共查询到18条相似文献,搜索用时 125 毫秒
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目的 探究氮含量对MoTaW多主元合金薄膜的微观组织和力学性能的影响,并提高Mo-Ta-W多主元合金薄膜的力学性能。方法 采用反应多靶磁控溅射技术在单晶硅片上制备出了具有不同氮含量的Mo-Ta-W-N多主元合金氮化物薄膜,通过X射线光电子能谱仪、掠入射角X射线衍射、场发射扫描电子显微镜、原子力显微镜对薄膜的成分、组织结构、表面及截面微观形貌、厚度和粗糙度进行了表征分析,并采用纳米压痕仪对薄膜的硬度和弹性模量进行了测试。结果 Mo-Ta-W-N多主元合金氮化物薄膜中的氮含量随着溅射过程中氮气流量的增加而增加,当氮气流量达到50%时,薄膜中的氮含量升至49%,而钽含量则随之降低至12%。形成氮化物后,Mo-Ta-W多主元薄膜由BCC结构转变成了单相FCC固溶体结构,表面由层片状结构转变为花椰菜状团簇结构,随着氮含量的增加,表面的粗糙度先降低后升高,厚度则不断降低。与Mo-Ta-W多主元合金薄膜相比,Mo-Ta-W多主元合金氮化物薄膜的力学性能有所提高,但随着氮含量的增加而下降,当氮气流量为10%时,Mo-Ta-W-N多主元合金氮化物薄膜的硬度和弹性模量分别为34.3 GPa和327.5 GPa。结论 氮化物的形成对Mo-Ta-W多主元合金薄膜的相结构、表面形貌等有影响,可有效提高薄膜的力学性能。 相似文献
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高熵合金涂层由于具有优于块体高熵合金和传统金属涂层的综合性能,在航空航天、核反应堆等极端服役环境下表现出了巨大的应用潜力。涂层低维形态产生的尺寸效应与高熵合金独特的多主元特征效应相耦合,使高熵合金涂层具有成分均匀、组织致密、结构稳定、性能优异等特点。概述了近年来高熵合金涂层的主要制备技术,简述了不同制备方法的原理、优势及工艺参数对涂层组织性能的影响。探讨了高熵合金中主要组元元素的作用、相结构的调控准则、多相转变行为等微观组织结构的特征与影响机制。论述了高熵合金涂层的服役性能特点,包括力学性能、抗氧化、耐腐蚀、抗辐照及耐磨损性能,并分析了成分/工艺-组织-性能的关联及相关作用机理。最后,总结了目前研究工作中存在的关键科学难题与挑战,对高熵合金涂层的研究方向与应用前景进行了展望。 相似文献
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采用扩展X射线精细结构谱(EXAFS)研究了热处理对Mg65Cu25Gd10金属玻璃结构的影响,分析了力学性能与结构变化的相关性。结果表明:Mg6sCu2sGd10金属玻璃中主要存在两种短程有序Cu-Mg及Cu-Gd,两种短程有序在晶化过程中变化的机制不同。前者,化学与拓扑短程有序均发生了明显变化,而Cu-Gd以拓扑短程有序变化为主。Mg65Cu25Gd10金属玻璃在退火后力学性能的下降主要是由于Cu原子周围短程有序的增加(低温阶段)和晶相的出现(高温阶段)引起的。Gd原子局域结构在退火期间无明显变化,故其对力学性能的变化影响较小。 相似文献
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高熵合金是一种原子排列有序,化学无序的新型多主元合金。通过改变合金元素的种类和浓度,能够调控合金系统层错能及显微组织的相稳定性,进而诱发形变孪晶、马氏体相变等塑性变形机制,最终使合金获得突出的综合力学性能。这种高熵合金的设计理念称为“亚稳工程”。亚稳高熵合金的显微组织、相结构及变形机制与合金体系的层错能密切相关。在FeMnCoCr系亚稳高熵合金中,随着系统层错能降低,面心立方结构稳定性下降,从而激活应变诱导马氏体相变(γ→ε),实现了合金强度和塑性的同时提高。本文主要介绍了FeMnCoCr系亚稳高熵合金的成分设计、制备及加工方法、微观结构和力学性能,并对亚稳高熵合金未来的研究方向进行了展望。 相似文献
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由于非晶合金独特的无序结构,其结构动力学特征涉及较大时间与尺寸跨度的粒子重排。作为深入研究金属玻璃体系弛豫行为与老化动力学的基础,对非晶合金结构动力学的表征和理解至关重要。大量研究表明,以镧基和铈基为代表的稀土基非晶合金的弛豫谱呈现明显次级弛豫过程,该体系亦成为探究非晶合金结构动力学与力学性能关联的理想载体。本文主要就金属玻璃的滞弹性变形作了详细评述。作为蠕变实验中变形的主要成分,这类变形在卸载后可完全回复,对其合理描述是深入理解非晶合金结构动力学的关键。此外,总结了蠕变和蠕变回复过程中滞弹性变形的主要特征,并介绍了几种可用于定量或定性分析的理论模型。 相似文献
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The study on the deformation mechanism of titanium alloys is beneficial to revealing the influence of microstructure on mechanical properties, and then providing guidance for the optimization of microstructure and properties. For most near-α and α + β titanium alloys, slip is the dominant deformation mechanism. Therefore, investigating the slip initiation and slip transfer behavior, as well as crack nucleation mechanism, is essential to reveal the fundamental relationship between microstructure and mechanical properties. However, due to the coexistence of grain boundary and phase boundary in dual-phase microstructure of titanium alloys, the phase content, grain size, grain boundary misorientation and α/β orientation relationship would affect the slip initiation and transfer behavior, resulting in a very complex plastic deformation mechanism. Based on the previous investigations of deformation mechanism of near-α and α + β titanium alloys, this review first analyzed the sequence of slip initiation between α and β phases and discussed the main factors affecting the slip initiation in α phase. Secondly, the basic rule of slip transfer and the influence of different interfaces on slip transfer were reviewed. Finally, the mechanism of crack nucleation and effect of microstructure on crack nucleation were analyzed based on slip transfer behavior. 相似文献
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块体非晶合金用于工程结构材料的优势在于其高强度和高弹性应变,瓶颈在于其缺乏塑性。近期的研究进展表明,在非晶合金中引入微观结构的不均匀性,可以获得良好的室温塑性。本文综述了块体非晶合金中各种微观结构不均匀性的形成条件、表征手段以及微观结构不均匀性与剪切带行为和塑性的关系,讨论了制备条件和合金成分对非晶合金微观结构和塑性的影响,并提出了非晶领域未来需要解决的几个重要问题 相似文献
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《Acta Materialia》2008,56(19):5440-5450
This study demonstrates that elastostatic compression imposed on amorphous alloys at room temperature induces irreversible structural disordering. The rate of disordering depends on the atomic packing density as determined by the fraction of the material in short-range ordered (SRO) atomic environments. The structural disordering, measured experimentally by differential scanning calorimetry, in turn alters the mechanical properties of the material. A combination of experiments and molecular dynamics simulations are used to explore fundamental issues related to shear-induced disordering during elastostatic compression. 相似文献
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Fushi Jiang Chang Pang Zhaoyang Zheng Qing Wang Jijun Zhao Chuang Dong 《金属学报(英文版)》2020,33(7):968-974
Construction of suitable structural models in order to account for chemical short-range orders is the reason behind the difficult multi-scale computational simulation methods for solid solutions.Herein,using Ti-Mo alloys as representative,we used our cluster-plus-glue-atom model to address the chemical short-range orders for body-center cubic lattice.In accordance with the atomic interaction mode,an Mo solute atom would prefer 14 Ti solvent atoms as its nearest neighbors,forming a rhombic-dodecahedral cluster,and some next outer-shell Mo and Ti atoms would serve as the glue atoms,which is formulated as [Mo-Ti_(14)](Mo,Ti)_x.The number of glue atoms x corresponds to different spatial distribution of the clusters.One of the formula having good stability is [Mo-Ti_(14)]Mo,i.e.,with one Mo as the glue atom.To verify its stability,mechanical properties and electronic density of state are obtained using the first-principles calculations and the Young's modulus agrees with the experimental values.Also the formulated structural unit [Mo-Ti_(14)]Mo is indeed verified by the cluster expansion method.This work then confirms the existence of simple structural unit covering the nearest neighbors and a few next outershell atoms for the Ti-Mo alloy of high structural stability. 相似文献