LY12铝合金形变热处理强化的研究

用透射电镜研究了LY12铝合金在不同形变热处理中显微组织的变化,探讨了强化的机理,找出了较佳的形变热处理工艺制度。研究结果表明:采用“固溶处理→100℃预时效6小时→冷轧25％→150℃终时效6小时”形变热处理工艺强化LY12铝合金效果较好     

超细亚晶粒铝合金的强化机理

在室温下对经过时效处理的2024铝合金实施了等效应变为0.5的等通道转角挤压(ECAP)变形,将形变强化、时效强化和晶界细化强化有机结合,制备出超细亚晶粒铝合金,其硬度、屈服强度、伸长率分别约达100 HV,130 MPa和31%.分析探讨了超细亚晶粒2024铝合金的强化机理.研究结果表明,屈服强度的实测数值和理论计算...     

7085铝合金固溶温度预热后的大应变变形强化

提出了一种工艺性能好并能将位错强化和其他强化机制有机结合的超高强7085铝合金制备技术路线,即先在固溶处理温度对7085铝合金进行预热,然后,进行铝合金冷却速度较快的大应变变形等通道转角挤压(ECAP）加工.结果表明,ECAP加工对7085铝合金产生的强化与所用模具的温度密切相关,与模具温度为400 °C的ECAP加工相比,模具温度为室温的ECAP加工对7085铝合金的强化效果显著.基于Taylor公式的定量计算结果表明,该显著的强化主要不是来自于位错强化的增加,而是来自于其他强化机制（沉淀强化、晶界/亚晶界强化等）的作用.     

铝合金强变形固溶及其时效特性的研究进展

介绍了强变形固溶现象及其研究发展过程、铝合金强变形固溶研究中有待解决的基本问题和强变形固溶铝合金的时效特性．同时,指出了铝合金强变形固溶的应用前景．     

2014铝合金的形变时效处理

采用拉伸实验、透射电镜和光学金相法,研究了固溶处理水淬后较大程度冷变形对2014铝合金时效后组织和性能的影响·结果指出:采用较大变形程度(65%)冷轧,再进行低温短时间时效(160℃,30min),可使2014合金的强度得到显著提高(σb=568MPa),其延伸率(δ=116%)仍不低于常规时效处理(固溶处理,水淬,160℃,12h)的延伸率;经这样冷变形的2014合金,在稍高温度短时间回复处理,将导致时效强化能力显著降低·     

钙的添加对铝合金热处理性能的影响

为了研究加钙的泡沫铝合金的固溶时效强化效果，研究了钙的添加对铝合金热处理后性能的影响．结果表明将钙加入到铝合金中，其铸态硬度有所降低；在铝合金中添加钙，会改变合金元素的存在形式，形成一种新的化合物相，该化合物相在加热时不溶于铝基体；随着钙的质量分数的增加，热处理后的硬度也逐渐降低，当钙的质量分数达到1．2％时，热处理前后的硬度无明显变化．     

强化固溶对7055铝合金力学性能和断裂行为的影响

残余可溶结晶相颗粒是制约高强度铝合金力学性能的重要因素．作者通过改变固溶热处理条件并结合金相组织观察和断口分析研究了强化固溶对提高7055铝合金力学性能的作用．结果表明采取逐步升温固溶处理可使最终固溶温度超过多相共晶温度而不产生过烧组织,提高残余可溶结晶相的固溶程度和合金力学性能．强化固溶的7055合金的屈服强度和抗拉强度分别达715MPa和750MPa,且延伸率约为10％;微量元素Zr比Cr更有利于提高7055合金的力学性能,且在强化固溶条件下,提高效果更加明显．通过断口分析显示,合金的断裂属晶内韧窝断裂与沿晶断裂的混合断裂;强化固溶后,残余结晶相引起的晶内韧窝断裂减少,沿晶断裂增加     

高强铝合金快速固溶工艺研究

固溶工艺是制约高强铝合金力学性能和热处理生产率的主要因素．本文以7075铝合金为例通过高温预热装炉、分级固溶等方法研究了高强度铝合金的快速固溶工艺．并结合金相组织观察和力学性能测试，分析了快速固溶对高强铝合金组织和力学性能的影响．结果表明：①固溶时间相同时，分级固溶的强度高于单级固溶的强度，分级固溶的塑性略低于单级固溶的塑性．②分级固溶时，随着二级固溶时间的增加，材料的强度增加，塑性略有降低．③采用500℃高温预热装炉、470℃／5min＋485℃／9min固溶和140℃／6h＋150℃（2／1h时效明显缩短热处理时间，提高生产率，同时力学性能仍然达到了常规热处理的水平．     

热处理工艺对6061铝合金显微组织及力学性能的影响

选取固溶温度为420、450、490、530、570℃,保温6 h,时效温度为173℃,时效时间为1、2、3、4、56、h,对6061铝合金进行固溶时效处理.采用MEF-3金相显微镜进行组织观察、EMPA-1600电子探针进行成分分析、布洛维硬度测试仪进行硬度检测,分析固溶时效对其显微组织和力学性能的影响.结果表明:固溶温度和时效时间对6061铝合金的显微组织、力学性能有一定的影响,固溶时效后可以获得大量均匀的Mg2Si强化相,且在固溶温度为530℃,保温6 h,时效温度为173℃,保温3 h时获得较高的综合力学性能.     

时效工艺对Cu-Ag-Zr合金电磨损性能的影响

对Cu-0．1Ag-0．18Zr合金时效后的电导率、显微硬度以及电滑动磨损性能进行了研究。结果表明：该合金940℃固溶1h后，在560℃时效可获得较高的电导率，在480℃时效可获得较高的显微硬度。时效前冷变形能大大加快第二相的析出过程，使合金综合性能显著提高。该合金经940℃固溶再经60％变形后，在480℃时效1h，其电导率和显微硬度分别可达85．6％IACS和HV131．2，而固溶后直接时效为81．3％IACS和HV116．1。在载流条件下，合金的磨损量随加载电流的增加而增大；磨损机制是以电蚀为主的电蚀、犁削和磨粒磨损。     

Influence of ECAP on the fatigue behavior of age-hardenable 2xxx aluminum alloy

The fatigue behavior under load control and the mechanical properties of commercial 2011 aluminum as an age-hardenable Al alloy was studied. To estimate the effects of the equal channel angular pressing (ECAP) process, solution heat treatments, and aging on the fatigue life, tests were conducted at four different stages:furnace cooling; furnace cooling plus one ECAP pass; solid solution heat treatment, quenching, one ECAP pass plus aging at peak age level; and the T6 condition. Only one pass was possible at room temperature because of the high strength of the material. The fracture surface morphology and microstructure after fatigue were evaluated by scanning electron microscopy (SEM). The experimental results revealed that the optimum fatigue life under load control, the tensile strength, and the Vickers hardness of the material were interdependent. The optimum fatigue life under load control was achieved by increasing the tensile strength and hardness of the material.     

Microstructure and properties of in-situ synthesized Cu-1 wt%TiC alloy followed by ECAP and post-annealing

A dispersion-strengthened copper alloy with 1 wt% TiC for commercial electrical-contact wires was prepared by in-situ reaction casting, grain-ultrafining by equal-channel angular pressing (ECAP) and subsequent annealing with aim to obtain excellent comprehensive performance. The results showed that fine TiC particles were in-situ synthesized in the as-cast Cu matrix and aggregated in clusters, and thus mechanical properties of the as-cast alloy deemed insufficient. Continued ECAP at 473 K significantly refined the grains of the as-cast alloy and improved the distribution of TiC particles. Due to multiple strengthening mechanisms, the ECAP-processed alloys maintained good conductivity with obviously enhanced tensile strength and hardness values. After post-ECAP annealing, the elongation and conductivity of the fine-grained copper alloy increased with the adequate tensile strength. The novel combined process endows the alloy appropriate performance to serve current high-frequency electrification railway systems.     

固溶制度对Al-5.6Cu-1.7Mg-0.2Zr-0.1Sr-0.6Ti合金挤压材组织性能的影响

通过金相组织分析、扫描电子显微镜分析、X射线衍射、硬度、电导率、室温拉伸性能、断后伸长率和抗晶间腐蚀等微观组织观察及性能表征,研究了四种不同固溶制度对Al-5.6Cu-1.7Mg-0.2Zr-0.1Sr-0.6Ti合金微观组织和性能的影响。结果表明：随着固溶温度的升高,合金中的晶粒逐渐变大;当固溶温度低于520℃时,合金中的未溶相的数量和尺寸随着固溶温度的升高而减小;当固溶制度为510℃×2 h+520℃×2 h时,合金中的未溶相开始增多,合金出现轻微过烧,断后伸长率及抗晶间腐蚀性能变差,但抗拉强度最高,达到了490.14 MPa。合金的位错强度和位错贡献值随着固溶温度的升高而减小,合金中的强化效果主要来源于固溶强化和时效析出强化。合金在T6状态下,(490℃×2 h+500℃×2 h)和(500℃×2 h+510℃×2 h)两种不同固溶制度下的抗拉强度和断后伸长率等力学性能和抗晶间腐蚀性能都较优,这两种固溶制度均是适合Al-5.6Cu-1.7Mg-0.2Zr-0.1Sr-0.6Ti合金的固溶制度。     

Microstructure evolution of Ti–6Al–4V under cold rolling + low temperature nitriding process

A new nitriding process modifying both the surface and the matrix is proposed to improve the poor wear resistance and low hardness of the titanium alloy surface. The treatment of solid solution treatment, cold rolling and low temperature nitriding was used for surface modification. The results showed that the microstructure of the Ti–6Al–4V(TC4) titanium alloy sample changed from the original α+β phase to the residual α phase, metastable β phase and martensite α′ phase after solution treatment. The results of cold rolling experiments indicated that with the increase of rolling amount, many defects generated, and the grains were first elongated and then partially broken. During the process of low-temperature nitriding the recrystallization occurred, which effectively avoided the problem of coarse matrix structure. It has been found that after low-temperature nitriding, thin strip-like α-phase with dispersed distribution, which is a typical aging structure, formed. The XRD test results indicate that steady state nitrides Ti₂N formed on the surface of the sample, but the content of Ti₂N was relatively low. Based on the morphology of content of the surface and cross-section it is believed that a special type of nitriding layerformed after low-temperature nitriding. The mechanical performance test results indicate that the wear resistance and hardness of the alloy increased significantly.     

一种活塞环用钴基高温合金的冷加工研究

研究了冷加工变形对一种活塞环用钴基高温合金硬度、抗拉强度、延伸率及微观组织的影响。结果表明：固溶状态的钴基高温合金拉伸曲线为典型的金属拉伸曲线,而冷变形状态的合金无明显的屈服阶段;随着冷形变量的增加,合金的强度、硬度逐渐增加,而塑性明显降低;合金组织中出现了大量的层错和孪晶,其硬化机理为孪晶强化。     

Microstructural characteristics and mechanical properties of Al-2024 alloy processed via a rheocasting route

This article reports the effects of stirring speed and T6 heat treatment on the microstructure and mechanical properties of Al-2024 alloy synthesized by a rheocasting process. There was a decrease in grain size of α-Al particles corresponding to an increase in stirring speed. By increasing the stirring speed, however, the globularity of matrix particles first increased and then declined. It was also found that the hardness, compressive strength, and compressive strain increased with the increase of stirring speed. Microstructural studies revealed the presence of nonsoluble Al₁₅(CuFeMn)₃Si₂ phase in the vicinity of CuAl₂ in the rheocast samples. The required time for the solution treatment stage was also influenced by stirring speed; the solution treatment time decreased with the increase in stirring speed. Furthermore, the rheocast samples required a longer homogenization period compared to conventionally wrought alloys. Improvements in hardness and compressive properties were observed after T6 heat treatment.     

Deformation mechanism of compression of 2024 Al alloy in semi-solid state

The deformation mechanism of alloy in the semi-solid state has been investigated, with the compression of 2024 Al alloy in the semi-solid state as an example. Experimental results showed that the compressive deformation of 2024 Al alloy in the semi-solid state was mainly caused by the liquid flowing under the hydrostatic compressive stress, the grain boundary sliding under the shear stress and the plastic deformation of grain under the normal compressive stress. Among them, the grain boundary sliding was mainly accommodated by the nucleation and growth of cavity under the hydrostatic tensile stress.     

焊后热处理对6082-T6铝合金焊接接头组织和性能的影响

对6082-T6铝合金焊接接头进行固溶+时效和时效两种热处理，研究不同热处理制度对其组织和性能的影响。实验结果表明：未处理的6082-T6焊接接头抗拉强度为225 MPa，断裂位置位于热影响区，接头硬度最低值均在热影响区；经时效处理后的6082-T6焊接接头处强化相分布更加均匀，焊缝区组织无明显变化，熔合区和热影响区组织轻微细化，抗拉强度为264 MPa，断裂位置仍在热影响区，接头硬度最低值均在热影响区；经固溶+时效处理后的6082-T6焊接接头处重新析出细小的强化相，熔合区和热影响区组织有明显的细化，抗拉强度提高到302 MPa，断裂发生在焊缝区，硬度值明显高于未处理6082-T6焊接接头的，硬度最低值位于焊缝区。