铸造A18Si0.4Mg合金时效行为研究

利用硬度测定、差热扫描量热分析（DSC)、电子探针微区成分分析和透射电子显微分析(TEM)技术研究了铸造A18Si0．4Mg合金的铸态时效及固溶淬火时效(T6)行为。硬度测定结果表明：A18Si0．4Mg合金具有明显的铸态时效硬化效果，其铸态时效峰值硬度仅比T6状态硬度值低6HV。冷却速度对合金时效没有明显的影响。DSC和TEM分析结果表明：两种时效状态下合金的时效硬化均是过渡相β″和β′相析出对基体的强化。对合金在两种时效状态下析出相的分布及硬度均匀化系数进行了分析讨论。     

AlMgSi(Cu)合金中纳米析出相的结构演变

AlMgSi(Cu)合金是应用最广泛的可热处理强化铝合金,该类合金的主要性能与时效阶段析出的硬化相紧密相关。综述AlMgSi(Cu)合金在不同热处理阶段形成的纳米析出相的形貌、结构和稳定性。提出了动态结构的概念和模型,并以此揭示了纳米析出相结构演变规律及其与力学性能间的关系。在含铜6×××系铝合金的纳米析出相结构演变研究领域有若干未解决的基本问题,而这些问题的解决对高中强度6×××系铝合金的开发具有重要的指导意义。     

Al-Cu-Mn高强铝合金的时效析出相

利用金相显微镜、透射电镜(TEM)、扫描电镜(SEM)、电子衍射分析技术和能谱(EDS)等方法,对Al-Cu-Mn高强铝合金微观结构进行了观察分析。结果发现,合金沉淀相以θ′相为主并有弥散分布的θ相;晶内细小的弥散小质点为TAl12Mn2Cu相,起到弥散强化作用;还存在尺寸在2nm左右的球状颗粒Cd相,它的存在促进了强化相的形核和生长。组织主要由晶粒尺寸为30~80μm的等轴晶构成。分析还发现,合金组织存在成分相偏析,稀土等合金化元素主要偏聚在晶界上。合金有一定宽度的晶界无沉淀析出带(PFZ),晶界上有细小的沉淀物析出,是μm级的针状N相,使其伸长率降低,因此应尽量减少这些脆性相的数量。     

微量Cu对AlSiMg合金铸态时效析出行为的影响

采用DSC分析和硬度测定，研究了金属型铸造条件下微量Cu对A1Si11Mg0．3合金铸态时效析出行为的影响。实验结果表明：微量Cu对合金的铸态硬度值影响不大，但能明显提高A1Si11Mg0.3合金的铸态时效硬化潜力。DSC分析结果表明：Cu／Mg含量比小于1时，沉淀相析出孕育速度加快，Cu／Mg含量比大于1时，沉淀相析出孕育速度减慢；Cu含量对沉淀相达到最大析出速度所需时效时间影响不大；随着Cu含量的增加，反映沉淀相析出热效应的放热峰峰高增大。Cu含量对沉淀相析出行为的影响与沉淀相的组成有关，并对此进行了讨论。     

铸造Al8Si0.4Mg合金时效行为研究

利用硬度测定、差热扫描量热分析 (DSC)、电子探针微区成分分析和透射电子显微分析 (TEM)技术研究了铸造Al8Si0 .4Mg合金的铸态时效及固溶淬火时效 (T6)行为。硬度测定结果表明 :Al8Si0 .4Mg合金具有明显的铸态时效硬化效果 ,其铸态时效峰值硬度仅比T6状态硬度值低 6HV。冷却速度对合金时效没有明显的影响。DSC和TEM分析结果表明 :两种时效状态下合金的时效硬化均是过渡相 β″和 β′相析出对基体的强化。对合金在两种时效状态下析出相的分布及硬度均匀化系数进行了分析讨论     

NiTi合金中一个新的时效析出相

用自蔓延燃烧合成法(SHS)制备了比较致密的NiTi合金,并对经固溶和时效处理后的合金进行了X射线衍射和透射电子显微术分析,在样品中除了有热处理前就存在的Ti_2Ni外,又出现了两种相,一种是已报道过的Ti_(11)Ni_(14)(又称Ti_3Ni_4),为菱形结构(a=0.67nm,α=113.85°),它与基体(B2结构,a=0.302nm)的关系为:(111)_(Ti)_(11)Ni_(14)∥(111)_B_2,{110}_(Ti)_(11)_(Ni)_(14)∥{123}_(B2)另一种为新的时效析出相,可用基体中部分Ti原子被Ni原子占据形成的长程有序结构描述,晶格常数为0.873nm,分子式为Ti_(13)Ni_(14)它是一种时效析出亚稳相。     

Fe-Cu二元合金中的B2析出相及时效硬化(英文)

研究了不同成分的Fe-Cu二元合金在过饱和固溶体状态下晶粒尺寸和硬度之间的关系,分析了Cu元素的固溶强化作用。研究了Fe-Cu二元合金的时效硬化现象和Cu元素的析出过程。结果表明Fe-Cu二元合金硬度值增加近一倍。通过透射电镜观察到随时效时间的增加,析出相的尺寸逐渐增大,形状由球形变为棒状。电子衍射花样分析得知,时效处理硬度达到最大值时对应的析出相具有B2型晶体结构,与基体之间保持平行位向关系。透射电镜观察到位错与析出相之间存在典型的引力型交互作用,由于软析出相对运动位错的钉扎效应而使Fe-Cu二元合金得到有效强化。     

铸造Al-Si基合金中Mg和Cu的硬化作用分析

分析了铸造Al-Si合金中加入元素Mg和Cu对合金的固溶强化和时效硬化能力的影响.试验结果显示元素Cu对α(Al)基体具有很强的固溶强化作用,但不含Mg的合金时效硬化能力较低;元素Mg对Al基体的固溶强化作用很小,但元素Mg的加入使合金具有很强的时效硬化能力;在Al-Si合金中共同加入元素Cu和Mg使合金具有很强的固溶时效硬化能力.通过时效组织分析,对合金的时效硬化能力与时效组织的相关性进行了讨论.     

可热处理铸造Al-Si系合金时效行为研究

研究了可热处理铸造Al-Si系合金的时效行为。发现合金的时效硬化曲线表现出不同的单、双峰硬化特征。透射电镜(TEM)、高分辨电镜(HRTEM)观察和差示扫描量热仪(DSC)分析证实，时效硬化的单、双峰现象与合金的时效析出序列密切相关，AlSiMg合金的GPⅡ区和亚稳定相的形成部分重叠交叉进行，造成了时效曲线上的硬度平台；在AlSiCu合金的时效过程中，GP区向亚稳定相的直接转变，造成了时效曲线上的单硬度峰。而A354和AlSiCuMg合金中GPⅡ区向亚稳相的转变有明显的时间间隔，使合金时效硬化曲线出现了双硬度峰现象。     

Precipitation Behavior of Al-Cu-Mg Alloy During Electric Field-Assisted Aging

In this article, we report the effect of electric field (EF) on the precipitation behavior of Al-Cu-Mg alloy. It is found that the applied field increases the hardness of Al-Cu-Mg alloy at initial aging stage. The peak of the S phase formation determined by differential scanning calorimetry also shifts to lower temperature with the applied EF. These are attributed to a lower decreasing rate of density of vacancies under field which is verified by positron annihilation measurements. The built-in field caused by the rearrangement of vacancy-solute atom complexes might lower the barrier for vacancy to escape from a complex. It leads to a longer survival time of vacancies, resulting in more possible nucleation sites for clusters.     

Influence of Mg Contents on Aging Precipitation Behavior of AI-3.5Cu-xMg Alloy

The influence of Mg content on the microstructures and mechanical properties at room temperatures of Al-3.5Cu-(0.71-1.81)Mg alloys was studied.Precipitation phases in the alloys were identified by TEM and HRTEM.The results show that when Mg contents increase from 0.71 to 1.81 wt%,the precipitates are transformed from S,S″,Ω,and θ’ phases to Sand S′phases,and Ω phase is first observed in Al-3.48Cu-0.71 Mg alloy with Cu/Mg mass ratio of 5 during the conventional aging heat treatment(190 ℃/12 h).Regard to aging hardness effect of the tested alloys,the hardness of the alloys improves with the increase of Mg content,but the increases become slow when Mg content is greater than 1.35 wt%.     

Influence of Mg Contents on Aging Precipitation Behavior of Al-3.5Cu-xMg Alloy

The influence of Mg content on the microstructures and mechanical properties at room temperatures of Al-3.5Cu-(0.71-1.81)Mg alloys was studied.Precipitation phases in the alloys were identified by TEM and HRTEM.The results show that when Mg contents increase from 0.71 to 1.81 wt%,the precipitates are transformed from S,S″,Ω,and θ' phases to Sand S′phases,and Ω phase is first observed in Al-3.48Cu-0.71 Mg alloy with Cu/Mg mass ratio of 5 during the conventional aging heat treatment(190 ℃/12 h).Regard to aging hardness effect of the tested alloys,the hardness of the alloys improves with the increase of Mg content,but the increases become slow when Mg content is greater than 1.35 wt%.     

TB17钛合金在等温时效过程中的相析出行为

采用X射线衍射、扫描电子显微镜、透射电子显微镜和硬度测试分析了新型超高强韧钛合金TB17在等温时效过程中析出相的演变及时效响应。结果表明：该合金在350 ℃时主要发生β→β+ω相变,ω相为细小的颗粒。在450 ℃下进行时效处理时,α相通过ω相辅助形核的方式形核长大。在550和650 ℃时主要发生β→β+α相变,α相为片层状。在该温度范围内长时间进行时效处理的TB17合金存在2种类型α相,满足Burgers关系的1α相和不满足Burgers关系的2α相。其中2α相为孪晶α相,在1α相内部｛102｝孪晶面形核,并不断消耗1α相而长大。TB17钛合金的时效特征与其他β型钛合金相似。TB17钛合金的时效响应快,显微硬度随着时效温度升高呈现出先增加后降低的趋势,在450 ℃时效处理下硬度达到最大。     

Cu—Cr—Zr—Si合金的时效析出行为研究

通过固溶态Cu-0.37Cr-0.18Zr-0.04Si合金在450℃时效时电导率的变化规律,计算时效过程中析出相的转变比率.并确定了450℃时效时合金时效析出相转变比率与时效时间的关系以及电导率随时效时间变化的一元方程.在此基础上绘制了450℃时效时体积分数与等温时间之间关系的相变动力学"S"曲线.同时用固态热分解反应机理的微分方程探讨了合金的时效转变机制.     

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     

Precipitation Behavior of Cu-1.9Be-0.3Ni-0.15Co Alloy During Aging

In this paper,the evolutions of microstructure and mechanical properties of Cu-l.9Be-0.3Ni-0.15Co alloy were studied.The alloys in the condition of the solution treated(soft state) and 37% cold rolled(hard state) were aged at 320 ℃for different time,respectively.The mechanical properties,electrical conductivity and microstructure of the alloy aged for different time were analyzed.Additionally,the precipitation kinetics of Cu-1.9Be-0.3Ni-0.15Co alloys was investigated.X-ray diffraction and transmission electron microscopy results reveal that both continuous precipitation and discontinuous precipitation existed in the hard-state Cu-l.9Be-0.3Ni-0.15Co alloy during the whole aging process;the sequence of continuous precipitation is G.P.zone →γ″→γ′→γ.Furthermore,the precipitation transformation mechanism of softstate alloy is homogeneous nucleation,while hard-state alloy shows the heterogeneous nucleation(interface nucleation)with the nucleation rate of both states decaying rapidly to zero during aging at 320 ℃.     

Cu-Cr-Zr-Sn合金的时效析出行为与性能

采用TEM对Cu-0.22Cr-0.05Zr-0.05Sn合金不同形变热处理状态微观组织的演变以及时效过程中析出相的状态进行研究,并以此解释形变热处理过程中合金力学性能和导电性能的变化.结果表明,合金中存在2种析出相,分别是Cr相和Cu4Zr相.其中Cr相在时效过程中分别经历了固溶体、GP区、脱溶并与基体共格以及长大;而Cu4Zr相则以早期Cr析出相为核伴随析出,与基体半共格.由于析出相尺寸很小,且分布较为均匀,使合金具有很强的时效强化效果,经940℃固溶1h后冷加工至变形率为96％并在400℃时效4h,合金的抗拉强度和电导率可分别达到400 MPa和84％IACS.对于该合金,时效温度是决定合金综合性能的关键,而时效时间对综合性能的影响并不显著.     

GH 4169合金时效处理相变问题分析

对GH 4169合金进行不同工艺的时效处理,利用金相显微镜和X射线衍射仪观察和测试时效处理过程中合金的相变问题。结果表明,合金组织中各相之间的共用晶面使得不同相之间可以进行转变。常规时效处理时,γ′相转变为γ″相。长期时效处理时,γ″相转变为针状的δ相。     

Effect of Aging Treatment on Precipitation Behavior and Mechanical Properties of a Novel Aluminum–Lithium Alloy

In this work, the microstructure and precipitation phases were primarily characterized by transmission electron microscopy. The mechanical properties were evaluated by tensile and tear test. The results indicated that the samples aged at 145 °C for 45 h or 155 °C for 30 h possessed a preferable combination of strength and plasticity, owing to the precipitation of well-dispersed T1(Al2Cu Li) phases(diameter \ 150 nm). However, aging at more than 165 °C caused an obvious size growth of T1 plates, leading to the quick reduction in plasticity and toughness. Furthermore, the high Cu/Li ratio resulted in distinct precipitation features, including a shorter incubation time of T1 phase and the aggravated precipitate-free zones.