微量元素对Cu-Zr-Al块体金属玻璃形成能力及力学性能的影响

研究微量元素Ag、Ti、Ga、Ni和Sn对Cu55Zr38Al7铜基块体金属玻璃形成能力及力学性能的影响。结果表明:添加2%(摩尔分数)的Ag、Ti或Ga均可以提高Cu55Zr38Al7合金的玻璃形成能力;用6%的Ag替代Cu,玻璃棒的临界直径可从2 mm增加到4 mm;因此,替代化学性质相似的元素或者扩大合金系的原子尺寸范围对提高玻璃形成能力具有显著的效果;然而,添加微量元素均不同程度地降低Cu-Zr-Al金属玻璃的硬度。断口表面形貌显示;微量相似元素替代影响基体在压缩过程中剪切带的繁殖;在微量元素替代的伪四元铜基块体金属玻璃中,2%Ti和2%Ag替代可分别获得最大压缩强度2 163 MPa和最大压缩应变8.7%。因此,通过添加微量元素可以调谐金属玻璃的玻璃形成能力和力学性能。     

Effects of Ce and Mm additions on the glass forming ability of Al–Ni–Si metallic glass alloys

The effects of Ce and Mm contents on the glass forming ability (GFA) of melt-quenched Al_89−xNi₈Ce_xSi₃ and Al_89−xNi₈Mm_xSi₃ (x = 0, 1, 3, 5, 7 at.%) alloys have been systematically investigated by X-ray diffraction (XRD) and differential scanning calorimetry (DSC). According to the XRD and DSC results, both Ce and Mm elements can enhance the GFA and thermal stability of the Al–Ni–Si alloys. Moreover, only the x = 5 and x = 7 alloys are totally amorphous in both systems quenched at the wheel speed of 36.6 m/s. Compared with amorphous Al₈₄Ni₈Ce₅Si₃ alloy at different cooling rates, amorphous Al₈₄Ni₈Mm₅Si₃ alloy has higher GFA which is considered to have relation to the different atomic structure of the amorphous alloy.     

Cu对Mg-Zn-Ca合金非晶形成能力与力学性能的影响

采用铜模造制备直径为3 mm的Mg70-xZn25Ca5Cux(x=1,2,3.5,5)系列合金.分别采用扫描电镜(SEM)、X射线衍射仪(XRO)、力学性能试验装置研究合金的显微组织、相组成和铸态样品的压缩性能,并对断日形貌进行分析.结果表明:Mg69Zn25Ca5Cu1可以形成直径为3 mm的非晶合金,其强度和塑性应变分别为690 MPa和1.7%.与Mg-Zn-Ca合金相比,其非晶形成能力和塑性应变均有提高.同时这也是目前在直径大于2 mm的Mg基非晶合金中所发现的最大塑性应变量.     

Formation and mechanical properties of bulk Cu-Ti-Zr-Ni metallic glasses with high glass forming ability

Bulk amorphous Cu52.5Ti30Zr11.5Ni6 and Cu53.1Ti31.4Zr9.5Ni6 alloys with a high glass forming ability can be quenched into single amorphous rods with a diameter of 5 mm, and exhibit a high fracture strength of 2 212 MPa and 2 184 MPa under compressive condition, respectively. The stress—strain curves show nearly 2% elastic strain limit, yet display no appreciable macroscopic plastic deformation prior to the catastrophic fracture due to highly localized shear bands. The present work shows clearly evidence of molten droplets besides well-developed vein patterns typical of bulk metallic glasses on the fracture surface, suggesting that localized melting induced by adiabatic heating may occur during the final failure event.     

Ti-Cu基合金玻璃形成能力与力学性能

本文基于“二元共晶混合”法设计Ti-Cu-Ni-Zr合金成分,通过水冷铜模铸造法制备出不同直径Ti-Cu-Ni-Zr合金棒。利用X射线衍射仪(XRD)、差示扫描量热仪(DSC)、万能试验机和扫描电镜(SEM)研究了Ti-Cu-Ni-Zr合金玻璃形成能力和力学性能。结果表明,Ti-Cu-Ni-Zr合金具有较高的玻璃形成能力,其临界直径可达4 mm;Ti-Cu-Ni-Zr合金玻璃形成能力近似相等,而表征玻璃形成能力的热力学参数过冷液相区ΔT_x,参数γ,约化玻璃转变温度T_rg也近似相等。通过对合金力学性能进行研究,结果表明,Ti_32.3Cu_47.6Ni_7.9Zr_12.2和Ti_31.6Cu_48.2Ni_7.7Zr_12.5大块非晶合金分别具有0.7%和0.2%的塑性,而Ti₃₀Cu_49.5Ni_7.2Zr_13.3和Ti_28.55Cu_50.7Ni_6.75Zr₁₄大块非晶合金断裂机制近似为脆性断裂。Ti-Cu-Ni-Zr大块非晶合金塑性越大,其剪切带数量越多且扩展深度越大,反之亦然。另外,对于塑性材料,当锯齿流变振幅越大时,对应样品表面剪切带扩展深度越明显,当锯齿流变振幅越小时,对应样品表面剪切带扩展深度较浅;近似脆性断裂的锯齿流变对应次剪切带萌生,而对于完全脆性大块非晶合金,在应力-应变曲线上并未发现锯齿流变现象,相应的在样品外表面也并未发现次剪切带。     

Ni对Mg-Cu-Tb非晶合金形成及力学性能的影响

利用熔体铜模喷铸法制备出直径为3 mm的Mg65Cu25-xNixTb10(x=0,5,10)非晶合金。利用X射线衍射、差热分析、压缩实验分析和扫描电镜分析了添加Ni元素对Mg-Cu-Tb非晶合金形成能力及力学性能的影响。研究表明:随着Ni含量的增加,合金的玻璃转变温度Tg增大;开始结晶温度Tx降低;过冷液相区宽度ΔTx减小,约化玻璃转变温度Trg从0.562降至0.530,非晶形成能力逐渐降低。压缩实验结果表明:当Ni含量增加到5%时可以明显提高Mg-Cu-Tb-Ni非晶合金的断裂强度。     

Effects of alloy addition on the improvement of glass forming ability and plasticity of Mg–Cu–Tb bulk metallic glass

The effects of alloy addition on the glass forming ability, thermal stability and mechanical properties of Mg–Cu–Tb-based bulk metallic glasses were investigated. It was found that appropriate additions of Ag, Zn or Be in Mg₆₅Cu₂₅Tb₁₀ could not only improve the glass forming ability, but also enhance the strength and plasticity of these amorphous metallic alloys within a certain composition range.     

Design of Bulk metallic glasses with high glass forming ability and enhancement of plasticity in metallic glass matrix composites: A review

To overcome some of the limits of existing metallic alloys, a new alloy design concept has been introduced recently in order to control the crystallinity, i.e. to utilize crystalline, quasicrystalline, and amorphous structures. In particular, bulk metallic glasses (BMGs) receive great attention because of their unique properties due to their different atomic configuration. Recently, significant progress in enhancing glass forming ability (GFA) has led to the fabrication of BMGs having potential for application as structural and functional materials. Moreover, successful design of BMG matrix composite microstructure suggests that the plasticity of BMGs can be controlled properly. In this review article, we introduce recent research results on the design of BMGs with high GFA and on the enhancement of plasticity in metallic glass matrix composites.     

Mechanical properties of Pd–Cu–Si bulk metallic glass

In present work, Pd_77.5Cu₆Si_16.5 bulk metallic glass balls with diameter up to 6 mm have been prepared by fluxing and water quenching method. It has been found that the Pd–Cu–Si glassy alloy exhibits a compressive plastic strain of about 11.4%, together with strain hardening characteristics. A large localized shear band, accompanied by a shear step of about 220 μm in size, has been clearly observed on the deformed specimen. The related shear plane is estimated to have an angle of 42 degrees with respect to the loading axis. The good ductility of the glassy alloy is believed to be partially attributed to strain hardening and the higher resistance of the glassy alloy to crack nucleation and propagation due to its large Poisson's ratio.     

Effect of Si, Pd and La additions on glass forming ability and thermal stability of Zr-Ni-based amorphous alloys

In the present paper, the influence of minor additions of Si, Pd and La with representative atomic sizes on glass forming ability (GFA) and thermal stability of Zr-Ni-based amorphous alloys has been investigated using X-ray diffraction (XRD), differential scanning calorimetry (DSC), transmission electron microscopy (TEM) and high resolution TEM (HRTEM). The results show that minor additions of La, Pd and Si can improve GFA of Zr-Ni-based alloys and La exhibits the optimum effect on enhancing GFA. The efficient cluster packing model can well explain the correlation between atomic sizes of additional elements and GFA of amorphous alloys. In addition, the relationship of the atomic size between the additional element and Zr has a more important effect on GFA than that between the additional element and Ni. The activation energy for crystallization of the Zr-Ni-based amorphous alloys with Si, Pd and La additions is obviously higher than that of the Zr_66.7Ni_33.3 amorphous alloy, and increases with decreasing distance between neighboring atoms. The thermal stability has a relation with topological short-range ordering of amorphous alloys. The proper addition of small atoms is preferential to enhance thermal stability of amorphous alloys due to stronger short-range ordering. Moreover, the small or intermediate atom addition can produce even better effect on thermal stability than the large atom addition.     

Si和Cu元素对铝-镀锌钢GTAW接头性能的影响

通过填加4种不同的焊丝,在焊缝中加入不同含量的Si,Cu元素,进行了5A02铝合金和镀锌钢板之间异种金属的钨极氩弧焊(GTAW)搭接试验.试验发现Cu元素含量高于一定值时,金属间化合物层厚度大于10μm,而当Cu元素含量较低时,随着Si元素加入量的增加,金属间化合物层的厚度减小,最小约为2μm.当Si元素含量大于5%时,抗拉强度接近136 MPa.但此时,制约焊缝性能的主要因素是焊缝根部出现的气孔聚集缺陷.另外,Si元素的加入还可以改善焊缝与铝合金母材连接处柱状晶区的组织.     

Thermodynamic model for glass forming ability of ternary metallic glass systems

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Microstructure and mechanical properties of metallic glass/metallic glass composites

We report microstructure and mechanical properties of bulk metallic glass (BMG)/metallic glass composites fabricated by mechanical alloying with subsequent consolidation process. The microstructural investigations of a bulk composite reveal that a submicron-scale layered structure with irregular interfaces consists of three amorphous phases in tornado-like morphology. Based on these results, poor plasticity of the metallic glass composite can be understood possibly due to the irregular interfacial morphology of the submicron-scale heterogeneous amorphous phases throughout the materials.     

Effect of minor Nb addition on mechanical properties of in-situ Cu-based bulk metallic glass composite

In-situ formed (Cu_0.6Zr_0.3Ti_0.1)₉₅Nb₅ bulk metallic glass (BMG) composite with Nb-rich dendrite randomly dispersed in hard glassy matrix was prepared by casting into a water-cooled copper mold. The dendrite has much smaller hardness and elastic modulus than glassy matrix, and the stress concentration at interface provides a channel for the initiating and branching of shear bands upon loading, thus leading to a high compressive fracture strain of 6.08% and fracture strength about 2200 MPa. Comparing with other Cu-based BMG composite, the fracture strength of present (Cu_0.6Zr_0.3Ti_0.1)₉₅Nb₅ composite is not significantly reduced, indicating that the addition of Nb in the current work is an effective and effortless way to fabricate new practical BMG composites with enhanced strength and good plasticity.     

添加微量Fe对Zr_(55)Al_(10)Ni_5Cu_(30)块体金属玻璃非晶形成能力和力学性能的影响(英文)

通过磁悬浮熔炼和铜模吸铸法制备直径3mm的(Zr0.55Al0.10Ni0.05Cu0.30)100-xFex(x=0,1,2,3,4)合金试样,研究Fe元素的微量添加对Zr55Al10Ni5Cu30块体金属玻璃非晶形成能力和力学性能的影响。研究表明,合理添加Fe元素(不超过3%,摩尔分数)导致约化玻璃转变温度Trg(=Tg/Tl)和参数γ(=Tx/(Tg+Tl))增大,因而其非晶形成能力增大,但添加过量的Fe元素(4%)会导致其非晶形成能力的降低。添加Fe元素也会显著地改善Zr55Al10Ni5Cu30块体金属玻璃的压缩塑性及提高其压缩断裂强度,当Fe元素的添加量为2%时,直径3mm、长度6mm的试样在压缩时出现一定的塑性及加工硬化现象。Fe元素添加量为4%形成的金属玻璃基复合材料,同样也显示良好的压缩塑性和高的压缩断裂强度。     

不锈钢网增强锆基非晶复合材料的压铸制备及力学性能研究

全程真空压铸技术的快速发展为大块非晶合金的工业化应用提供了可能,受到了广泛关注。但是,非晶合金的室温脆性限制了压铸结构件在一些关键领域的应用。本论文利用压铸工艺高速充型及高压凝固的特性,通过在Vit1锆基非晶合金中引入304不锈钢网叠层焊接制造的骨架,成功制备出了不同体积分数晶态相增强的非晶复合材料,并系统研究了不锈钢网体积分数对力学性能的影响。研究结果表明,不锈钢网在非晶基体中均匀分布,与非晶合金存在冶金界面结合。力学性能测试显示,随着不锈钢编织网的引入,室温脆性的压铸Vit1块体金属玻璃的塑性得到了显著提升。随着不锈钢网目数增大(对应晶态相体积分数增大),非晶复合材料的塑性呈增大的趋势,但是,当目数超过200时,过细的孔洞会导致骨架局部区域无法填充,恶化性能。当晶态相的体积分数为53.7％时,断裂应变达到最大值,约为10％左右,其值高于传统不锈钢纤维增韧的Zr基非晶复合材料。韧化机制分析表明,压铸非晶合金出现脆-延性转变的根本原因是不锈钢网对剪切带扩展进行高效抑制,促进剪切带的增殖和萌生,减少宏观塑性变形的局域化。本研究为非晶复合材料的结构设计提供了新的思路,对于促进非晶合金的更广泛应用具有重要的工程价值。     

Effect of carbon addition on microstructure and mechanical properties of Ti-based bulk metallic glass forming alloys

A kind of novel Ti-based composites was developed by introducing different amounts of carbon element to the Ti50 Cu23 Ni20 Sn7 bulk metallic glass forming alloys. The thermal stability and microstructural evolution of the composites were investigated. Room temperature compression tests reveal that the composite samples with 1% and 3% （mass fraction） carbon additions have higher fracture strength and obvious plastic strain of 2 195 MPa, 3. 1% and 1 913 MPa, 1.3% respectively, compared with those of the corresponding carbon-free Ti50 Ni20 Cu23 Sn7 alloys. The deformation mechanisms of the composites with improved mechanical properties were also discussed.     

In-situ synthesis and mechanical properties of Zr-based bulk metallic glass matrix composites manipulated by nitrogen additions

Our study investigates in-situ synthesis and mechanical properties of Zr-based bulk metallic glass (BMG) matrix composites via arc plasma-induced accelerated displacement reaction (APADR) process. The aluminum nitride precursor under arc plasma-induced ultra-high temperature results in higher contents of dissolved nitrogen as well as precipitation of zirconium nitride (ZrN) particles in a Zr-based amorphous matrix. The nitrogen in the matrix results in a decrease of crystallization resistance (lower T_x and reduced glass-forming ability), but an increase of mechanical stability (a decrease of strain burst sizes). In particular, in-situ formed ZrN, which exhibits a homogeneous distribution and strong interfacial bonding with the matrix, causes an increase in compressive fracture strength and significant plastic deformation in the composite compared with the monolithic BMG. The formation of multiple shear bands and the enhancement of shear band interactions by the dissolved nitrogen as well as the in-situ formed ZrN particles were carefully confirmed by a statistical analysis on serrated flows. These results give us a guideline on how to manipulate nitrogen contents and fabricate in-situ BMG matrix composites with improved mechanical properties via APADR process.     

Cu50 Zr42 Al8块体金属玻璃的组织和力学性能

采用悬浮熔炼-铜模吸铸法制备了Cu50Zr42Al8块体金属玻璃,研究了其楔形试样的组织演变.随着熔体凝固过程中冷却速度的变化,楔形试样中存在表面全非晶区,中心晶体区以及二者之间的过渡区域,并确定Cu50Zr42Al8块体金属玻璃临界尺寸为4.8 mm.分别考察了φ4 mm铸态完全非晶棒和φ5 mm非晶复合棒的力学性能.φ4 mm非晶棒的压缩断裂强度,弹性应变和塑性应变分别为2260 MPa,2.0%,0.4%,几乎没有塑性变形.而φ5 mm铸态非晶复合棒的屈服强度、断裂强度分别为1670MPa、1849 MPa,弹性应变和塑性应变分别为1.6%和1.9%.非晶基体中存在的马氏体相CuZr和正交晶相Cu10Zr7的竞争影响了非晶复合棒的最终力学行为.     

Zr56.6Cu17.3Ni12.5Al9.6Ti4块体非晶合金的玻璃形成能力

采用低纯度的原料,通过电弧熔炼铜模铸造法制备了直径达10mm的Zr56.6Cu17.3Ni12.5Al9.6Ti4非晶合金圆棒.该合金玻璃转变温度tg＝385.8℃,晶化温度tx＝464.2℃,过冷液相区温差Δtx＝78.4℃,约化玻璃温度trg(tg/tmL)＝0.62.以基于DTA的合金凝固点偏移的方法确定该合金的临界冷却速度Rc=7.1℃/s,低于商业合金Vit.105合金的临界冷速(约为10℃/s).楔形试样对比结果显示:Zr56.6合金试样中的非晶组织区域明显大于Vit.105合金的,预示前者具有较好的实际玻璃形成能力.以上结果表明,Zr56.6Cu17.3Ni12.5Al9.6Ti4合金是Zr-Al-Ni-Cu-Ti系中玻璃形成能力最强的合金之一.