Sc元素对ZL205A合金组织和力学性能的影响EI北大核心CSCD

利用金相显微镜、扫描电镜、透射电镜等手段,研究Sc含量对砂型铸造ZL205A合金的组织和力学性能的影响规律。结果表明,Sc含量低于0.12%(质量分数,下同),未发现晶粒细化效果;Sc含量为0.06%,热处理态的合金晶界出现残留颗粒状W(AlCuSc)相,随Sc含量增加,W相由颗粒状转变为连续条带状;ZL205A合金热处理后弥散析出少量Al 3(Zr x,Ti 1-x)相,添加Sc后弥散相转变为Al 3(Zr x,Ti y,Sc 1-x-y)相,弥散相的数量随Sc含量的增加而增加;由于弥散相数量的增加,Sc含量为0.06%时,合金的时效响应速率和硬度峰值均略有增加,合金的屈服强度提高了4%;Sc含量为0.12%时,晶界残留相增加,Cu在α(Al)中的浓度降低,θ′相密度明显降低,合金的时效响应速率、硬度峰值以及力学性能各项指标均大幅下降;ZL205A合金中添加0.06%的Sc,即可明显地抑制θ′相的长大。     

热处理工艺对高强高导铜合金组织级性能的影响

本研究利用多道次等径角挤压工艺制备了超细晶Cu-Cr-Zr合金棒,在450 ℃人工时效4h后,获得最佳综合性能:抗拉强度610 MPa,断裂延伸率12.5%,硬度199 HV,电导率77%IACS。通过EBSD技术和TEM分析,揭示了该工艺条件下合金主要的强化机制:超细晶组织贡献了260.6 MPa,析出相强化贡献了149 MPa,加工硬化效果为163.9 MPa。相比于等径角挤压试样,析出相取代了固溶原子,强化效果显著提高;而位错密度降低,加工硬化效果显著降低。     

Effect of ageing treatment on wear properties and electrical conductivity of Cu-Cr-Zr alloy

In this study, the effect of ageing processes on the wear behaviour and electrical conductivity was investigated. Prior to solid solution heat treatment at 920°C and ageing at 470°C, 500°C and 530°C for 1 h, 2 h and 3 h, respectively, the prepared samples were homogenized at 920°C for 1 h. After the ageing processes, all samples were characterized in terms of electrical conductivity, scanning electron microscope (with energy dispersive X-ray spectrum (EDS)) and hardness (HV5). In wear tests, pin-on-disc type standard wearing unit was used. As a result, starting from 1 h aged specimens, orderly increase of electrical conductivity was defined. From EDS analyses it was observed that Cr rate increases as precipitates grow. With increase of Cr rate there was also a defined rise of electrical conductivity. From the wear tests, it was observed that the least wear loss was in Cu-Cr-Zr alloy aged at 500°C for 2 h and the most wear loss was in specimens aged at 530°C for 2 h. Furthermore, it was observed that the friction coefficient values resulting from wear rate were overlapped with hardness results and there is a decrease tendency of friction coefficient as wear distance increases.     

Microstructural and mechanical properties evolution of magnesium AZ61 alloy processed through a combination of extrusion and thermomechanical processes

In this work, the microstructures and tensile properties of a commercial magnesium alloy “AZ61” processed by a combination of hot extrusion and thermomechanical processing (TMP) were investigated. The TMP was consisting of two or three hot rolling steps with large reductions per pass, thus allowing significant grain refinement. The microstructural evolution has been studied by means of optical and scanning electron microscopes, as well as X-ray diffraction analysis. The as-cast material is extruded in the form of a cylinder with initial diameter of 250 mm to a final diameter of 110 mm (80% reduction in cross-sectional area). Then hot rolling regimes were performed at 300 °C with different percentage of strain per pass. Tensile and hardness tests were performed in the samples (as-cast, extruded, and rolled) at room temperature in order to evaluate the mechanical properties of the material. The results of experiments demonstrated that fine grain size might be achieved in magnesium alloy AZ61 by using a two-step processing route involving an initial extrusion step followed by thermomechanical processing with large reduction in thickness per pass. This two-step process, designed to achieve average grain sizes of 10–20 μm.     

热处理对Cu-0.36wt%Cr合金组织和性能的影响

利用扫描电子显微镜、能谱分析、透射电子显微镜、光学显微镜等手段研究了热处理对Cu-0.36%(质量分数)Cr合金组织和性能的影响,分析讨论了合金性能的影响因素及强化机理.结果表明,均匀化处理可以很大程度的消除微观偏析;经(990±5)℃×1h固溶、470℃×(3～4)h时效处理后可获得较好的综合性能,强度、硬度和电导率分别为494MPa、121.5HV和80.5%IACS;时效前预冷变形可以提高时效强化的效果,时效前经38%冷加工变形后进行470℃×2h时效处理,强度、硬度和电导率可分别提高到537MPa、146.7HV和85%IACS,远远优于国内外同类材料.     

Microstructure, mechanical properties and electrical conductivity of industrial Cu-0.5%Cr alloy processed by severe plastic deformation

Microstructure, mechanical properties and electrical conductivity of industrial Cu-0.5% alloy subjected to equal channel angular pressing (ECAP) by route A and cold rolling with and without aging treatment were investigated. The lamellar grains in thickness of 100 nm were obtained after eight ECAP passes. They were not further pancake shaped, but fragmentary and obtained less sharp boundaries with more dislocations in addition to cold rolling. After aging at 450 °C for 1 h, high density of dislocations and some coarse grains were observable after ECAP and the additional cold rolling, respectively. The tensile tests show that tensile strength arrived at 460 MPa and 484 MPa after four and eight passes of ECAP, respectively, the corresponding tensile strength increased to 570 MPa and 579 MPa after the additional cold rolling. However, the electrical conductivity was not more than 35% IACS. It was proved that four passes of ECAP followed by 90% cold rolling and aging at 450 °C for 1 h offered a short process for Cu-0.5%Cr alloy to balance the paradox of high strength and electrical conductivity, under which the tensile strength 554 MPa, elongation to failure 22% and electrical conductivity 84% of IACS could be obtained. The high strength was explained by precipitation strengthening and fine grain strengthening.     

Ce对铸态Mg-6Zn合金组织与导热性能的影响EI北大核心CSCD

利用光学金相显微镜(OM)、X射线衍射仪(XRD)、扫描电镜(SEM)、能谱仪(EDS)、透射电镜(TEM)等分析手段研究铸态Mg-6Zn-x Ce合金的微观组织,利用闪光法求得合金热导率随Ce含量的变化规律。结果表明:Mg-6Zn合金主要由α-Mg和Mg 7Zn 3相组成,添加稀土元素Ce后,合金中出现三元相Ce 5(Mg,Zn)41,主要分布于晶界和枝晶间,三元相的产生对Mg 7Zn 3相有抑制作用;Ce元素的添加使合金共晶组织含量增多,且随Ce含量增加共晶组织分布的连续性增强;合金热导率随Ce含量的增加逐渐降低,原因可能是随着Ce含量升高,合金中共晶组织的体积分数增加,分布更加连续,对电子散射作用增强,延长电子传导路径,增大了热阻,使合金热导率降低。     

热处理对BT14钛合金显微组织和力学性能的影响

本文研究了BT14钛合金热处理规范→显微组织→力学性能之间的关系.结果表明:热处理工艺对组织和力学性能的影响很大.其中,随着退火温度的升高,初生α相含量逐渐减小,α相颗粒逐渐粗化,向等轴状发展;随着退火温度的升高,合金的强度和硬度逐渐减小,但塑性变化是先升高后减小的趋势.热处理强化规范中低温淬火 低温时效所得的合金综合性能较优.但BT14钛合金强化效果不明显.     

Enhanced mechanical properties and electrical conductivity in ultrafine-grained Al alloy processed via ECAP-PC

The objective of this work is to study the effect of grain refinement using equal channel angular pressing with parallel channels (ECAP-PC) on microstructure, mechanical properties, and electrical conductivity of an Al–Mg–Si alloy. The coarse grained (CG) material is subjected to ECAP-PC processing at 100 °C for 1, 2, and 6 passes. Mechanical behavior of the Al–Mg–Si alloy after ECAP-PC processing and its electrical conductivity are analyzed with respect to the microstructure developed during ECAP-PC processing. The effect of artificial aging (AA) on the microstructure, mechanical properties, and electrical conductivity of the ECAP-PC processed Al–Mg–Si alloy is investigated. It is shown that the microstructure developed during ECAP-PC processing affects the kinetics of the aging process that, in turn, affects the mechanical properties and electrical conductivity of the material. It is demonstrated that both mechanical properties and electrical conductivity of the Al–Mg–Si alloy can be simultaneously enhanced via intelligent microstructural design through optimization of the thermo-mechanical processing applied to this material.     

时效对Cu-3.2Ni-0.75Si-0.30Zn合金组织和性能的影响

研究了时效温度和时效时间对Cu-3.2Ni-0.75Si-0.30Zn合金组织和性能的影响.结果表明,合金经900℃固溶,不同时间时效处理后,第二相呈弥散分布.合金经不同冷变形后时效,能获得较高的显微硬度与导电率,当时效温度达到500℃时,其显微硬度达到253.7Hv,导电率达到40%IACS.同时建立了该合金在500℃下,关于时效时间的一元导电率方程.时效前的预冷变形能够有力的促进合金在时效过程中第二相的析出,从而提高合金的显微硬度和导电率.     

热处理对电沉积Ni-Fe合金箔组织和力学性能的影响

电沉积法制备Ni-Fe合金箔具有工艺简单,能耗低,产品规格不受限制等优点,但其塑性和弹性模量较低限制了其应用发展.为了改善电沉积Ni-Fe合金箔的力学性能并扩大其应用范围,本文通过高温热处理方法改善其力学性能,采用SEM,XRD,EBSD分析手段对电沉积Ni-Fe合金箔晶粒组织和结构进行了分析,通过高温热台显微镜进行原位在线观测晶粒组织的演变过程,并对热处理后的电沉积Ni-Fe合金箔进行力学性能分析.研究表明,热处理过程中电沉积Ni-Fe合金箔经历细晶组织阶段、混晶组织阶段和粗晶组织阶段,其中,在1 000~1 050℃容易发生晶粒异常长大.细晶组织阶段,电沉积Ni-Fe合金箔能够保证较高的强度,且塑性和弹性模量明显提高,综合性能较好;混晶组织阶段,强度和塑性较低,弹性模量有一定程度提高;粗晶组织阶段,强度很低,但塑性和弹性模量有较大程度提高.     

热处理对铸造Ti15-3合金显微组织和力学性能的影响

借助光学显微分析、ＴＥＭ和ＳＥＭ分析手段研究了不同热处理工艺对Ｔｉ１５－３合金显微组织和力学性能的影响。结果表明：合金在铸态时的组织特征为粗大的β相,由于合金中没有析出相的弥散强化作用,因而合金的强度低,在不同温度时效处理后,在晶内和晶界析出α相,随着时效温度和时效时间的增加,析出相不断粗化,与铸态相比,合金时效后强度大幅度提高而处伸率大幅度下降,在变形过程中,合金中的位错在析出相周围形成缠结,合     

FeNiCo高温恒弹性合金特性研究

主要研究了FeNiCo合金成分组织及性能的关系,探讨了加工工艺对弹性性能的影响。在-60~+185℃温度范围内,合金的频率温度系数fβ稳定在(-2.0~+3.0)×10-5/℃。     

Effect of grain size distribution and texture on the cold extrusion behavior and mechanical properties of AZ31 Mg alloy

An experimental investigation into the cold extrusion and the subsequent annealing processes of an Mg-2.8%Al-0.83%Zn (AZ31) Mg alloy was studied. Microstructures, grain size distribution and texture evolution of the as-extruded and as-annealed specimens were investigated by optical microscopy and electronic backscattered diffraction (EBSD). Tensile tests along the extrusion direction were carried out at room temperature. It is found that firstly, the uniform microstructure with log-normal grain size distribution led to homogeneous cold deformation and good appearance without cracks for the as-extruded rods; secondly, texture was able to soften the yield strength induced by grain refinement and even overcame the refined grain size effect; thirdly, well-distributed microstructure reduced the absolute difference of yield strength for the sub-micrometer-grain Mg alloys.     

铸造Mg-RE合金的显微结构及其蠕变行为

研究了铸造Mg-RE合金的高温蠕变特性,通过SEM和TEM观察,讨论与分析了该合金的蠕变机制.结果表明:在473K、应力低于100MPa条件下,该合金具有良好的蠕变抗力,其稳态蠕变速率低于2.66×10~(-6)s~(-1);富含Ce、La、Nd等稀土元素的共晶β相和蠕变期间动态沉淀产生的晶界强化及沉淀强化是该合金的主要强化机制,而孪晶切变和共晶β相开裂致使其高温蠕变抗力显著降低。     

Effects of age heat treatment and thermomechanical processing on microstructure and mechanical behavior of LAZ1010 Mg alloy

An Mg–Li–Al–Zn (designated as LAZ1010) alloy containing about 10 wt% of Li has been prepared by melting and solidification in a carbon steel crucible, and extruded at a billet preheating temperature of 200 °C with an extrusion ratio of approximately 29. Effects of age heat treatments and thermomechanical processing on microstructures and mechanical properties were performed in this study. Hardness, optical microscopy, X-ray diffraction studies, and tensile testes were carried out to explore the variations in microstructures and mechanical behaviors during processing. The results showed that LAZ1010 alloy presented age hardening effect at temperatures below 50 °C. Rapid decrease in hardness with aging temperature at intermediate temperatures should be resulted from the transformation of θ phase into the equilibrium phase AlLi. Kocks–Mecking type plots were used to illustrate different stages of work hardening of the cold rolled specimens. The results indicated that cold rolled LAZ1010 alloy showed stage III and stage IV work hardening behaviors.     

变形温度与应变速率耦合作用对TWIP效应Ti-15Mo合金力学性能的影响EI北大核心CSCD

变形温度和应变速率均影响β型钛合金的力学性能,且其影响均关联塑性变形过程中变形方式的变化。利用TEM,EBSD,SEM,XRD,OM和拉伸试验机研究变形温度和应变速率耦合作用对{332}〈113〉孪生诱发塑性效应Ti-15Mo合金力学性能的影响。结果表明:在298 K和573 K下,屈服强度均随应变速率的增加逐渐升高,即依赖于位错热激活过程,且573 K下显著的位错热激活作用使得屈服强度表现出更大的应变速率依赖性。不同于298 K下,Ti-15Mo合金在573 K下通过{332}〈113〉孪生和位错滑移耦合变形;构建的流变应力模型表明位错强化成为其主要强化方式。高应变速率下,塑性变形早期形成的更多孪晶虽然会抑制孪生的进一步产生降低加工硬化率,但同时有效降低位错不均匀分布引起的局部应力集中延缓颈缩的发生;两个方面的共同作用使得Ti-15Mo合金在变形温度和应变速率耦合作用下呈现出更小的应变速率依赖性。     

Effect of heat treatment on mechanical properties of alloy 909

Abstract

Alloy 909 is a Ni–Fe–Co alloy that exhibits a low coefficient of thermal expansion and high strength at elevated temperatures. These characteristics are suitable for demanding high temperature uses such as turbine components for aerospace and energy generation. The mechanical properties are achieved by heat treatment (solution and aging) that affects the microstructural characteristics such as grain size and precipitation of intergranular and transgranular particles. This work summarises the results of trials conducted to determine the conditions that assure the desired mechanical properties in high temperature ring rolled pieces. Results of tensile, hardness and stress rupture tests are complemented by microstructural analyses. These studies allowed for establishing a robust method for the manufacture of rings; no degradation of the product, either metallurgical or due to properties, has been reported after the method was implemented.     

Thermal conductivity of Cu-4.5 Ti alloy

The thermal conductivity (TC) of peak aged Cu-4.5 wt% Ti alloy was measured at different temperatures and studied its variation with temperature. It was found that TC increased with increasing temperature. Phonon and electronic components of thermal conductivity were computed from the results. The alloy exhibits an electronic thermal conductivity of 46.45 W/m.K at room temperature. The phonon thermal conductivity decreased with increasing temperature from 17.6 at 0 K to 1.75 W/m.K at 298 K, which agrees with literature that the phonon component of thermal conductivity is insignificant at room temperature.     

中间形变热处理对2A97铝锂合金组织和性能的影响

通过室温拉伸、晶间腐蚀、电子背散射衍射(EBSD)、透射电镜(TEM)等测试方法,对中间形变热处理过程中进行不同压缩变形量处理的2 A97铝锂合金厚板短横向室温拉伸性能、晶间腐蚀性能和合金的宏微观组织进行了系统研究.结果表明,随压缩变形量的增加,合金再结晶程度提高,强度和伸长率先增加后降低.压缩变形量为20％时,再结晶晶粒细小,晶粒内包含均匀弥散分布的δ'相,晶界处的δ'相断续分布,合金的拉伸性能最好,伸长率明显提高;压缩变形量为25％时,合金的耐晶间腐蚀性能最好.合金的拉伸性能和腐蚀性能是由晶粒形貌和析出相的数量及分布共同作用的结果.