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根据稀土元素在镁合金中存在的形式及其作用,综述了稀土Ce、Nd、Y、Er及Sc在镁合金中的晶粒细化效果及其作用机理。一定量的Ce、Nd、Y、Er及Sc对镁合金晶粒均有细化作用,根据稀土固溶度的不同,其细化合金晶粒所加入的量也不同;镁合金晶粒开始粗化时所添加的稀土量是随着其在镁合金中的固溶度增加而增大的。 相似文献
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主要耐热镁合金系的研究进展 总被引:2,自引:0,他引:2
综述了Mg-RE、Mg-Al及Mg-Zn三大耐热镁合金系的强化途径、机制及其研究进展,针对耐热镁合金当前存在的问题,对今后的研究提出了一些建议. 相似文献
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通过熔炼铸造工艺制备了Cu-Cr和Cu-Cr-Mg合金,评价了Mg元素对Cu-Cr合金硬度、导电和抗软化性能的影响,研究了Mg元素对Cu-Cr合金析出相的细化作用,探讨了Mg元素的迁移行为。结果表明,相比于Cu-Cr二元合金,时效态Cu-Cr-Mg合金具有更高的硬度和软化温度,且保持较高的导电性能。两种合金的主要时效强化相均为纳米Cr析出相,Mg元素的加入抑制了纳米沉淀相的长大和结构转变,峰时效态Cu-Cr-Mg合金的析出相与基体可能仍保持共格界面关系,过时效态合金中出现与Heulser相结构相同的析出相,且峰时效态Cu-Cr-Mg合金经过高温保温处理后,其强化相的尺寸明显小于Cu-Cr合金析出相。EDS的结果表明,在时效初期Mg和Cr共存于析出相内部,而在时效后期析出相内部只有Cr元素存在,Mg元素发生迁移,同时理论估算结果显示,Mg元素可明显降低Cu(fcc)/Cr(bcc)之间的界面能,导致其偏聚于基体/析出相界面处,这可能是Mg元素能够细化析出相和提高合金性能的主要原因。 相似文献
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Wrought aluminum alloys can be effectively fabricated by a strain-induced, melt-activated (SIMA) process. The SIMA method involves plastic deformation of an alloy to some critical reduction point and a semi-solid heat treatment in the solid–liquid temperature range. The semi-solid heat treatment is a key process to control the semisolid microstructures. In this paper, the microscopic morphology of a cold-deformed SIMA treated Al–4Cu–Mg alloy has been investigated, and the effects of microstructural evolution, precipitation behavior and dislocation morphology on the mechanical properties are discussed. The experimental results show that the number of CuAl2 (θ phase) precipitates and the dislocation density of Al–4Cu–Mg alloy decreased gradually by the semi-solid heat treatment. Moreover, unique dislocation morphologies including helical dislocations and dislocation loops appeared and evolved to reduce the stored energy. With an increase of the holding time in the semi-solid heat treatment, the ultimate strength and yield strength decreased. The reduction of these mechanical properties of the SIMA treated Al–4Cu–Mg alloy is mainly due to the decrease of refinement strengthening, solution strengthening, and dislocation strengthening in the semi-solid heat treatment. 相似文献
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微量Sc和Zr对Al—Az—Mg合金组织与性能的影响 总被引:9,自引:0,他引:9
采用铸锭冶金法制备了Al-6.2Zn-2.0Mg-0.25Zr和Al-6.2Zn-2.0Mg合金,测试不同处理态的拉伸力学性能。利用金相显微镜和透射电子显微镜研究其不同处理态的显微组织,结果表明:添加微量Sc和Zr可明显细化合金的铸态晶粒,并显著提高Al-Zn-Mg合金的力学性能,其作用机理主要为Al3(Sc,Zr)造成的细晶强化,亚结构强化和弥散强化。 相似文献
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The notch tensile behavior of extruded Mg–6RY–4Zn and Mg–9RY–4Zn (RY: Y-rich misch metal) alloys containing long period stacking ordered (LPSO) phase tested from room temperature to 250 °C was investigated. LPSO long-strips crack more severely in notch samples compared with that in smooth samples. The UTS values are above 300 MPa and the notch sensitivity ratio (NSR) values are larger than 1 in both alloys because the severe crack of LPSO phase costs more energy in notch samples. Furthermore, the NSR value rises with increasing the RY content or elevating the test temperature. The strengthening effect of LPSO phase is more remarkable at high temperatures. The notch leads the fracture mode of the two alloys changing from ductile fracture to brittle fracture. Designing complex shape components should consider the NSR and plasticity of Mg–Y–Zn alloys together. 相似文献
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基于高强度耐火Al-Mg合金开发需求,设计并制备了6种Mo含量(质量分数)的Al-Mg合金,经变形热处理获得H3xx态轧板,结合光学显微镜、X射线衍射仪、拉伸试验机、带有能谱仪(EDS)的蔡司扫描电镜(SEM)等表征设备对各合金轧板微观组织和短时高温力学性能进行检测分析,揭示了微量Mo对Al-Mg合金的强韧化机理。结果表明:Mo合金化H3xx态Al-Mg合金具有较高的力学性能,这主要归功于与铝基体呈半共格关系的Al12Mo弥散相起到的弥散强化效果和抑制再结晶作用,但过量的Mo易使Al-Mg合金形成较高Mg固溶度的难熔Al12Mo结晶相,不利于合金性能提升。Al12Mo弥散相具有一定的高温稳定性,高温状态下显著阻碍再结晶晶粒长大,进而提高Al-Mg合金高温性能。Mo含量为0.08%时的高温性能最佳,高温强度最大提升22.5%。随着Mo含量的增加,Al-Mg合金常温力学性能和短时高温力学性能都有所提高。 相似文献
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Shuhua Cai Ting Lei Nianfeng Li Fangfang Feng 《Materials science & engineering. C, Materials for biological applications》2012,32(8):2570-2577
In this study, binary Mg–Zn alloys were fabricated with high-purity raw materials and by a clean melting process. The effects of Zn on the microstructure, mechanical property and corrosion behavior of the as-cast Mg–Zn alloys were studied using direct observations, tensile testing, immersion tests and electrochemical evaluations. Results indicate that the microstructure of Mg–Zn alloys typically consists of primary α-Mg matrix and MgZn intermetallic phase mainly distributed along grain boundary. The improvement in mechanical performances for Mg–Zn alloys with Zn content until 5% of weight is corresponding to fine grain strengthening, solid solution strengthening and second phase strengthening. Polarization test has shown the beneficial effect of Zn element on the formation of a protective film on the surface of alloys. Mg–5Zn alloy exhibits the best anti-corrosion property. However, further increase of Zn content until 7% of weight deteriorates the corrosion rate which is driven by galvanic couple effect. 相似文献
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Microstructure and mechanical properties of Mg–6Sn and Mg–6Zn alloys prepared by different processing techniques: a comparative study
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N. El Mahallawy A. Ahmed Diaa M. Akdesir H. Palkowski 《Materialwissenschaft und Werkstofftechnik》2016,47(1):37-46
The microstructure and mechanical properties of Mg–6Sn and Mg–6Zn are investigated and compared in cast/heat treated, rolled and extruded conditions. Compared to the heat treated alloys, the grain size of both alloys decreases while the volume fraction of precipitates increases by rolling and extrusion in Mg–6Sn alloy at 350 ºC due to dynamic recrystallization and dynamic precipitation of intermetallic phases. Zinc has a stronger grain refining effect than tin in the heat treated alloys while the opposite effect is found in the rolled and extruded alloys. For the heat treated alloys the Mg–6Sn the strength reached 158.7 MPa with elongation 5.2% while Mg–6Zn exhibited a higher strength of 183.7 MPa and 8.4% elongation. In rolled condition the strength of Mg–6Sn reached 224 MPa with 1.6% elongation while Mg–6Zn exhibited a lower strength of 124 MPa and a lower ductility of 0.5% elongation due to susceptibility to hot shortness. Extrusion of Mg–6Sn alloy resulted in the maximum attained strength of 281 MPa and an elongation of 6.1% while Mg–6Zn cracked during extrusion due to hot shortness. The results obtained are discussed with respect to microstructure evolution in both alloys. 相似文献
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M. Hockauf R. Schönherr S. Wagner L. W. Meyer H. Podlesak S. Mücklich B. Wielage L. Krüger F. Hahn D. Weber 《Materialwissenschaft und Werkstofftechnik》2009,40(7):540-550
Equal‐channel angular pressing of medium‐ to high‐strength precipitation hardening aluminium wrought alloys The study deals with the optimisation of medium‐ to high‐strength aluminium wrought alloys. The goal is to define processing routes in order to improve the mechanical properties if compared to their commercial counterparts. It is shown for the Al‐Mg‐Si and the Al‐Cu‐Mg‐Si system that the application of ECAP enables a significant increase in strength. The strengthening as well as the grain size reduction respectively, benefit from increasing alloying as well as from the degree of aging. It is also shown that the presence of a considerably fine particulate reinforcement hardens the material tremendously during ECAP. The combination of a pre‐ or post‐ECAP heat treatment enables the improvement of the workability on the one hand, reducing the loads on the die, and also gives a better ductility on the other hand. This positive effect is particularly pronounced for low alloying contents and high aging temperatures and can be attributed to the interaction of deformation induced defects and the precipitation activity. The combination of an appropriate set of ECAP parameters (heat treatment condition, ECAP‐strain, ‐temperature, ‐backpressure) enables the efficient production of outstanding properties. Due to the low workability of AA7075 (Al‐Zn‐Mg‐Cu system) no significant improvement in properties was achieved. 相似文献
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Qingwei Ding Yanlin Pan Shengli Hou Linzhong Zhuang 《Materials Science & Technology》2019,35(9):1071-1080
The addition of 3?wt-% Zn to the traditional Al–Mg alloy doubled its strength. To understand the strengthening mechanism, the enhancement in strength with the variation in Mg content was studied. The grain boundary and solid solution strengthening decrease with the reduction in the Mg content; however, their contributions to the yield strength are insignificant. The contribution of precipitation strengthening to the yield strength is more than 80%; however, due to the unchanged precipitate characteristics, the strengthening effect changes slightly with the variation in the Mg content. The reduction in strength is primarily due to Mg solid solution strengthening. The variation in the ductility of Al–Mg–Zn alloys was studied by fracture analysis. 相似文献