共查询到20条相似文献,搜索用时 9 毫秒
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通过OM、SEM和XRD对触变成形并经5年自然时效的铸态ZA27合金的微观组织进行了观察。结果表明:经触变成形后的ZA27合金由近球状初生粒子α′相和晶间的二次凝固组织组成。其中α′相主要有两种形态:一是颗粒内部存在"小液池";二是颗粒内部比较均匀,不存在二次凝固组织。晶间的二次凝固组织也以两种形态存在:一是在共晶边缘处形成体积不均的"孔洞"或是"孔洞"串在一起形成的"沟";二是在共晶内部已经分解为层片组织的大"孔洞"。共晶方式主要为离异共晶及其中"蜂窝"状棒状共晶,部分区域出现不规则层片共晶。 相似文献
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Yaohua Zhu Suet To Xianming Liu Guoliang Hu 《Metallurgical and Materials Transactions A》2011,42(7):1933-1940
The effects of static electropulsing on the phase transformations and elongation of a cold-deformed Zn-Al based alloy wire (ZA22) were studied using scanning electron microscopy (SEM) and electron backscattered diffraction (EBSD) techniques. Based on the transmission electron microscopy (TEM) determined lattice parameters of the phases involved, the electropulsing induced circular phase transformations were detected in the alloys using EBSD, which were never reported in any thermal and thermomechanical treated alloys. An adequate static electropulsing favored improving the identities of dislocation and microstructures (including the precipitation of the second phase, the residual stress, etc.), which resulted in enhancement of the plastic elongation of the alloy. 相似文献
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研究了ZA27铸造合金中的常见微量元素以及铸件厚度、浇注温度、变质处理对ZA27合金凝固特性的影响。实验结果表明,铸件厚度是影响ZA27合金凝固特性的最主要因素,适量的Ti可以改善ZA27合金的凝固特性,浇注温度及变质处理对ZA27合金的凝固特性也有不同程度的影响。根据实验结果,推荐了较佳工艺参数。 相似文献
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通过恒应变压缩实验研究了锻态TC10钛合金的高温变形行为和组织演变规律,变形温度为800~920℃,应变速率为0.01~10 s~(-1),变形量为60%。研究结果表明:降低变形温度、提高应变速率,流变应力会在变形初期迅速增加,而显微组织没有明显变化,当流变应力达到最大值后随着动态再结晶的发生而逐渐降低。提高变形温度、降低应变速率,能够为动态再结晶提供能量,细化组织并降低流变应力。综合分析表明:在变形温度为840~900℃,应变速率为0.01~0.1 s~(-1)的参数范围内进行热变形可以获得性能优良的TC10钛合金产品。 相似文献
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研究了热加工工艺对医用TC4合金大规格棒材显微组织的影响。研究结果表明:采用单一的拔长变形方式或单一的镦拔变形方式,不能全面解决医用TC4合金大规格棒材生产过程中经常出现的显微组织不均匀和成品率低下等问题;采用温度梯度镦拔组合变形工艺(Tβ+(30~70)℃镦拔,变形量50%→Tβ-(10~30)℃镦拔,变形量50%→Tβ-(30~70)℃镦拔,变形量50%),可以有效改善精锻用原始棒坯的组织,从而获得具有均匀细小等轴组织的医用TC4合金70 mm棒材。 相似文献
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采用粉末冶金法制备TZM合金,通过SEM和EDS检测手段观察其显微组织,并在此基础上分析TZM合金的三种强化,即固溶强化、第二相强化和形变强化的强化机理. 相似文献
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钛合金Ti8LC是一种新型低成本近а型的钛合金,为了研究该合金热处理对其组织结构的影响规律,对其进行不同温度固溶处理,随后在不同温度进行时效热处理.用金相显微镜和扫描电镜观察了不同热处理工艺下的微观组织形貌,并通过能谱分析了不同工艺下元素的含量变化.采用洛氏硬度计测试了试样的平均硬度,分析了固溶温度和时效温度对其微观组织形态的变化影响,以及硬度大小、微观组织结构中相的形态和组织组成的相关性.结果表明:固溶处理温度对Ti8LC固溶后的显微组织及随后的时效组织都有极大的影响,随固溶温度的升高,由片状逐渐转为块状.经相同时效工艺处理的合金其显微组织受固溶后组织的遗传影响,合金的硬度随着固溶温度的升高.先降低后升高;通过微观组织和硬度的良好配合,可以确定Ti8LC合金固溶时效的最佳工艺. 相似文献
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Bharat K. Jasthi William J. Arbegast Stanley M. Howard 《Metallurgical and Materials Transactions A》2012,43(9):3192-3201
The effect of thermal aging on the corrosion and microstructure of friction-stir welded (FSW) alloy 22 was investigated. Successful welds were produced with a polycrystalline cubic BN pin tool at a rotational speed of 200 rev min?1 and travel speed of 12.7 mm min?1. Topologically closed packed (TCP) phases of ~50 to 300 nm size were identified in the weld nugget. The area fraction of the TCP phases in the weld nugget increased with aging temperature and time. General corrosion rates measured from the weight loss experiments for welds were relatively higher than for parent material. The corrosion rates increased with the increased aging temperature and time. Intergranular corrosion (IGC) resistance is greater in friction-stir welds compared with the parent material at all aging temperatures and times. The IGC depth increased with the aging temperature and time in the parent material. The IGC depth for the FSW weld nugget was minimal and did not change with thermal aging. 相似文献
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对先进超超临界燃煤发电机组锅炉高温部件候选材料617合金在750℃下时效1000,2000,3000和5000h后试样的组织稳定性进行了研究。通过OM,SEM,TEM和X射线衍射等方法对时效后晶界及晶粒内的析出物进行了分析。研究发现,时效后试验材料的晶界析出M23C6碳化物;晶内析出γ′相,且γ′相呈颗粒状弥散分布,γ′相尺寸随时效时间的延长而增长。经1000h时效后,试验材料的强度开始增加,并且随着时效时间的延长,强度开始呈现平稳趋势。随着时效时间的延长,试验材料的韧性呈下降趋势。 相似文献
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《Canadian Metallurgical Quarterly》2013,52(4):503-512
AbstractIn this paper, the microstructure of slowly solidified ZA102 (Mg-10%Zn-2%Al), ZA104 (Mg-10%Zn-4%Al) and ZA106 (Mg-10%Zn-6%Al) magnesium alloys was characterized. Thermal analysis was performed to determine the solidification events which occur upon cooling. The results show that these alloys contain α(Mg) and a variable fraction of intermetallic phases: in ZA102 alloy, Mg32(Al,Zn)49 (τ) and MgZn (ε) are observed; in ZA104 alloy, τ is the only intermetallic phase formed; in ZA106 alloy, Al2Mg5Zn2 (Φ) and a small amount of the phase τ are found. It is suggested that the ternary phase τ could play an important role in the improvement of the creep resistance of alloys in the Mg-Zn-Al system. The results also show that the solidification range of these alloys decreases with an increase of aluminum contentDans ce document, on caractérise la microstructure de ZA102 (Mg-10%Zn-2%Al), de ZA104 (Mg-10%Zn-4%Al) et de ZA106 (Mg-10%Zn-6%Al), des alliages au magnésium solidifiés lentement. On a effectué une analyse thermique afin de déterminer les événements de solidification qui se produisent lors du refroidissement. Les résultats montrent que ces alliages contiennent du (Mg)-α et une fraction variable de phases intermétalliques: dans l'alliage ZA102, on observe du Mg32(Al,Zn)49 (τ) et du MgZn (ε); dans l'alliage ZA104, le t est la seule phase intermétallique formée; dans l'alliage ZA106, on trouve du Al2Mg5Zn2 (Φ) et une petite quantité de phase τ. On suggère que la phase ternaire τjoue un rôle important dans l'amélioration de la résistance au fluage d'alliages du système Mg-Zn-Al. Les résultats montrent également que la plage de solidification de ces alliages diminue avec une augmentation du contenu en aluminium. 相似文献
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Zheng Deshuang Chen Ruirun Ma Tengfei Ding Hongsheng Su Yanqing Guo Jingjie Fu Hengzhi 《Metallurgical and Materials Transactions A》2018,49(2):537-549
The coupling effects of melt treatment and ultrasonic treatment on the solidifying microstructure and mechanical performance of Ti44Al6Nb1Cr alloy are investigated. During melt treatment, a low superheat degree is beneficial for microstructure refinement, with the lamellar colony size decreasing from 512 to 243 μm, while a low cooling rate leads to the microstructure coarsening as the lamellar colony size enlarges from 458 to 615 μm. After coupling with ultrasonic treatment, under moderate superheat degree and cooling rate, the original coarse lamellar colony size is significantly refined to 56 and 38 μm, the compressive strength is improved by 60.71 and 47.89 pct, and the compressive strain is enlarged by 80.19 and 112.33 pct, respectively. It is found that the ultrasonic refining efficiency is dominated by the melt temperature, and there is an optimum temperature range near the crystallization temperature: a too-high temperature leads to the remelting of crystal nuclei, impairing the refining efficiency, whereas a too-low temperature results in high viscosity, hindering the ultrasonic effects. Under ultrasonic treatment, the melt supercooling is increased, leading to an extended constitutional supercooling region, which will enlarge the crystal nucleation; the solute enrichment is enhanced, forming a quasi-steady state with a higher solution concentration gradient, which improves the crystal growth velocity. 相似文献
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采用金相显微镜、X-射线衍射仪、差热分析仪及扫描电镜等设备分析了新型镁合金颗粒相和Zr质点。H相、W相主要分布在晶界,Mg2Sn颗粒相弥散分布在晶粒内部,Zr起到ZW22的显微组织和相组成.结果表明:ZW22镁合金中主要存在α-Mg、H相、W相、Mg2Sn非均质形核的作用。 相似文献