Cu-Ni-Si-Cr合金的时效析出与再结晶

研究了Cu-Ni-Si-Cr合金在时效过程中，析出与再结晶的交互作用及其对合金性能的影响。研究结果表明，形变使合金时效析出相更加细小、弥散，析出对再结晶的形核和长大过程产生阻碍作用。在再结晶的形成和长大过程中，析出相在晶界前沿快速粗化或重新溶解，并在再结晶区域中重新析出，导致更加弥散的析出相分布。     

不同Ce含量的1420合金的时效过程

测定了含Ｃｅ０．０６ｗｔ％及０．１５ｗｔ％的１４２０合金板材的时效硬化曲线及室温力学性能，分析了Ｃｅ对１４２０合金时效过程的影响。结果表明：Ｃｅ含量在０．１５ｗｔ％范围内的１４２０合金时效的组织与不含Ｃｅ的１４２０合金类似，主要强化相为δ＇及δ＇／β＇复合相。微量Ｃｅ在１４２０合金中可以减缓固溶处理时的再结晶过程及细化再结晶晶粒，并促进δ＇相在时效过程中的弥散析出。添加０．０６Ｗｔ％Ｃｅ时有利于提高合金塑性，而添加０．１５ｗｔ％Ｃｅ时则有利于提高合金强度。采用４６５℃固溶，２％预拉伸变形及１７０℃／６ｈ时效，可使含微量Ｃｅ的１４２０合金板材获得较好的综合力学性能。     

Zr和 Mg对快速凝固Cu-Cr合金时效析出过程的影响

快速凝固ＣｕＣｒ和ＣｕＣｒＺｒＭｇ合金经时效处理后显微硬度显著升高,在５００℃时效后,ＣｕＣｒ合金的硬度峰值为２０６ＨＶ,ＣｕＣｒＺｒＭｇ合金的硬度峰值为２５０ＨＶ。用透射电镜对两种合金时效过程中析出相的变化及其对显微硬度的影响进行了分析。ＣｕＣｒ合金达到峰值硬度时析出相为与母相共格的面心立方Ｃｒ,随后逐渐与母相失去共格关系并转变成体心立方的Ｃｒ。ＣｕＣｒＺｒＭｇ合金对应峰值状态的析出相为Ｈｅｕｓｌｅｒ相ＣｒＣｕ２（ＺｒＭｇ）,过时效状态下转变成面心立方的Ｃｕ５Ｚｒ和体心立方的Ｃｒ     

Cu-Ni-Si合金二次时效时的再结晶行为

利用透射电镜、显微硬度法和电导率法,研究了Cu-Ni-Si二次时效过程中显微组织、硬度及导电率变化情况.结果表明:二次时效可使合金在较短的时效时间内获得更高的导电率,经预时效后冷变形的合金,溶质原子可借助密集且分布均匀的位错网络由铜基体快速传输至析出物处或析出物的形核部位完成析出过程,使铜基体得到快速的净化,从而获得较高的导电性.Cu-3.2Ni-0.75Si合金经预时效 变形后的时效过程中,可发生原位再结晶和不连续再结晶两种形式的再结晶.再结晶的形式主要决定于预时效时析出相的大小和冷变形的程度,稳定细小的析出相促使原位再结晶的发生,原位再结晶使合金微观组织中析出相比较细小,因而保持较高的硬度;亚稳的析出相在再结晶过程中将向稳定相转变,相变动力与形变储存能共同作用促使合金发生不连续再结晶,使合金硬度迅速下降,析出相快速粗化.     

QBe2铜合金再结晶与时效析出交互作用机制的研究

研究了ＱＢｅ２铜合金的再结晶与时效析出交互作用机制。结果表明，时效析出使再结晶温度和激活能提高，再结晶以连续和不连续方式进行；在不连续再结晶过程中，析出相在晶界前沿快速粗化或重新溶解。析出相在迁移晶界的重新析出导致不连续析出。冷变形量及时效温度是影响交互作用的主要因素。     

QBe2铜合金再结晶与时效析出交互作用机制的研究

研究了ＱＢｅ２铜合金的再结晶与时效析出交互作用机制。结果表明，时效析出使再结晶温度和激活能提高，再结晶以连续和不连续方式进行；在不连续再结晶过程中，析出相在晶界前沿快速粗人或重新溶解。     

喷射沉积Al—2.15Li—1.28Mg—1.26Cu—0.10Zr合金的拉伸断裂行为

采用新型的喷射沉积工艺制备了Ａｌ２．１５Ｌｉ１．２８Ｍｇ１．２６Ｃｕ０．１０Ｚｒ合金，对其不同时效状态的拉伸性能及断裂行为进行了研究。实验结果表明，喷射沉积ＡｌＬｉ合金经１９０℃、２０ｈ时效后达到峰时效状态，此时材料的综合性能最优（σｂ＝５２８ＭＰａ，σ０．２＝４２０ＭＰａ，延伸率为１２％）。固溶淬火态实验合金拉伸断口为完全穿晶韧窝型。时效态合金的断裂方式为穿晶和沿晶混合型。随时效时间的延长，沿晶断裂的比例增加。实验合金沿晶断裂的原因是位错的共面滑移、晶界无析出区和晶界平衡相的析出     

冷轧Cu-Cr-Zr-Co-Si合金的时效行为

通过测量Cu-Cr-Zr-Co-Si冷轧合金在等温时效过程中导电率的动态变化,基于合金导电性能与析出相转化率间的近似线性关系,建立了不同冷变形量下合金时效析出过程的动力学Avrami方程及曲线,在此基础上分析了再结晶与时效析出的相互影响。结果表明:Cu-Cr-Zr-Co-Si合金形变时效过程中,随变形量和时效时间的增加,导电率及析出相转化率均增加,这是时效过程中再结晶与时效析出相互影响、共同作用的结果。随冷变形量增加,强化相析出进程明显加快,但时效析出没有明显阻止或延缓再结晶软化过程的发生,因此大冷变形+短时时效使合金获得更高的硬度峰值,但无法同时获得最优的导电性能。只有在时效析出提前于再结晶启动,且形成的第二相对再结晶存在明显阻碍的前提下,采用冷变形+时效工艺,时效强化型铜合金才能达到最佳效果。     

AlMnFeSi合金退火过程中的微观组织及力学性能的演变

通过2种不同的均匀化热处理及随后的冷轧,使一种3xxx系模型合金获得不同尺寸和分布的弥散析出相,并使铝基体含有不同含量的Mn。系统研究不同均匀化热处理组织和冷轧变形量对退火过程中模型合金的回复与再结晶行为的影响。根据实验结果,绘制出弥散析出相和再结晶过程的相互作用时间-温度-转变曲线（TTT）。TTT曲线显示固溶体中Mn的含量和弥散析出相的颗粒密度对软化行为有强烈的影响。在再结晶退火过程中或再结晶退火之前析出的高密度、细小、弥散析出相显著阻碍软化过程,并形成粗大的再结晶组织。在没有细小、稠密的弥散相影响下的再结晶退火,可以获得均匀、细小的等轴晶。而且,弥散析出相对再结晶过程的阻碍作用取决于再结晶过程的持续时间和弥散析出相的数量。在持续时间长的再结晶过程中,细小、稠密的弥散相对再结晶有着强烈的影响,而在其他情况下影响则有限。不管再结晶过程中是否受到弥散相析出的影响,在再结晶退火之前已经存在于组织中的细小、稠密的弥散相（平均尺寸0.1μm）也会导致再结晶退火之后形成粗大的再结晶组织。     

喷射沉积Al-3．8Li-0．8Mg-0．4Cu-0．13Zr合金的显微组织与拉伸性能

采用新型的喷射沉积快速凝固工艺制备了Ａｌ３．８Ｌｉ０．８Ｍｇ０．４Ｃｕ０．１３Ｚｒ合金，并对合金的显微组织与拉伸性能进行了实验研究。实验结果表明，沉积态合金组织为细小、均匀的等轴晶，晶粒尺寸大多在５～２０μｍ范围内。经热挤压后合金组织中的晶粒呈“砖块”状或“竹节”状形貌特征，晶界上破碎的氧化物很少。时效析出不规则形状的δ′相粒子和球壳状β′δ′复合沉淀相。δ′粒子的粗化速度较快，δ′粒子间距随时间增大的趋势不明显。喷射沉积ＡｌＬｉ合金短时间时效（１９０℃，１０ｈ）即可达到峰时效状态，此时材料的综合性能最优（σｂ＝５３４ＭＰａ，σ０．２＝４８０ＭＰａ，延伸率为１０％）。与粉末冶金ＡｌＬｉ合金相比，材料的塑性明显改善而强度相当。     

INTERACTION OF PRECIPITATION AND RECRYSTALLIZATION IN RAPIDLY SOLIDIFIED Cu-Cr-Zr-Mg ALLOY

1.IntroductionCu--Cr-Zr-Mgalloysarewidelyusedinvariousaspects,suchasinelectricresistanceweldingelectrode,motor--commutatorandintegratedcircuitleadframe,duetotheirgoodthermalandelectricalconductivitiesandrelativelyhigherstrength.However,itisdifficulttofurtherimprovetheirelectricalandmechanicalpropertiesunderconventionalsohltionheat--treatment(CSHT)sincethedegreeofprecipitationhardeninguponagingisrestrictedbythelimitedsolubilityofchromiumandzirconiumincopper[1--31.Thecompositionsandthepropert…     

Recrystallization Behavior of Re-aged Cu-Ni-Si Alloy

The interaction between precipitation and recrystallization and its effect on the properties of the re-aged Cu-Ni-Si alloy are discussed. The results indicate that the pre-aging process for Cu-Ni-Si alloy was responsible to the significant strengthening effect in re-aging process, and the re-aging strengthening effect with pre-aging at 450“C for 8h was even more remarkable, Upon aging, a phenomenon of simultaneous in situ and discontinuous recrystallization was observed in the treatment of pre-aging and deformed Cu-Ni-Si alloy. On the formation and growth of recrystallization, the precipitated phases are coarsed or dissolved in the front of grain boundaries following a re-precipitation in the recrystallization area.     

Microstructures and mechanical properties of high strength Mg-Zn-Mn alloy

The microstructures and mechanical properties of a new Mg-6%Zn-1%Mn(mass fraction) wrought magnesium alloy were studied,which could be extruded smoothly at 310-330℃with a complete dynamic recrystallization.After solution treatment one and two-step aging techniques were used.All as-aged microstructures contained two types of dispersed phases:β' phases and pureα-Mn particles.The two-step aging had a better strengthening effect than the traditional one-step aging,and the strength value achieved by the two-s...     

Recrystallization and Precipitation Behavior of Cu-Cr-Zr Alloy

Recrystallization and precipitation behaviors after cold rolling and aging are investigated for Cu-0.7Cr-0.13Zr alloy. The processed alloy was characterized using the measurement of Vickers hardness, scanning electron microscopy, and transmission electron microscopy. The resultant complex microstructures are interpreted in terms of the interactions between precipitation and recrystallization. Upon aging at 500 °C for 1 h, the 45% rolled alloy exhibits a retarded recrystallization process and therefore an efficient hardening response, which are attributed to the pinning effect of fine dispersed precipitates on the dislocation. When heavily deformed and aged at high temperature, the alloy shows an accelerated process of recrystallization, and precipitates are found to coarsen.     

Mechanism and kinetics of discontinuous precipitation of the η phase in the 36NKhTYu alloy

A new mechanism of nucleation and growth of cells of the η phase in the deformed 36NKhTYu austenitic alloy has been found. The recrystallization nuclei are formed at the η-phase particles, which were precipitated according to the continuous mechanism. Simultaneously, they are nuclei of cells of discontinuous decomposition. Unlike the known growth mechanism, the η-phase cell grows in all directions until it collides with other cells. The Peterman-Hornbogen theory of discontinuous precipitation has been modified to describe the kinetics of the complex reaction of discontinuous precipitation of the η phase and recrystallization and also the kinetics of complex reaction of discontinuous coalescence of grains and phases. The theoretical dependences of the cell size on the aging time for these reactions are proportional to t ^1/3 and t ^1/4, respectively. A comparison of the theoretical and experimental results has been performed.     

快速凝固粉末冶金Mg_(80)Cu_(10)Y_(10)合金的组织与力学性能

采用快速凝固粉末冶金技术制备热挤压Mg_(80)Cu_(10)Y_(10)合金棒材,研究了快速凝固Mg_(80)Cu_(10)Y_(10)合金薄带及热挤压后合金的相结构,并对热处理工艺对合金棒材组织结构及力学性能的影响进行了分析.研究表明,采用单辊快速凝固法在辊速为1800 r/min下制备的Mg_(80)Cu_(10)Y_(10)合金薄带为完全非晶态;在热挤压过程中Mg_(80)Cu_(10)Y_(10)合金中有Mg_2Cu和Mg晶体相析出,其显微硬度比薄带有所提高,这与合金中细小Mg_2Cu颗粒的弥散析出有关;在450 ℃保温4 h后的热挤压Mg_(80)Cu_(10)Y_(10)合金中没有新相析出;随着热处理温度的升高或保温时间的延长,由于Mg_2Cu颗粒出现重溶及聚集长大现象,使得热挤压Mg_(80)Cu_(10)Y_(10)合金的显微硬度表现出逐渐下降的变化趋势.     

MICROSTRUCTURE AND DECOMPOSITION OF RS Al-Fe-Cr-Zr ALLOY

ＭＩＣＲＯＳＴＲＵＣＴＵＲＥＡＮＤＤＥＣＯＭＰＯＳＩＴＩＯＮＯＦＲＳＡｌ－Ｆｅ－Ｃｒ－ＺｒＡＬＬＯＹ￥ＸｉａｏＹｕｄｅ；ＬｉＳｈｏｎｇｒｕｉ；ＸｉｅＹｏｎｇａｎ；ＸｕＹｉｈｅｎｇ（ＤｅｐａｒｔｍｅｎｔｏｆＭａｔｅｒｉａｌｓＳｃｉｅｎｃｅａｎｄＥｎｇｉ...