平衡相对8090Al－Li合金力学性能的影响

研究了一种８０９０Ａｌ－Ｌｉ合金中平衡相Ｔ２（Ａｌ６ＣｕＬｉ３）和δ（ＡｌＬｉ）数量变化对合金室温力学性能的影响。结果表明，合金经过双级时效（２１０－３００℃，４ｈ＋回复处理＋１６０℃，１００ｈ）后，Ｔ２相的大量析出会使合金的强度有所降低，塑性有一定程度升高，而δ相的大量析出迅速降低合金的强度，大幅度提高塑性。     

8090Al—Li合金的疲劳裂纹扩展

研究了8090型Al—Li合?疲劳裂纹扩展行为以及组织结构和环境的影响,结果表明,在空气中,自然时效和欠时效?现出最好的疲劳裂纹扩展阻力,其次是峰时效状态,而过时效状态的疲劳裂纹扩展阻力最低,在3.5%NaCl水溶液中,时效状态对疲劳裂纹扩展行为有着同空气中相同的影响规律,但在同样的时效条件下,在3.5%NaCl水溶液中的疲劳裂纹扩展阻力要比空气中的低,在相同的应力强度因子范围△K作用下,缺口短裂纹和物理短裂纹均表现出比长裂纹高的扩展速率,用位错的平面滑移性和循环滑移可逆性解释了时效的影响,用裂纹的闭合效应和裂纹尖端塑性区尺寸说明了长短裂纹扩展行为的差别。     

8090Al—Li合金疲劳短裂纹门槛值的研究

本文研究了8090Al-Li合金穿透疲劳短裂纹的门槛值,测定了不同长度短裂纹的门槛值和裂纹闭合效应,探讨了该合金疲劳短裂纹门槛值、裂纹尾迹和裂尖屏蔽之间的关系,给出了该合金穿透疲劳短裂纹的上界值和理论最低门槛值。     

8090Al—Li合金定向凝固界面形态与溶质偏析

本文阐述了定向凝固参数对8090Al-Li合金固液界面形态和溶质偏析行为的影响。结果表明:当下拉速度R<0.13mm/min(温度梯度G_L=130℃/cm)时,可得到平面凝固组织,当R>0.75mm/min(G_L=130℃/cm)时,可获得枝晶组织,且R越大,枝晶越细小。胞晶组织存在范围很窄,元素Cu偏析较严重,杂质元素Fe,Si也有很大偏析,界面形态对溶质偏析行为有显著影响。以粗枝晶凝固时,偏析比较大,凝固组织粗大。     

冷轧工艺对Al－Mg－Li合金力学性能的影响

本文研究了冷轧工艺对０１４２０合金力学性能的影响。结果表明．合金经过退火及包铝处理后，冷轧性能得到改善，合金具有较好的综合力学性能。文中还分析了冷轧工艺对合金强度及塑性的影响。最后得出冷轧变形率与合金力学性能达到最佳匹配的冷轧工艺     

Al—Li—Zr合金的分级时效

用透射电镜研究了Al—2.31Wt％Li—0.34Wt％Zr合金的分级时效过程。通过控制Li含量、固溶温度和时效温度,探寻β′(Al_3Zr)和强化相δ′(Al_3Li)最佳弥散分布条件。Li的添加,在673K一级时效的初期,能促进β′相的析出并抑制过时效进程;在473K二级时效后,由于δ′(Al_3Li)相与β′(Al_3Zr)相形成复合析出组织,屈服应力达到280兆帕。分级日于效是提高Al—Li—Zr合金强度和韧性的新途径。     

平衡相对8090Al—Li合金力学性能的影响

研究了一种８０９０Ａｌ－Ｌｉ合金中平衡相Ｔ２（Ａｌ６ＣｕＬｉ３）和δ（ＡｌＬｉ）数量变化对合金室温力学性能的影响。结果表明，合金经过双级时效（２１０－３００℃，４ｈ＋回复处理＋１６０℃，１００ｈ）后，Ｔ２相的大量析出会使合金的强度有所降低，塑性有一定程度升高，而δ相的大量析出迅速降低合金的强度，大幅度提高塑性。     

MECHANICAL PROPERTIES OF Al-Li ALLOY 8090 AT CRYOGENIC TEMPERATURES

Cryogenic strength,ductility and toughness of AI-Li alloy 8090 were found to be superior tothose at ambient temperature,and up to optima at about 20 K.Different aging regimes mayonly influence on its cryogenic yield strength and elongation.     

MICROSTRUCTURE AND MECHANICAL PROPERTIES OF 8090 Al-Li ALLOY

The change of mechanical properties of the 8090 Al-Li alloy influenced by aging is attributedto the change of δ′-phase particle size and the precipitation of S′-phase.The δ′-phase mayeasily precipitate and rapidly grow,but the S′-phase can only precipitate with a longer stageof incubation.The precipitation of S′-phase would be promoted by cold working prior to ag-ing.The co-precipitation of δ′- and S′-phase could improve the strength and plastieity of thealloy,for which aging at 190℃.for 20—30 h seems to be optimal.In addition,the precipitatefree zone( PFZ)can form at high angle grain boundary and its width is over 200 nm in peakaging condition.But at sub-grain boundary,the formation of PFZ is difficult.     

Al—Li合金的疲劳性能

研究了8090Al—Li合金在自然和人工时效状态下光滑样品的室温疲劳寿命,以及在100,150和200℃下的高温疲劳性能。结果表明:人工时效的8090合金的疲劳寿命高于自然时效的;在两种时效状态下,与传统的高强Al合金LC4和LY12相比较,Al—Li合金的疲劳寿命均高。人工时效的8090合金随实验温度的升高,疲劳寿命明显降低;自然时效的8090和LY12合金,高温疲劳寿命虽然略有降低,但在200和150℃时分别有所提高。断口观察表明:Al—Li合金的疲劳裂纹均在表面和亚表面的冶金缺陷处萌生;且层状断裂特征比传统的Al合金更加明显。     

8090Al-Li合金的微观结构与力学性能SCIEI

本文系统地研究了8090Al-Li合金的微观结构与力学性能的关系。结果表明,合金性能的变化主要归因干δ′颗粒尺寸的变化和S′相的析出。δ′相容易析出并迅速长大,而S′相析出的孕育期较长,时效前冷变形可促进S′相析出。δ′相和S′相共同析出可改善合金强度和塑性,其最佳时效条件为190℃,20—30h。另外,在有平衡相析出的高角晶界容易形成无沉淀区,在峰值时效条件,其宽度可达200nm以上,但在亚晶界难以形成。     

THERMAL CONDUCTIVITY OF Al-Li ALLOY AT CRYOGENIC TEMPERATURES

ＴＨＥＲＭＡＬＣＯＮＤＵＣＴＩＶＩＴＹＯＦＡｌ－ＬｉＡＬＬＯＹＡＴＣＲＹＯＧＥＮＩＣＴＥＭＰＥＲＡＴＵＲＥＳ￥ＳｕｎＤｏｎｇｓｈｅｎｇ；ＬｉＦｅｎｇｚｈａｏ；ＳｈａｎｇＬｅｉ（ＤｅｐａｒｔｍｅｎｔｏｆＭａｔｅｒｉａｌｓＳｃｉｅｎｃｅａｎｄＥｎｇｉｎｅ...     

INTERFACE MORPHOLOGIES AND SOLUTE SEGREGATION OF Al-Li ALLOY 8090 DURING UNIDIRECTIONAL SOLIDIFICATION

The solid-liquid interface morphology and solute segregation behaviour of AI-Li alloy 8090during unidirectional solidification were studied by the liquid metal quenehing method undervaried processing conditions.When solidification rate,RO.75 mm/min (temper-ature gradient,G_L=130℃/cm),the structure revealed of planar or dendritic interfacerespectively.With the increase of R,the interface morphology becomes cellular from planargradually,within a narrow range.And the greater the R,the,finer the dendrite.Segregationof element Cu and impurity elements Fe and Si are quite severe,the interface morphologymarkedly influences on solute segregation.During solidification at coarse dendrite interface,their segregation ratios are rather great and solidified structure is coarse.     

微量Y对Al—Li合金的析出相和力学性能的影响

研究了Y(0.1、0.5wt-％)对Al-Li-Cu—Mg—Zr合金析出相与拉伸性能的影响结果表明:Y可使铸态合金晶粒细化:促进β′(Al_3Zr)相析出:抑制δ′(Al_3Li)相的长大速度:使S′(Al_2CuMg)相的分布均匀化.添加0.1％Y能改善合金塑性而不降低强度:添加0.5％Y可使强度提高而塑性不降低