｉｃａｔｉｏｎ［１－６］．Ｍａｎｙｍｅｔｈｏｄｓｈａｖｅｂｅｅｎａｐｐｌｉｅｄｔｏｉｍｐｒｏｖｅｉｔｓｄｕｃｔｉｌｉｔｙ,ｓ…     

STABILITY OF WHISKERS AND INTERFACIAL MICROSTRUCTURE IN ALUMINUM MATRIX COMPOSITES REINFORCED BY K_2O·8TiO_2 WHISKERS

ＳＴＡＢＩＬＩＴＹＯＦＷＨＩＳＫＥＲＳＡＮＤＩＮＴＥＲＦＡＣＩＡＬＭＩＣＲＯＳＴＲＵＣＴＵＲＥＩＮＡＬＵＭＩＮＵＭＭＡＴＲＩＸＣＯＭＰＯＳＩＴＥＳＲＥＩＮＦＯＲＣＥＤＢＹＫ_２Ｏ·８ＴｉＯ_２ＷＨＩＳＫＥＲＳ￥ＬＩＪｉｈｏｎｇ;ＮＩＮＧＸｉａｏｇｕａｎ...     

STRENGTH AND DUCTILITY OF Ni-Cu-BASE ALLOY MONEL K-500

ＳＴＲＥＮＧＴＨＡＮＤＤＵＣＴＩＬＩＴＹＯＦＮｉ－Ｃｕ－ＢＡＳＥＡＬＬＯＹＭＯＮＥＬＫ－５００Ｗａｎｇ；ＺｈｉｘｉｎｇＸｉｅ；ＳｈｉｓｈｕＬｉｕ；ＳｈｉｇｕｉＹｕａｎ；ＣｈａｏＹａｎｇ；Ｈｏｎｇｃａｉ（ＤｅｐａｒｔｍｅｎｔｏｆＭａｔｅｒｉａｌｓＳｃｉ...     

EFFECT OF CARBON CONTENT ON MICROSTRUCTURE AND PROPERTIES OF HIGH STRENGTH AND HIGH ELONGATION STEELS

The micro structure and mechanical properties of new kind of hot-rolled high strength and high elongation steels with retained austenite were studied by discussing the influence of different carbon content. The research results indicate that carbon content has a significant effect on retaining austenite and consequently resulting in high elongation. Besides, new findings about relationship between carbon content and retained austenite as well as properties were discussed in the paper.     

THE INFLUENCE OF ENVIRONMENT ON FATIGUE AND FRACTURE OF IRON ALUMINIDES

ＴＨＥＩＮＦＬＵＥＮＣＥＯＦＥＮＶＩＲＯＮＭＥＮＴＯＮＦＡＴＩＧＵＥＡＮＤＦＲＡＣＴＵＲＥＯＦＩＲＯＮＡＬＵＭＩＮＩＤＥＳＳＴＯＬＯＦＦ，Ｎ．Ｓ．ａｎｄＡＬＶＥＮ，Ｄ．Ａ．（ＤｅｐａｒｔｍｅｎｔｏｆＭａｔｅｒｉａｌｓＥｎｇｉｎｅｅｒｉｎｇＲｅｎｓｓｅ...     

MECHANICAL ANALYSIS AND NUMERICAL CALCULATION OF BONDING STRENGTH MEASUREMENT BY INTERFACIAL INDENTATION METHOD

ＭＥＣＨＡＮＩＣＡＬＡＮＡＬＹＳＩＳＡＮＤＮＵＭＥＲＩＣＡＬＣＡＬＣＵＬＡＴＩＯＮＯＦＢＯＮＤＩＮＧＳＴＲＥＮＧＴＨＭＥＡＳＵＲＥＭＥＮＴＢＹＩＮＴＥＲＦＡＣＩＡＬＩＮＤＥＮＴＡＴＩＯＮＭＥＴＨＯＤ①ＹｉＭａｏｚｈｏｎｇ１,ＨｕａｎｇＢａｉｙｕｎ１,...     

循环变形提高SiC纤维增强铝基复合材料强度及塑性Ⅱ.理论分析

采用断裂力学方法获得了纤维增强复合材料强度与脱粘长度、纤维临界长度以及纤维体积分数的定量关系。该公式较好地预测了纤维的临界长度以及强度与纤维体积分数的关系，并再现了复合材料混合定则。该公式也较好地解释了丝状复合材料强度随短期循环变形载荷与周次增加而增加的现象。其原因是在循环变形中，纤维与基体界面结合强度发生变化，导致纤维临界长度与脱粘长度发生变化。从而使复合材料强度增加，但这种增加是有限的和有范围的。循环变形的发展最终导致强度下降。     

循环变形提高SiC纤维增强铝基复合材料强度及塑性 I.实验现象

对ＳｉＣ纤维增强铝基复合材料经不同周次循环变形载荷后强度与塑性的测试表明．循环变形可使其强度、塑性均有所提高．经循环变形载荷作用１０周次、抗拉强度提高２０％；作用１００周次．强度提高３０％．塑性也有类似的变化．这一现象与传统疲劳损伤理论不一致．通过对基体材料、ＳｉＣ纤维体以及复合材料板的各自独立循环变形实验可知、这一现象同循环变形过程中纤维与基体的界面结合强度适度降低有关，这种降低有助于复合材料的强度与塑性的配合．     

MICROSTRUCTURES AND PROPERTIES OF SiC_w/AL COMPOSITES

This paper presents an investigation on the microstructures and properties of the17v.-% SiCw/Al-12Si composites.TEM observations and EDAX analysis revealed that Aldiffuses into the SiC whiskers and that dislocations exist at the whisker/matrix interfaces.Tensile test results showed that the isothermal exposure and thermal cycle at both 573K and733 K caused the UTS reduction of the composites,and the reduction in UTS due to thermalexposure at 733 K was much more significant than that due to thermal cycle at the same tem-perature.The SiC_W/Al-12Si composites were also found to have exellent wear resistance,which does not seem to vary much with the volume content of whiskers in the ronge of 11—17%.     

SiC_w/Al复合材料的微观结构与性能

本文研究了17V.-％SiC_W/ZL109Al复合材料的微观结构和性能。透射电镜观察和能谱分析发现,在复合材料中Al扩散到SiC晶须内部,并且在晶须/基体界面处有位错存在,拉伸试验结果表明,在573和733K温度下热暴露和热循环都导致复合材料强度降低,在733K加热时间相同的条件下热暴露引起复合材料强度的降低比热循环引起强度的降低强烈。此外,SiC_W/Al复合材料还具有高的耐磨性,在所研究的晶须含量范围内(V_f=11-17％),晶须含量对复合材料的耐磨性几乎没有影响。     

THE EFFECT OF SiC PARTICLE AND WHISKER ON THE STRENGTH OF ALUMINUM ALLOY MATRIX COMPOSITES

1.IntrodurtionDiscontinuousfiberreinforcedMMCscanbemanufacturedandformedbyc0nventionalmetallurgicalmethodl1],s0theywillbefirstlyusedinindustryonamassproductionscalebecause0ftheirhighqualityandlowc0st.Sincetherearemanytypesofparticleswhichcouldbeusedt0reinforcedifferelitlightmetalalfoys,manyexperimentsneedt0bedone.Severalresearchersdevelopedsomethe0reticaJpredictionmethodstodescribethestrengthofwhiskerorparticlereinf0rcedMMCs-Theshearlagm.del[2]wasdevelopedtopredicttheStrengthofcomposit6s,b…     

喷射沉积Al-5.5Cu/TiAl3自生复合材料的微观组织及界面结构

采用喷射沉积工艺制备了Ａｌ－５．５Ｃｕ／ＴｉＡｌ３自生复合材料,并对该材料的微观组织及界面结构进行了研究。观察表明ＴｉＡｌ３与α－Ａｌ基体之间存在（０２０）Ａｌ／／（００２）ＴｉＡｌ３,［００１］Ａｌ／／［＾１１０］ＴｉＡｌ３的位向关系,力学性能测试结果表明喷射沉积Ａｌ－５．５Ｃｕ／ＴｉＡｌ３自生复合材料的抗拉强度较铸态的抗拉强度提高约１２％,延伸率提高４５０％,耐磨性则提高１５０％。     

SiCf增强Ti-48Al-1.5Mn复合材料的界面反应

利用透射电子显微镜（TEM）对SiC纤维（SiCf)增强Ti-48Al-1.5Mn复合材料的界面区域进行了分析。结果表明，在材料的复合过程中，SiCf与γ－TiAl基体之间发生了化学反应，形成了TiC1-x,Ti5Si3和Ti2AlC等一系列产物，并对这些产物的形成机制进行了分析。在高温条件下，C，Si原子从纤维向基体扩散和Ti,Al,Mn等原子从基体向纤维扩散，发生了界面反应。