非晶合金精细零部件的超塑性成形技术

对各种精细零部件成形方法进行了比较，介绍了典型大块非晶合金的特性，尤其是大块非晶合金在过冷温度域的超塑性成形性能，概述了目前国外已开发的非晶合金精细零部件超塑性成形技术及其在典型精细零部件成形方面的应用。     

非晶态合金焊接的研究进展

综述了近几年国内外非晶态合金在焊接方面的研究进展,简要分析了将大块非晶合金焊接成功的原因.目前可以成功焊接大块非晶合金的方法有:高压压实法、摩擦焊、闪光电阻焊、电子束焊、爆炸焊、激光焊.其中前两种焊接属于固相焊接,成功的原因主要是:块体非晶合金过冷液相区的热稳定性和超塑性.而其他几种属于液相焊接,成功的原因主要是:(1)非晶合金具有大的非晶形成能力;(2)焊接的能量高且集中,因而加热和冷却速度快于这些合金的临界冷却速度.大块非晶合金的焊接成功地推动了大块非晶合金在工程材料方面的应用.     

非晶合金热塑性微成型技术研究概况及发展趋势

由于非晶合金的无定形结构,非晶合金在室温下表现出高强度、高硬度、加工性能差等特征。但是,非晶合金在过冷液相区内展现出低粘滞系数、高流动性能的超塑性特征,这为非晶合金的塑性加工提供了一种新的途径。论述了非晶合金过冷液相区热塑性微成型技术的特点,对比传统晶态材料总结了非晶合金作为理想微成型材料的优势。介绍了非晶合金在微机电系统(MEMS)产业领域诱人的应用前景,并列举了国内外相关专家学者在非晶合金热塑性微成型领域的研究成果。总结了非晶合金在微电子系统、精密光栅、微纳超疏水表面、生物芯片、微型燃料电池等领域的应用。同时,指明了非晶合金热塑性微成型技术发展过程中存在的问题,重申了开发非晶合金热塑性微成型技术的重要性。     

大块非晶合金过冷液相区的超塑性流变行为

大块非晶合金在过冷液相区内较低应变速率变形条件下呈现出牛顿型流变状态,并获得最佳塑性.其流变机制为一种与聚合物体系及无机玻璃相似的动力学行为.由于在超塑性流变过程中非晶相伴随有晶化现象的发生,因此,大块非晶合金的粘滞流变是一种非晶相-晶化相复相结构的变形行为.     

近十年来块体非晶合金材料的研究现状及发展趋势

综述了现有的各种块体非晶合金（BMGs）体系及其主要性能特点、应用情况,分析了近十年来该领域的研究现状,认为当前的有关基础研究工作主要集中在新非晶合金体系的开发、不同变形方式下的变形行为及断裂机理、焊/连接工艺、复合强韧化、塑性成形及断裂过程的仿真模拟、微成形性能等几个方面;相关的应用研究,一是通过超塑性成型及各种连接技术实现常规尺寸非晶合金制件的加工;二是通过微塑性成型技术实现对微型器件的制造。最后,指出了实现非晶合金微型制件工业化、批量化生产所必须解决的几个关键问题。     

具有极大玻璃形成能力的多元大块非晶合金的研究进展

近十年来,一系列具有极大玻璃形成能力,极低的临界冷却速度的大块非晶合金相继被发现,各种新研制出的大块非晶合金有两个共同的特征：（１）具有多元合金成分;（２）具有较大的过冷液相区范围。本文综合评述了大块非晶合金的研究进展,最新成果,着重讨论了多元合金的玻璃形成能力及其改善途径。     

ZT3非晶合金在过冷液相区的塑性变形研究

目的 研究不同的应变速率和变形温度对Zr30.2Ti32.9Cu9Ni5.3Be22.6非晶合金(亦称ZT3)在过冷液相区塑性变形行为的影响。方法 首先，用真空非自耗电弧炉熔炼合金锭并吸铸成直径为8 mm、长度为60~80 mm的非晶合金圆棒;然后，通过等温晶化试验确定ZT3非晶合金在过冷液相区中对应不同温度时发生晶化转变所需的最短时间，并用热模拟试验机进行压缩变形的试验研究;最后，用X射线衍射仪测试ZT3非晶合金在过冷液相区塑性变形后的组织特性。结果 ZT3非晶合金在过冷液相区内的塑形变形行为与应变速率和变形温度有密切的关联性。不同的应变速率与变形温度都会对其塑性变形产生影响，但变形温度的影响比恒定应变速率更大。对ZT3非晶合金变形后的结构分析发现，应变速率对非晶态结构的影响大于温度。结论 ZT3非晶合金的等温晶化转变孕育时间最短为17 min，在小于17 min的时间内完成塑性变形即可抑制晶化转变的发生。当恒定应变速率为2×10^?3 s^?1时，将变形温度控制在355~375 ℃范围内有利于ZT3非晶合金在过冷液相区进行热压塑性成形。     

粉末冶金制备大块非晶合金研究进展

粉末冶金作为制备大块非晶合金的主要方法之一,与快速冷凝相比,该方法可以在更广的合金系、更宽的成分范围内制备出尺寸更大、形状复杂、近净成形的大块非晶合金材料,因此粉末冶金是一种极具前景的大块非晶合金的制备方法.简要介绍了粉末冶金制备大块非晶合金的基本过程,详细阐述了各种成形技术的特点、原理、优缺点以及制备大块非晶合金的研究进展,期望为非晶、纳米晶粉末的致密化研究和制备大块非晶合金提供技术指导.     

具有大过冷液相温度区间的Cu基大块非晶合金的制备和机械性能

利用铜模铸造方法制备了具有大过冷液相温度区间的Cu-Zr-Ti-Ni系高强度Cu基大块非晶合金,对于Cu55Zr55Ti15Ni5合金,最大直径达5mm.过冷液相区温度范围ΔTx达45.48～70.98 K.Cu基玻璃合金棒表现出非常高的机械性能和明显的塑性,对于Cu50Zr25Ti15Ni10、Cu55Zr25Ti15Ni5和Cu54Zr22Ti18Ni6合金,压缩断裂强度分别达2155MPa、2026MPa和1904MPa,维氏硬度分别达674、678和685.加入Co元素扩大了CuZr-Ti-Ni系合金的ΔTx,Cu50Zr22Ti18Ni6Co4合金的ΔTx高达74.5K.     

Fe基大块非晶合金塑性的研究进展

Fe基大块非晶合金因其优良的性能和成本优势已引起研究者的广泛关注,但脆性极大的缺陷阻碍其走向工程应用。综述了Fe基大块非晶合金塑性研究领域的最新进展,分析了其脆性产生的机理。介绍了目前常用的对Fe基大块非晶合金进行塑性增韧的方法,即成分设计法(微合金化)和添加第二相增韧法,提出了当前研究的重点。     

高强度Cu基块状非晶合金的最新研究进展

Cu基块状非晶合金是一种新型高性能材料,从合金体系、力学性能、合金过冷液体区域的性能及非晶形成能力几方面对Cu基块状非晶合金的最新研究进展进行了综述,并展望了新型Cu基块状非晶合金的工程应用前景.     

Glass-Forming Ability for Nd_(70-x)Fe_(20)Al_(10)Y_x and Nd_(60-x)Fe_(30)Al_(10)Y_x Alloys

The glass-forming ability (GFA) of Nd70-xFe2oAl10Yx and Nd60-xFe30Al10Yx (0< x <15) alloys produced by Cu mold casting was investigated. Except Y=5 at. pct, bulk amorphous Nd70-xFe20Al10Yx alloys up to 2 mm in diameter were obtained. The GFA for Nd60-xFe30Al10Yx alloys, however, was found to decrease with increase of Y due to the increasing compositional deviation from the original eutectic point of Nd60Fe30Al10 alloy. The Nd60Fe20Al10Y10 and Nd60Fe30Al10 alloy exhibit the largest GFA and can be cast into bulk amorphous cylindrical specimens of 3 mm in diameter. The melting temperature or/and the reduced crystallization temperature is closely related to the GFA of Y-containing alloys. The bulk amorphous cylinder for the Nd55Fe20Al10Y15 alloy shows a distinct glass transition temperature and a wide supercooled liquid region before crystallization. The crystallization temperature, Tg, and the supercooled liquid region, TX, are 776 K and 58 K, respectively. The GFA and thermal stability of the Nd-Fe-AI-Y a     

Glass-Forming Ability for Nd70-xFe20AlioYx and Nd60-xFe30Al10Yx Alloys

The glass-forming ability (FGA) of Nd70-xFe20Al10Yx and Nd60-xFe30Al10Yx(0≤x≤15) alloys produced by Cu mold casting was investigated.Except Y=5 at.pct,bulk amorphous Nd70-xFe20Al10Yx alloys up to 2mm in diameter were obtained.The GFA for Nd60-xFe30Al10Yx alloys,however,was found to decrease with increase of Y due to the increasing compositional deviation from the original eutectic point of Nd60Fe30Al10 alloy.The Nd60Fe20Al10Y10 and Nd60Fe30Al10 alloy exhibit the largest GFA and can be cast into bulk amorphous cylindrical specimens of 3mmm in diameter.The melting temperature or /and the reduced crystallization temperature is closely related to the GFA of Y-containing alloys.The bulk amorphous c ylinder for the Nd55Fe20Al10Y15 alloy shows a distinct glass transition temperature and a wide supercooled liquid region before crystallization.The crystallization temperature,Tg,and the supercooled liquid region,ΔTx,are 776K and 58K,respectively,The GFA and thermal stability of the Nd-Fe-Al-Y alloys were discussed.     

Cast bulk ZrTiAlCuNi amorphous alloys

Cylindrical bulk amorphous samples with diameters up to 10 mm have been prepared by casting ZrTiAlCuNi alloys in a copper mould. In order to rank glass-forming ability as a function of alloy composition, alloys were also cast into wedge-shaped moulds; to a first approximation, the thickness of the amorphous region obtained can be taken as an indication of glass-forming ability. The compositions which lead to the production of bulk glasses all have reduced glass transition temperatures in excess of 0.65 and the extremely high glass-forming ability of these compositions is discussed. We suggest that both the Al and Ti contents are determining factors for the production of bulk amorphous samples and these are believed to reduce the driving force for, and hence the rate of, crystallisation. These amorphous alloys have been found to display high thermal stability and can be annealed for several minutes in the supercooled liquid region. They are ductile at room temperature and have a high value of yield stress.     

Study of structural free volumes in the supercooled liquid state of bulk amorphous ZrTiCuNiBe

Structural free volumes in amorphous alloys play an important role for a lot of solid state properties. In this paper, we report on the determination of both the size and the chemical environment of structural free volumes in bulk amorphous Zr₄₁Ti₁₄Cu_12.5Ni₁₀Be_22.5 and particularly in the supercooled liquid state of the alloy by making use of measurements of the positron annihilation radiation. The free volumes in the supercooled liquid state are detected to be surrounded dominantly by Be and Ti atoms together with less Zr atom. The present investigations are of interest for atomic-scale understanding of the atomic processes in bulk amorphous alloys.     

Densification Behavior and Wear Response of Spark Plasma Sintered Iron‐Based Bulk Amorphous Alloys

In the present study, spark plasma sintering (SPS) process is used to sinter Fe‐based bulk amorphous alloys from starting amorphous powder. The sintering was performed in supercooled liquid region (at 630 °C with uniaxial pressure of 70 MPa) where plastic flow of the amorphous powder results in better densification without crystallization. To study the crystallization behavior and its influence on mechanical behavior, the sintered discs were de‐vitrified by annealing at 700 and 800 °C. Detailed characterization of phase development, microhardness at different loads, and wear behavior of the as‐sintered and annealed alloys is presented.     

Ti-based amorphous alloys with a wide supercooled liquid region

Ti-Cu-Ni-Co quaternary amorphous alloys produce by melt spinning were found to have a wide supercooled liquid region before crystallization, though no glass transition was observed in Ti-Cu binary amorphous alloys. The largest temperature interval of the supercooled liquid region (ΔT_x) is as large as 90 K for Ti₅₀Cu₂₅Ni₂₀Co₅.There is a tendency for ΔT_x to increase with an increase in storage modulus and with a decrease in loss modulus. It is therefore presumed that the increase in ΔT_x for the multicomponent amorphous alloy is due to the suppression of crystallization for the supercooled liquid resulting from the increase in viscosity.     

New features of the low temperature ductile shear failure observed in bulk amorphous alloys

Fractographic studies of ductile shear failure under the uniaxial compression for rod–like samples of the Zr_41.2Ti_13.8Ni₁₀Cu_12.5Be_22.5 and Cu₅₀Zr₃₅Ti₈Hf₅Ni₂ bulk amorphous alloys at temperatures 300 and 77 K are presented. The mechanisms of shear deformation and failure appeared to have characteristics in common with other amorphous alloys prepared in the form of thin ribbons. However, there were a number of new fractographic features observed due to the bulk character of the samples and to the large supercooled liquid region of these alloys.     

宽过冷液相区铁基非晶合金的形成和磁性

用熔体急冷法制备出具有明显的玻璃转变和较宽的过冷液相区的Fe-Co-(Nb)-Zr-B非晶合金,研究了热稳定性和软磁性能。结果表明,在Fe-Co-Zr-B四元合金中添加适量的Nb可以显著扩大过冷液相区,提高合金的热稳定性。当冷却速率降低时,急冷合金具有非晶和纳米晶的复相结构。非晶合金的饱和磁化强度随Nb含量的增加而减小。不同Nb含量的非晶合金的饱和磁致伸缩系数均较低。在低于晶化温度的温度下退火可以有效地降低矫顽力,改善软磁性能。晶化导致软磁性能降低。