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1.
自Al基金属玻璃被发现以来,其较弱的玻璃化能力以及较强的脆性一直是阻碍其发展的主要因素。目前,金属玻璃的形成机制和结构模型等理论尚不完善。从金属玻璃形成能力判据,Al基金属玻璃的力学、热稳定性等性能以及制备方法等方面综述了Al基金属玻璃的最新研究进展。  相似文献   

2.
自AI基金属玻璃被发现以来,其较弱的玻璃化能力以及较强的脆性一直是阻碍其发展的主要因素。目前,金属玻璃的形成机制和结构模型等理论尚不完善。从金属玻璃形成能力判据,Al基金属玻璃的力学、热稳定性等性能以及制备方法等方面综述了Al基金属玻璃的最新研究进展。  相似文献   

3.
为了揭示Ni和Y元素对Al-Ni-Y三元金属玻璃的玻璃形成能力影响的本征机理,且基于费米面和伪布里渊区理论,提出了Ni和Y元素对Al-Ni-Y三元金属玻璃的玻璃形成能力的影响分为两种情况:Ni原子通过Al和Ni原子之间的电子轨道杂化效应,改变费米面直径(2KF),从而影响Al基金属玻璃的玻璃形成能力;Y原子通过整体原子的静态结构,改变伪布里渊区(KP),最终影响Al基金属玻璃的玻璃形成能力.费米面和伪布里渊区尺寸通过电子能量损失谱(EELS)、X射线衍射(XRD)和X射线光电子能谱(XPS)获得.研究表明,当两者相互作用机制满足2KF=KP,条件时,费米能级处电子态密度最低,金属玻璃整体结构的稳定性达到最佳.在此基础上,提出了δ=KP-2KF判据用于衡量Al-Ni-Y三元金属玻璃的玻璃形成能力,该判据在实验上得到验证.  相似文献   

4.
《现代材料动态》2005,(11):19-20
中科院金属所研制出世界上强度最高和具有强玻璃形成能力的镁合金,这一研究成果使中国在此领域跃居国际先进水平,对推动镁基金属玻璃作为新一类轻质高强度材料的应用具有重要意义。  相似文献   

5.
王胜海  杨春成  边秀房 《材料导报》2012,26(1):88-93,98
Al基非晶合金及纳米Al基非晶合金材料发展十分迅速,具有广阔的应用前景。综述了Al基非晶合金的制备、形成机制、玻璃形成能力、过热熔体脆性和块体Al基非晶合金及纳米Al基非晶复合材料的制备与性能等热点问题。  相似文献   

6.
据媒体报导,中国科学院金属所不久前研制出目前世界上强度最高和具有强玻璃形成能力的镁合金。该研究成果使中国在此领域跃居国际先进水平,对推动镁基金属玻璃作为新一类轻质高强度材料的应用具有重要意义。  相似文献   

7.
镁基金属玻璃的形成能力及塑性研究进展   总被引:1,自引:0,他引:1  
许春霞  潘复生  王敬丰 《材料导报》2007,21(7):67-69,78
相对于晶态镁合金,镁基金属玻璃因其高强度、耐腐蚀性等特性,近年来引起了人们的普遍关注.然而它较低的玻璃形成能力及室温脆性却是其走向工业应用的瓶颈,因此该领域的研究主要集中于通过成分设计、添加第二相等方法来提高其玻璃形成能力和塑性.综述了其最新研究进展并提出了当前的研究重点.  相似文献   

8.
铝基非晶合金具有密度低、强度高、耐腐蚀等诸多优异性能;然而,铝基非晶合金形成能力差,一般需要非常高的冷却速率,这限制了铝基非晶合金的应用.玻璃形成理论认为形成能力与过冷液体密切相关.但在一般升温测量时,铝基非晶合金不显示玻璃转变或过冷液体,而是直接变成晶态.目前为止,关于铝基非晶合金的玻璃转变和过冷液体属性仍然是未知的.本文采用超快速差热分析方法(Flash DSC)使得升温速度达到10000 K s^-1,测量了20余种常见铝基非晶合金的玻璃转变行为和过冷液体特征.发现铝基非晶合金普遍具有很高的液体脆度系数(m),其中某些成分m>160,已经接近理论上预测的脆度系数上限m^175.通过系统研究这些成分的形成能力,发现铝基非晶合金的玻璃形成能力与脆度系数成反相关,而且这种相关不是线性的.只有m<100时,降低m才会对玻璃形成能力有明显影响;相反, m>100的玻璃形成力普遍较弱,而且随m变化不显著.因此,过高的液体脆度系数可能是铝基非晶合金形成能力差的一个重要原因.  相似文献   

9.
《现代材料动态》2009,(8):23-23
20世纪80年代,美国弗吉尼亚大学Pooh研究组和日本东北大学Inoue研究组分别发现越基合金可通过快速凝固技术形成非晶态结构。Al基非晶态合金及其部分结晶后形成的纳米复合薄带材料表现出超高的比强度(5.2&#215;10^5Nmkg^-1)及良好的塑性,被认为是极具应用前景的新一代超高强度轻质合金。然而,与Pd、Mg、Zr、Fe等合金相比,灿基合金的玻璃形成能力较低,无法通过熔体浇铸直接形成尺度大于1mm的块体材料。舢基金属玻璃块体材料的获得主要依赖于粉末固结的途径。探索具有高玻璃形成能力、可通过熔体直接浇铸形成块体材料的合金体系始终是人们追求的目标。  相似文献   

10.
选取了具有良好化学稳定性的Al-Ca-Ba玻璃系统作为闪烁体的基质系统,研究了Ce3+在该玻璃系统中的发光特性以及该玻璃系统中A/C(Al2O3/CaO)比值对发光性能的影响。研究结果表明,Ce3+在Al-Ca-Ba玻璃系统中的发光较其它玻璃系统激发与发射波长均发生了明显的红移效应,Stokes位移变大,原因跟该玻璃系统较高的光碱度相关;Al-Ca-Ba玻璃闪烁体中A/C比值对发光性能具有非常重要的影响,其比值处于12CaO.7Al2O3这一低熔区域范围内,发光性能最好。  相似文献   

11.
High entropy metallic glasses (MGs) have attracted tremendous attentions owing to high entropy that benefits the probing of new MG-forming systems. However, the micro-formability of high entropy MGs is lack of investigation in comparison with these conventional MG counterparts, which is crucial to the development of this kind of metallic alloys. In this work, the thermoplastic mciro-formability of TiZrHfNiCuBe high entropy MG was systemically investigated. Time-Temperature-Transformation (TTT) curve was first constructed based on isothermal crystallization experiments, which provides thermoplastic processing time of the supercooled high entropy MGs. By comparison with the deformation map, Newtonian flow was found beneficial to the thermoplastic formability. While the thermoplastic forming becomes arduous with reducing mould size to tens micrometer, because of the strong supercooled TiZrHfNiCuBe high entropy MG (fragility = 27). Fortunately, the micro-formability of TiZrHfNiCuBe high entropy MG could be improved by vibration loading, as demonstrated by finite-element-method simulation. Our findings not only systemically evaluate the thermoplastic micro-formability of high entropy MG, but also provide fundamental understanding of the phenomenon.  相似文献   

12.
It is a long-standing challenge to search for metallic glasses(MGs)with optimal combinations of glassforming ability(GFA),strength and toughness in the vast compositional space.By taking into account both recently developed ellipse criterion and temperature-based GFA criterion,here we established quantitative correlations among compositions,elastic constants,GFA and mechanical properties of MGs,which enable to predict the GFA,fracture strength and fracture surface simultaneously in advance once the compositions of MGs are determined.Experimental data confirm the validity of this approach in prediction.Finally,a strategy for designing MGs with optimal combinations of strength,toughness and GFA is proposed,which allows for high-throughput discovering glass formers with excellent mechanical properties.  相似文献   

13.
Polyamorphs are often observed in amorphous matters, and a representative example is the reentrant glass transition in colloid systems. For metallic amorphous alloys, however, the cases reported so far are limited to metallic glasses (MGs) that undergo electronic transitions under gigapascal applied pressure, or the presence of two liquids at the same composition. Here we report the first observation of a reentrant glass transition in MGs. This unusual reentrant glass transition transforms an MG from its as-quenched state (Glass I) to an ultrastable state (Glass II), mediated by the supercooled liquid of Glass I. Specifically, upon heating to above its glass transition temperature under ambient pressure, Glass I first transitions into its supercooled liquid, which then transforms into a new Glass II, accompanied by an exothermic peak in calorimetric scan, together with a precipitous drop in volume, electrical resistance and specific heat, as well as clear evidence of local structural ordering on the short-to-medium-range scale revealed via in-situ synchrotron X-ray scattering. Atomistic simulations indicate enhanced ordering of locally favored motifs to establish correlations in the medium range that resemble those in equilibrium crystalline compounds. The resulting lower-energy Glass II has its own glass transition temperature higher than that of Glass I by as much as 50 degrees. This route thus delivers a thermodynamically and kinetically ultrastable MG that can be easily retained to ambient conditions.  相似文献   

14.
When bulk materials are made into micro‐and nanoscale fibers, there will be attractive improvement of structural and functional properties, even unusual experimental phenomena [Ref. 3 ]. The main drawback of various applications of metallic fibers is poor ability of present fabrication methods for controlling their dimensions and surface properties [Ref. 4 ]. Metallic glassy fibers (MGFs) are desired because of unique mechanical and physical properties and glass‐like thermoplastic processability of metallic glasses (MGs). Here, we report a synthetic route for production of micro‐to nanoscale MGFs (the diameter ranges from 100 µm to 70 nm) by driving bulk metallic glass rods in their supercooled liquid region via superplastic deformation. Compared with existing metallic fibers, the MGFs have precisely designed and controlled properties and size, high structural uniformity and surface smoothness, and extremely flexibility. Remarkably, the method is simple, efficient, and low cost, and the MGFs can be continuous prepared by the method. Furthermore, the MGFs circumvent brittleness of MGs by size reduction. We proposed a parameter based on the thermal and rheological properties of MG‐forming alloys to control the preparation and size of the fibers. The MGFs with superior properties might attract intensive scientific interest and open wide engineering and functional applications of glassy alloys.  相似文献   

15.
The structure of metallic glasses (MGs) has been a long-standing mystery. On the one hand, MGs are amorphous materials with no long-range structural order; on the other hand, topological and chemical short-to-medium range order is expected to be pronounced in these alloys, due to their high atomic packing density and the varying chemical affinity between the constituent elements. The unique internal structure of MGs underlies their interesting properties, which render MGs potentially useful for various applications. While more and more glass-forming alloys have been developed in recent years, fundamental knowledge on the structural aspect of MGs remains seriously lacking. For example, how atoms pack on the short-to-medium range, how the structure differs in different MGs and changes with composition, temperature, and processing history, and more importantly, how the structure influences the properties of MGs, are still unresolved questions. In this paper, we review the tremendous efforts over the past 50 years devoted to unraveling the atomic-level structure of MGs and the structural origin of their unique behaviors. Emphasis will be placed on the progress made in recent years, including advances in structural characterization and analysis of prototypical MGs, general structural models and fundamental principles, and the correlations of thermodynamic, kinetic, and mechanical properties with the MG structures. Some widely observed property-property correlations in MGs are also examined from the structural perspective. The insights summarized are shown to shed light on many intriguing behaviors of the MG-forming alloys and expected to impact the development of MGs. Outstanding questions in this important research area will also be outlined.  相似文献   

16.
Metallic glasses, first discovered a half century ago, are currently among the most studied metallic materials. Available in sizes up to several centimeters, with many novel, applicable properties, metallic glasses have also been the focus of research advancing the understanding of liquids and of glasses in general.Metallic glasses (MGs), called also bulk metallic glasses (BMGs) (or glassy metals, amorphous metals, liquid metals) are considered to be the materials of the future. Due to their high strength, metallic glasses have a number of interesting applications, for example as coatings. Metallic glasses can also be corrosion resistant. Metallic glasses, and the crystalline materials derived from them, can have very good resistance to sliding and abrasive wear. Combined with their strength – and now, toughness – this makes them ideal candidates for bio-implants or military applications. Prestigious Journals such as “Nature Materials”, “Nature” frequently publish new findings on these unusual glass materials. Moreover Chinese and Asian scientists have also been showing an interest in the study of metallic glasses.This review paper is far from exhaustive, but tries to cover the areas of interest as it follows: a short history, the local structure of BMGs and the glass forming ability (GFA), BMGs’ properties, the manufacturing and some applications of BMGs and finally, about the future of BMGs as valuable materials.  相似文献   

17.
A multicomponent Al84Y9Ni4Co1.5Fe0.5Pd1 alloy was found to keep a mixed glassy + Al phases in the relatively large ribbon thickness range up to about 200 μm for the melt-spun ribbon and in the diameter range up to about 1100 μm for the wedge-shaped cone rod prepared by injection copper mold casting. The glassy phase in the Al-based alloy has a unique crystallization process of glass transition, followed by supercooled liquid region, fcc-Al + glass, and then Al + Al3Y + Al9 (Co, Fe)2 + unknown phase. It is also noticed that the primary precipitation phase from supercooled liquid is composed of an Al phase instead of coexistent Al + compound phases, being different from the crystallization mode from supercooled liquid for ordinary Al-based glassy alloys. In addition, it is noticed that the mixed Al and glassy phases are extended in a wide heating temperature range of 588–703 K, which is favorable for the development of high-strength nanostructure Al-based bulk alloys obtained by warm extrusion of mixed Al + amorphous phases. The Vickers hardness is about 415 for the glassy phase and increases significantly to about 580 for the mixed Al and glassy phases. The knowledge of forming Al + glassy phases with high hardness in the wide solidification and annealing conditions through high stability up to complete crystallization for the multicomponent alloy is promising for future development of a high-strength Al-based bulk alloy.  相似文献   

18.
开发具有优良性能的材料一直是人类不懈的追求.如果将尺寸放大到与传统金属相当的水平,金属玻璃将是一种理想的金属材料.为了应对这一挑战,在过去的几十年中,研究学者们已经尝试了多种方法,包括基于热力学的合金开发、3D打印以及基于人工智能学习的合金优化设计新理念.本文提出了一种简便、灵活的界面设计理念来制造直径大于100 mm的巨型金属玻璃(GMG),通过该方法制造的巨型金属玻璃性能几乎与铸态样品相同.此外,利用该方法可制造复杂三维结构.本文提出的方法为克服合金系统中长期存在的玻璃形成能力(GFA)限制的问题,制造大尺寸、复杂结构金属玻璃开辟了新的思路和途径.  相似文献   

19.
High-entropy alloys (HEAs) and metallic glasses (MGs) are two material classes based on the massive mixing of multiple-principal elements. HEAs are single or multiphase crystalline solid solutions with high ductility. MGs with amorphous structure have superior strength but usually poor ductility. Here, the stacking fault energy in the high-entropy nanotwinned crystalline phase and the glass-forming-ability in the MG phase of the same material are controlled, realizing a novel nanocomposite with near theoretical yield strength (G/24, where G is the shear modulus of a material) and homogeneous plastic strain above 45% in compression. The mutually compatible flow behavior of the MG phase and the dislocation flux in the crystals enable homogeneous plastic co-deformation of the two regions. This crystal–glass high-entropy nanocomposite design concept provides a new approach to developing advanced materials with an outstanding combination of strength and ductility.  相似文献   

20.
Metastable high entropy alloys(HEAs) and amorphous metallic glasses(MGs), with the chemical disordered character, are intensively studied due to their excellent performance. Here, we introduce Cu to separately constrain these two metastable materials and comparatively investigate their deformation behaviors and mechanical properties of Cu/HEA Fe Co Cr Ni and Cu/MG Cu Zr nanolaminated micropillars in terms of intrinsic layer thickness h and extrinsic pillar diameter D. The metastable HEA layers, as the hard phase in Cu/HEA micropillars, are stable and dominate the deformation, while transformation(crystallization) occurs in MG which plays a minor role in deformation of Cu/MG micropillars. The h-controlled deformation mode transits from the D-independent homogenous-like deformation at large h to the Ddependent shear banding at small h in both Cu/HEA and Cu/MG micropillars. Although both Cu/HEA and Cu/MG micropillars exhibit a maximum strain hardening capability controlled by h, the former manifests much lower hardening capability compared with the latter. The intrinsic size h and extrinsic size D have a strong coupling effect on the strength of Cu/HEA and Cu/MG micropillars. The strength of strength of Cu/HEA micropillars exhibits the D-dependent transition from "smaller is stronger" to "smaller is weaker"with increasing h. By contrast, the strength of Cu/MG micropillars exhibits the transition from bulk-like D-independent behavior at large h to small volume D-dependent behavior(smaller is stronger) at small h.  相似文献   

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