TA32钛合金板材的超塑性能研究

研究了真空环境中TA32钛合金板材在温度950℃、应变速率5. 32×10~(-4)～2. 08×10~(-2)s~(-1)条件下的超塑性变形行为。结果表明,在不同应变速率条件下,合金的流变应力曲线特征和显微组织演变显著不同。在应变速率较低(5. 32×10~(-4)～3. 33×10~(-3)s~(-1))条件下,拉伸真应力-真应变曲线呈传统超塑变形的稳态流动特征,变形后的合金中初生α相晶粒尺寸较大;在高应变速率(8. 31×10~(-3)s~(-1)～2. 08×10~(-2)s~(-1))条件下,拉伸真应力-真应变曲线中流变应力增大到峰值后快速单调递减直至试样断裂,合金变形过程中初生α相发生动态再结晶,晶粒尺寸较低应变速率条件下显著细化。950℃时,TA32钛合金板材均具有超塑性变形能力,超塑性延伸率在145%～519%之间;当应变速率为5. 32×10~(-4)s~(-1)时,具有最佳的超塑性,拉伸延伸率可达519%。断裂区形貌分析发现,TA32钛合金板材的超塑性断裂模式为空洞聚集-连接-长大型断裂。     

Effect of Rare Earth on Superplasticity of Zn—5Al Eutectic Alloy

Zｎ Ａｌａｌｌｏｙｉｓｏｎｅｏｆａｌｌｏｙｍａｔｅｒｉａｌｓｗｉｄｅ ｌｙｕｓｅｄｉｎｉｎｄｕｓｔｒｙ .Ｚｎ 5Ａｌｅｕｔｅｃｔｉｃａｌｌｏｙｉｓｎｏｔｏｎｌｙｅｘｔｅｎｓｉｖｅｌｙｕｓｅｄａｓｄｉｅ ｃａｓｔｉｎｇａｌｌｏｙ ,ｈｏｔｐｌａｔｉｎｇａｎｄｓｐｒａｙｉｎｇａｌｌｏｙ ,ｂｕｔｏｂｔａｉｎｓｒｅｃｏｇｎｉｔｉｏｎｉｎｓｕｐｅｒｐｌａｓｔｉｃｓｈａｐｉｎｇａｎｄｓｕｐｅｒ ｐｌａｓｔｉｃｔｈｅｏｒｅｔｉｃａｌｒｅｓｅａｒｃｈｅｓｏｗｉｎｇｔｏｉｔｓｅｘ ｔｒａｏｒｄｉｎａｒｙｓｕｐｅｒｐｌａ…     

搅拌摩擦处理Al3Zr/6063原位复合材料的组织和性能

研究搅拌摩擦加工工艺对Al3Zrp/6063铝基复合材料组织性能的影响。该复合材料在6063-5%(K2ZrF6)体系下原位内生获得,利用OM、XRD、SEM观测原位内生颗粒Al3Zr的形貌、分布及尺寸,分析材料性能。实验分析可得:经搅拌摩擦处理后,复合材料的增强体更加细小均匀;基体晶粒破碎,晶粒形状发生改变;材料的抗拉强度变大,延伸率变大;具有超塑性,在变形温度500℃,应变速率1.67×10-2s-1,材料的延伸率达348.16%。     

超塑Al-Mg-Li合金的显微组织与织构特性

采用一种新型形变热处理方法制备细晶Al-Mg-Li合金板材,研究静态再结晶退火对合金板材晶粒组织及超塑变形行为的影响。结果表明,晶粒尺寸、形状和织构的分布沿板材法向方向存在明显不同;表面层的晶粒组织细小、等轴,含有旋转cubeND{001}（310）取向;中心层具有粗大、长条状晶粒,含有a取向线的织构组分。随着再结晶温度的升高,整个板材的晶粒尺寸长大,中心层晶粒纵横比减小,表面层织构强化而中心层织构弱化,超塑性伸长率下降。升高再结晶温度导致整个板材内的旋转cubeND{001}（310）织构组分强化而a取向线的织构弱化。分析了不同温度下再结晶织构的形成机制。     

5A90Al-Li合金超塑性变形过程中的显微组织及微观织构演变

通过采用电子背散射衍射技术研究具有扁平状组织的5A90 Al-Li合金板材在变形条件475℃、8×10^-4S^-1时的显微组织演变。结果表明,在进行超塑性变形前,其显微组织表现为扁平状组织,具有大量的小角度晶界,且初始板材具有明显的黄铜织构{110}（112）。在变形过程中发生了晶粒的长大、晶粒形貌的改变、晶粒取向差的增大以及织构的弱化,而且大角度晶界的含量在流动应力到达最大值后开始逐渐增加。同时,对不同阶段的相关变形机制进行了讨论。超塑性变形初始阶段的主要变形机制为位错运动,随着变形的进行而开始发生动态再结晶,晶粒旋转作为晶界滑移的主要协调机制。在超塑性拉伸的最后大应变阶段,晶界滑移是主要的变形机制。     

Superplastic behavior of friction-stir welded Al–Mg–Sc–Zr alloy in ultrafine-grained condition

The present work was undertaken to improve superplastic ductility of friction-stir welded joints of ultrafine-grained (UFG) Al–Mg–Sc–Zr alloy. In order to suppress the undesirable abnormal grain growth, which typically occurs in the heavily deformed base material, the UFG material was produced at elevated temperature. It was suggested that the new processing route could reduce dislocation density in the UFG structure and thus enhance its thermal stability. It was found, however, that the new approach resulted in a relatively high fraction of low-angle boundaries which, in turn, retarded grain-boundary sliding during subsequent superplastic tests. Therefore, despite the successful inhibition of the abnormal grain growth in the base-material zone, the superplastic deformation was still preferentially concentrated in the fully-recrystallized stir zone of the material. As a result, the maximal elongation-to-failure did not exceed 700%.     

NiAl合金的超塑性行为及其变形机制

研究了等原子比NiAl合金的NiAl-25Cr,NiAl-20.4Fe-Y,Ce,NiAl-30Fe-Y合金的超塑性行为及其变形机制,结果表明,几种合金在一定条件下均表现出超塑性行为,单相NiAl超塑性变形源于变形过程中所发生的动态回夏及再结晶,两相及多相NiAl合金的超塑性变形机制则是晶粒的转动和界面的滑动。     

高强度锌铝合金研究

研究了高强度锌铝合金的熔炼工艺、机械性能和金相组织,并探讨了合金超塑性预处理工艺,进行了超塑性拉伸试验,获得最大延伸率可达900％,合金具有良好超塑性。     

THE INFLUENCE OF CAVITY DAMAGE ON MECHANICAL PROPERTIES OF SUPERPLASTICALLY-DEFORMED MATERIALS AND ITS PREDICTION

1.IhtroductionSuperplasticmaterials,whichexhibitextraoulinalllylargeelongationandlowflowstress,havebeenfoundtobeofgreatvalueinindustrialapplications,especiallyintheaerospaceindusal.Unfortunately,Inanysuchmaterialsarepronetocavitationduringsuperplashcdefonnation,whichdelightsthefoeingabilitiesanddecreasesthemechAncalpropertiesataamtemperaturepeatly,sothemechanicalpropertiesofsuperplastically--deformedpatshavereceivedconsideboleattentionduringthepastfewyears.InvestigationswerePerformedon7475alt…     

APPLICATION OF GLEEBLE 1500 ON SUPERPLASTICITY

1.~nonSuperylasticityisakindofphenomenonthatdefonnationresistanceisreducedrelnalkablyandplasticity----especiallyelongation----isremarkablyincreased.Therehasbeenoaly30years'historyforsuperplasticityresearchintheworld.Anewsubjectandanewtechnologyofsuperplasticityincludingbranchesofmaterials,mechanism,mechhocs,forminghavebeenfoundedyet.Superplasticityisbasicallyanexperimentalsubject.Itstheoryandresultsareestablishedonthebaseofexperiments.Superplasticexperimentsmainlyincludetwokinds----mechwhcala…