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《轻合金加工技术》2021,(5)
对AZ91镁合金进行了固溶+不同深冷处理时间+时效的复合工艺处理,采用光学显微镜、X射线衍射仪、硬度仪、万能试验机以及摩擦磨损试验机等仪器设备研究了不同深冷处理时间对AZ91镁合金显微组织、力学性能及耐磨性能的影响规律。结果表明:AZ91镁合金经410℃8 h固溶+(-196)℃12 h深冷处理+180℃8 h时效复合工艺处理后,其硬度、抗拉强度及伸长率较未深冷处理的分别提高了19.2%、25%和37.4%,其平均摩擦因数与磨损率分别为0.22和0.382 mg/(m·N),较未深冷处理的降低了50%和32.7%。深冷处理工艺有效细化了AZ91镁合金组织的晶粒尺寸,促使β-Mg_(17)Al_(12)相成颗粒状且弥散均匀分布的析出,显著提高了其力学性能和耐磨性能。但随着深冷处理时间的增加,β-Mg_(17)Al_(12)相会逐渐偏聚与粗化,导致合金的力学性能有所下降。 相似文献
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为改善消失模铸造AZ91D镁合金的显微组织和力学性能,在合金中加入稀土元素Y和Gd。结果表明:Y和Gd在消失模铸造AZ91D镁合金中生成块状的Al2Y和Al2Gd相,细化基体组织,并使β-Mg17Al12相形貌由网状转变为断续状和颗粒状。Y和Gd的加入提高了消失模铸造AZ91D镁合金中α-Mg的初晶析出温度,降低其共晶温度。适量的Y和Gd能显著提高消失模铸造AZ91D镁合金的力学性能,当Y和Gd的含量分别为0.6%和0.9%时,抗拉强度、伸长率和硬度达到最大,分别为161.68MPa、2.80%、HB64.7,比不加Y和Gd的AZ91D镁合金分别提高了18.8%、54.7%、19.2%。 相似文献
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热处理对压铸AZ91D合金组织及硬度的影响 总被引:1,自引:0,他引:1
研究在线淬火、离线固溶处理(420℃×1 h在水中快冷)和时效处理(190℃×4 h空冷)对压铸AZ91D镁合金组织及硬度的影响。结果表明:在线淬火和离线的时效处理可提高压铸AZ91D合金的布氏硬度,但是离线固溶处理使合金硬度下降;在线淬火和时效处理后合金的组织与压铸AZ91D基本相同,仍由α-Mg及β-Al12Mg17组成。在压铸镁合金冷却过程中在线淬火使温度急剧降低,增强了Al元素固溶强化的效果;而时效处理通过Al12Mg17分解后重新析出并细化了晶粒,增强了细晶强化的效果。离线的固溶处理Al12Mg17分解后虽然固溶强化效果增强但是晶界强化相大幅减少,导致合金硬度降低。 相似文献
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目的 研究热处理对激光选区熔化成形(Selective Laser Melting,SLM)AZ91D镁合金组织与耐蚀性能的影响.方法 利用SLM技术成形了AZ91D镁合金,对试样进行固溶处理(T4)、固溶+时效处理(T6).采用金相显微镜、扫描电镜、X射线衍射仪、电化学工作站分别对SLM、T4热处理、T6热处理的AZ91D镁合金试样的微观组织和耐蚀性能进行观察与测试.结果 SLM试样经420℃保温6 h固溶处理后,β-Mg17Al12相基本固溶于基体中,晶粒尺寸由5μm增大至60μm左右.加热至200℃保温2 h时效处理后,β-Mg17Al12相从基体析出,随着时效时间由2 h增加至6 h,析出相数量逐渐增多.在3.5%NaCl溶液中浸泡120 h后,SLM试样表面腐蚀坑较小;T4热处理试样表面出现较大的腐蚀坑;T6热处理试样的表面腐蚀坑大小及深浅不一,腐蚀最严重.极化曲线结果表明,SLM试样的腐蚀电流密度Jcorr最小,为(1.889±0.2)×10–5 A/cm2,耐蚀性能最好;固溶+时效处理2 h的试样Jcorr最大,为(1.225±0.2)×10–4 A/cm2,耐蚀性能最差.不同热处理试样的耐蚀性能优劣排序为:SLM试样>T4试样>T6试样.结论 未经热处理的SLM试样晶粒尺寸最小,耐蚀性最好.经420℃保温6 h固溶处理后,β-Mg17Al12相基本溶解,晶粒尺寸增大1个数量级;加热至200℃时效2 h处理后,耐蚀性最差,当时效时间继续延长至6 h后,β-Mg17Al12相的数量逐渐增多,耐蚀性能反而有所增强. 相似文献
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300℃等温处理时间对AZ91D压铸镁合金组织和性能的影响 总被引:7,自引:2,他引:7
比较了AZ91D铸造镁合金与压铸镁合金材料的显微组织,并通过扫描电镜(SEM)、X射线衍射(XRD)以及金属拉伸试验等对压铸镁合金在300℃等温处理不同时间的组织结构及性能进行了研究.研究发现,AZ91D镁合金的铸件与压铸件组织均由α-Mg相与沿α相连续分布的β-Mg17Al12相组成,而且,铸造组织的β相较压铸组织粗大.压铸材料经过300℃、60h长时间等温热处理后,合金显微组织中β相发生了粗大化和颗粒化,由此产生的固溶强化作用使材料的抗拉强度σb、屈服强度σ0.2等力学性能随着等温热处理时间的延长先升高后降低,然而,弹性模量则逐渐变大.此外,由于组织中β相的颗粒化使其在组织中呈现不连续分布,引起了材料硬度HV和伸长率δ的降低. 相似文献
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通过对AZ91镁合金进行不同工艺的固溶处理和时效处理,研究了热处理工艺对AZ91镁合金显微组织、力学性能和耐腐蚀性能的影响。结果表明,固溶和时效处理可以明显提高AZ91镁合金的力学性能和耐腐蚀性能。分级固溶处理可使AZ91镁合金的抗拉强度提高27 MPa,-20℃冲击吸收功增加10 J,腐蚀电位正移196 mV。 相似文献
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热处理对细晶AZ91D镁合金组织和性能的影响 总被引:2,自引:0,他引:2
采用MEF-3金相显微镜、JSM-6700F扫描电镜、EMPA-1600电子探针以及WDW-100D型电子万能实验机等,对经Al-Ti-B细化处理的AZ91D镁合金铸态组织及固溶-时效态的显微组织和力学性能进行了观察和分析。结果表明:分布在铸态AZ91D镁合金晶界的网状β-Mg17Al12相在T4热处理过程中逐渐溶解,使得合金的硬度下降,而抗拉强度升高;T6热处理后,合金组织中出现不连续析出与连续析出的β-Mg17Al12相,使得抗拉强度和硬度明显提高;不同的热处理使合金的断口发生明显变化。 相似文献
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C. Zhang W. Cao S.-L. Chen J. Zhu F. Zhang A. A. Luo R. Schmid-Fetzer 《JOM Journal of the Minerals, Metals and Materials Society》2014,66(3):389-396
Precipitation simulation of AZ91 (Mg-9Al-1Zn; all compositions are in wt.% unless otherwise stated.) magnesium alloy is carried out in this work using the PanPrecipitation module of Pandat? software. In addition to the software, the thermodynamic database, mobility database, and precipitation database for AZ91 were developed to perform the simulation. The simulated results, such as the number density and particle size of the γ-Mg17Al12 precipitate, showed good agreement with the experimental data. Moreover, the simulated results were then used as input for the prediction of yield strength and micro-hardness of AZ91 aged at different temperatures, which also agreed well with experimental results. To demonstrate the applicability of the databases developed for AZ91, simulations were also carried out for two compositions with lower and higher Zn content. The simulated hardness showed reasonable agreement with the published experimental data. 相似文献
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Rheo-diecasting of AZ91D magnesium alloy 总被引:1,自引:0,他引:1
A rheo-diecasting process (RDC) was investigated for semisolid processing of an AZ91D magnesium alloy. The results of the
RDC samples in as-cast state indicate that the microstructure of primary α-Mg particles has a fine size, nearly spherical
morphology, and uniform distribution throughout the components. Due to the advanced microstructure and reduced level of defects,
the RDC AZ91D Mg alloy exhibits an apparent improvement in mechanical properties. The quantitative metallographic investigations
reveal that increasing the intensity of forced convection during the slurry preparation results in a promoted nucleation and
reduced volume fraction of the primary phase solidified in the slurry maker. 相似文献
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The corrosion performance of sand cast MEZS, zirconium-grain-refined MEZR, sand cast AZ91S, and high pressure diecast AZ91D magnesium alloys were evaluated by means of salt spray testing, optical metallography, hydrogen evolution, polarisation curve measurement and AC impedance spectroscopy. The results show that the corrosion resistance of the four alloys can be ranked in decreasing order as AZ91D > AZ91S ≈ MEZR > MEZS and that the intergranular phases and chemical composition of the matrix phase have a significant influence on the corrosion performance. Alloys with a finer grain size and higher aluminum or zirconium contents exhibit better corrosion resistance. 相似文献
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A simple furnace test explored ignition of three Mg alloys. WE43 had the highest ignition temperature (644 °C) compared with 628 °C for AZ31 and 600 °C for AZ91. Tests to measure the ignition temperature appear to be highly controlled. However, this appearance is deceptive because the ignition temperature depends on test details. Flame tests appear to be able to allow direct study of the behaviour in a flame and so appear to be a good approach to study the behaviour Mg alloys in an aircraft fire accident. 相似文献
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混杂增强AZ91镁合金基复合材料 总被引:1,自引:3,他引:1
采用挤压铸造成形法,成功地制备了具有不同含量与粒度的石墨颗粒与氧化铝短纤维混杂增强的镁合金基复合材料.对制备工艺、复合材料的显微组织及性能进行了研究,结果表明,增强相在复合材料中分布均匀,基体和增强相界面结合紧密,无明显铸造缺陷.复合材料的硬度随石墨含量的增加而降低,随石墨颗粒尺寸的细化而增大. 相似文献
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Initiation and early propagation of pitting and filiform corrosion on bare alloy AZ91 (9% Al, 1% Zn) are investigated by natural immersion corrosion tests, electrochemical measurements and microanalytical studies. Initiation sites are few. Corrosion spreads from these sites first in the form of filiform corrosion for a limited period of time and pitting which later develops into a cellular type of etching. The important factors affecting filiform corrosion are temperature, material structure and degree of polarization at the anodic sites. Filiform attack on AZ91, unlike the classical mechanisms of filiform corrosion on coated metals, is driven by hydrogen evolution reaction on the cathodic sites of the surface, occurs under significant anodic control, propagates at a high, constant speed independent of degree of polarization along preferential paths determined by compositional and crystallographic factors, and is a temporary phenomenon under open circuit conditions. Pitting corrosion is more predominant with decreasing anodic polarization. 相似文献
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D. Peixoto Barbosa 《Surface & coatings technology》2009,203(12):1629-1636
Anodic oxide films were grown on the Mg-Al-Zn alloy AZ91 in NaOH-solution and examined by electron microscopy, X-ray diffraction and micro-Raman spectroscopy. The anodic film consists of an inner barrier layer and an outer porous layer. The thin barrier layer is hydrated or contains Mg(OH)2. The porous layer was identified as crystalline MgO (periclase) and contains tunnels formed by breakdown/repair events, which involve plasma-electrolytic reactions. The micro-Raman-spectrum indicates the formation of a highly disordered zone around the tunnels. Applied current density, potential limit, electrolyte concentration and alloy phase were identified as parameters which have an influence on density and diameter of the tunnels. 相似文献