Effect of Cu on Discontinuous Precipitation of a Symmetrical AlZn Alloy

The effect of Cu additions on discontinuous precipitation of AlZn alloy were studied with optical microscopy, scanning electron microscopy and X-ray diffraction. It is found that the effect of addition of 2 at. pct Cu on cellular nucleation site is not remarkable, while the effect of aging temperature on cellular nucleation site of AlZn and AIZn-2Cu alloys is fairly obvious. The cell growth rate of discontinuous precipitation of AlZn alloy is remarkably accelerated with the addition of 2 at. pct Cu. The discontinuous precipitation microstructure of AlZn alloy is not apparently affected with the addition of 2 at. pct Cu and the cellular front is still fine microstructure of spinodal decomposition. The phase constituents consist of a fcc Al-rich phase, a hcp Zn-rich phase and a CuZn4 phase. The transformation rate of discontinuous precipitation of AlZn alloy is remarkably accelerated with the addition of 2 at. pct Cu.     

Cu-Ni-Si合金的时效与析出研究

分析了冷变形量和时效温度与时间等工艺参数对Cu Ni Si合金显微硬度和导电率的影响 ,同时研究了该合金的析出物结构。结果表明 ,冷变形可加速时效过程和提高时效效果 ,在 5 0 0℃时效 1h可使合金获得较佳综合性能。合金的显微硬度和导电率等性能主要取决于析出物的析出量和颗粒大小以及弥散程度     

Cu-Ni-Si合金时效的正交试验研究

采用正交试验对Cu-3.2Ni-0.75Si-0.3Zn合金的时效工艺进行了研究。结果发现,各因素对合金导电率和显微硬度影响程度的主次顺序分别为:时效温度>合金状态>时效后冷变形量>时效时间和时效温度>冷变形量>合金状态>时效时间。在保证合金性能不降低的情况下,该合金热轧板材经60%冷变形后,可直接进行时效而省去固溶处理。合金经最佳工艺时效和60%冷变形后,导电率和显微硬度分别可达41.96%I-ACS和263.4Hv。     

Cu-Ni-Si合金的时效析出与再结晶

通过分析时效期间Cu-Ni-Si合金显微硬度、导电率及微观组织的变化,研究了析出相和再结晶行为的相互作用,以期为该合金多级复合工艺的制定提供参考.研究发现,时效初期析出相对随后的再结晶过程具有强烈阻碍作用.在450、550℃较低温度时效时,合金发生原位再结晶,析出相在其体积分数略微升高或不变的情况下发生粗化;导电率上升趋势为先快后慢并趋于稳定,因而其变化曲线上无峰值出现;显微硬度则由于时效后期析出颗粒粗化,析出强化效果降低而出现峰值.在750℃高温时效时,合金发生不连续再结晶,析出相在体积分数略有降低的情况下发生粗化;导电率先快速上升后缓慢下降,因而出现峰值,而显微硬度由于析出物迅速粗化,一开始就表现为持续下降.     

Aging Kinetics in a CuNiSiCr Alloy

The aging precipitation behavior in solution treated Cu-Ni-Si-Cr alloy has been studied in terms of the analyses of the variations in electrical conductivity. On the basis of the linear relationship between the electrical conductivity and the volume fraction of the precipitates, the phase transformation kinetics equation was deduced from the Avrami empiricai formula. On the basis of this equation, transformation kinetics curves corresponding to 5% and 50% transformation were established.     

Effect of Cu on the Spinodal Decomposition of AlZn Alloy with Symmetrical Composition

1. IntroductionThe spinodal decomposition, as a method ofmaking ultra-fine microstructure, has recently beenadverted[1~3]. The Al-Zn binary system is the basis ofsome practically important systems among Al-based lightalloys, and a typical example with spinodal decomposi-tion. However, being different from others such as Cr-W with broad temperature range, the miscibility gapof the Al-Zn system remains stable at higher tempera-tures (277~350°C)[4]. The discontinuous precipitation ofthe β Z…     

添加微量元素对Cu-Ni-Si合金性能的影响

分析了微量元素在改善Cu-Ni-Si合金强度同时又影响导电性的机理,综述了Zn、Cr、P、Al等微量元素对Cu-Ni-Si合金硬度、导电率等的影响规律,表明利用合金化规律在Cu-Ni-Si合金中添加不同的微量元素可以得到强度和导电率匹配良好的超高强度Cu-Ni-Si舍金.     

Microstructural Evolution of 6061 Alloy during Isothermal Heat Treatment

The semi-solid billet of 6061 aluminum alloy was prepared by the near-liquidus semi-continuous casting(LSC) with rosette or near-spheroide grains.The pre-deformation processing was applied before partial remelting to further improve the microstructure and properties of the semi-solid alloy.The effects of different processing parameters,such as holding temperature and holding time,on the semisolid microstructures during partial remelting have been investigated.It was found that the optimal partial remelting parameters should be 630℃ and 10-15 min for 6061 alloy cold rolled with 60% reduction in height of pre-deformation.The coarsening rates were anasysed by Lifshitz-Slyozov-Wagner(LSW) theory.The pre-deformed 6061 alloy exhibits lower coarsening rate constants than that of the as-cast one,and also lower than other alloys processed by different method found in previous literature.It is because the coarsening rate is associated with the initial microstructure and composition of the alloy.The secondary phases in the alloy inhibit the migration of the liquid film grain boundaries.The microstructure obtained by using the combination of near-liquidus semicontinuous casting and pre-deformation treatment is better than that without pre-deformation processing,which demonstrates that the used method is promising for fabricating high quality semi-solid alloys.     

高强度合金无氧铜导电线材研究

本文介绍了高强度合金无氧铜导电线材的成分设计和强化机理，对合金线材的微观组织及质量控制进行了研究、分析，提出了一种高强度、抗疲劳、超细铜合金导电线材及其生产工艺。     

高强高导铜合金的研究状况

高强高导电铜合金是一类具有优良综合性能的功能材料和结构材料,被广泛应用于电子、机械等领域,本文阐述了高强高导铜合金的研究现状,系统介绍了此类合金的强化机理、制备方法及组织和性能特点,并且分析了稀土的作用机制及对该类铜合金性能的影响,最后展望了该类合金的发展前景。     

铜合金在舰船上的应用

概述了造船用铜合金的开发和应用,包括螺旋桨用铜合金、冷凝管用铜合金、通海系统用铜合金等。展望了铜合金在未来舰船上的应用前景。     

Effect of Small Addition of Sc on the Microstructural Evolution in Al-15Ag Alloy

1.IntroductionIt was found that minor or trace amounts(0.1at.pct)of certain elements can cause remarkable changes to mi-crostructure and properties of aged aluminium alloys,and most trace element effects arise through changes theyinduce in the nucleation and/or growth of new phasesduring solid state transformation[1].For instance,the ad-ditions of Cd,In,Sn to Al-Cu alloys may accelerate andenhance the age hardening response at elevated temper-atures,whereas reduce the response to the hardeni…     

时效早期Al-Mg-Si合金的组织和析出相的演变

用显微硬度测试、差示扫描量热法(DSC)和高分辨透射电镜(HRTEM)观察等手段研究了Al-Mg-Si合金人工时效过程中的硬化、组织变化以及早期析出相的演变。结果表明：在170℃时效的合金具有更高的峰值硬度。在时效初期晶内析出高数量密度的溶质原子团簇和GP区,合金的硬度显著提高。在170℃处理4 h后合金的硬度达到峰值,此时晶内析出相以针状β″相为主,β″相与Al基体界面三维共格应变是合金强化的主要原因。同时,晶界析出相呈断续分布状态。随着时效时间的增加β″相开始粗化,晶界析出相的连续程度降低。在过时效阶段晶内析出相的严重粗化和数量密度的降低,使合金的硬度剧烈降低。在时效的初始阶段,合金的析出序列为过饱和固溶体→球形原子团簇→针状GP区→针状β″相。     

Improvement of yield strength of LM24 alloy

In this study, Al₂O₃ particles were employed to improve the microstructure of LM24 and therefore, to increase the yield strength and tensile strength of this kind of alloy. In situ Al₂O₃ particles were obtained by direct reaction between oxygen and Al melt at 750–800 °C. Microstructure examination shows that the size of in situ formed Al₂O₃ particles was about 1–2 μm, and interestingly, with addition of in situ Al₂O₃ particles, the coarse primary Si phase was disappeared completely. More important, the yield strength and the tensile strength of Al₂O₃/LM24 are increased by 52 MPa, 16 MPa than that of LM24 alloy with 0.1% Sb addition. The value of 181 MPa and 315 MPa is for yield strength and tensile strength of Al₂O₃/LM24 respectively. Besides, the yield strength and tensile strength are 180 MPa and 314 MPa respectively for Al₂O₃/LM24 alloy after remelting and casting. This verifies that the improvement of mechanical properties of such kind of material possesses stability and reliability.     

时效对Al-Li(2091)合金应力腐蚀行为的影响

本文研究了在不同时效状态下Al-Li(2091)合金在3％NaCl+0.5％H_2O_2溶液中应力腐蚀行为;并与传统的2024(CZ)合金进行了比较。结果表明,2091合金具有较好的抗应力腐蚀能力。利用扫描电镜与透射电镜分别对应力腐蚀断口和合金显微组织进行了观察和分析;对应力腐蚀开裂的机制进行了初步探讨。     

固溶时效处理及强变形对Cu-1wt%Ag合金的组织和性能的影响

使用真空感应炉熔炼制备了Cu-1wt%Ag合金,对目标合金在760℃下进行了4h的固溶处理,而后在500℃下进行不同时间的时效热处理,并对合金的微观组织、导电率和硬度进行观察和测试。选取4h时效后的合金进行轧制和拉拔,获得线径为1.028~0.089mm的线材,对线材的微观组织、导电率、抗拉强度进行观察和测试。结果表明,随着时效时间的延长,Ag单质逐渐在边界上析出,合金的导电率表现为先升高后稳定的规律,而硬度先增大后减小并最后趋于稳定,在4h时效状态下合金的综合性能最好。此外,随着真应变的增加,Cu-1wt%Ag合金线的抗拉强度先增大后趋于稳定,而导电率则缓慢降低。当合金丝的真应变η为10.36时,其抗拉强度可以达到778.7 MPa,导电率可以达到90.98%IACS。     

含Sc超高强铝合金热压缩时的流变行为和组织演变

在Gleeble1500试验机上,对温度范围为380~470℃和应变速率范围为0.001~10s-1的一种新型含Sc的超高强铝合金的流变行为进行研究,并用金相观察和透射电镜分析考察压缩变形时的组织演变。结果显示,真应力-真应变曲线在小应变条件下(ε<0.15)表现出峰值应力及随后的动态流变特征,这种关系可以用Zener-Hollomon指数方程来描述。指数方程中的平均热变形激活能Q为157.9kJ/mol。变形试样中的亚结构由拉长后晶粒中的少量细小的等轴多边形亚晶粒和晶界上的锯齿状组织构成。动态流变主要是由动态回复(DRV)和动态再结晶(DRX)引起。     

电场时效对LY12铝合金微变形行为的影响

研究了电场时效处理中电场强度对LY12铝合金的微屈服强度和微变形行为的影响，也研究了直流电场时效和脉冲电场时效对合金微变形行为的影响。结果表明，适当的电场时效可以使合金的微屈服强度明显提高，优选出最佳的电场时效工艺参数是：E=2kV／cm，190C／10h。     

Al-10Mg型固溶合金自然时效稳定性研究

测定了ZL30 5合金自然时效 33年的力学性能变化 ,观察了晶界的析出相 ,研究了组织和性能的关系 ,从而确定了ZL30 5合金具有长期自然时效稳定性。     

Cu—Cr—Zr合金等温时效动力学研究

本文通过测试Cu—Cr—Zr合金在等温时效过程中电阻率的变化研究了铜合金的等温时效动力学。试验中,在时效温度达到设定温度时,每lOs记录一个电压值,直到试验过程结束为止。通过分析曲线可知,Cu--Cr--Zr合金的时效曲线具有两个拐点,对应着时效析出的两个过程。最后,推导出了合金的时效动力学公式：ρ=ρmin（ρmax-ρmin）exp-（ktn）。通过对动力学公式二阶导数的分析,从数学上证明了合金等温时效两个析出过程的存在性。