最新录用 | 当期目录 | 过刊浏览 | 热点文章 | 虚拟专辑 | 阅读排行 | 下载排行 | 引用排行 | 期刊订阅

金属学报, 2025, 61(6): 900-908 DOI: 10.11900/0412.1961.2023.00299

研究论文

Zr61Ti2Cu25Al12 非晶合金的过冷液体特性与晶化解耦

李晓诚,1, 寇生中,1,2, 李春玲3, 李春燕1,2, 赵燕春1,2

1 兰州理工大学 材料科学与工程学院 兰州 730050

2 兰州理工大学 省部共建有色金属先进加工与再利用国家重点实验室 兰州 730050

3 兰州理工大学 机电工程学院 兰州 730050

Supercooled Liquid Characteristics and Crystallization Decoupling of Zr61Ti2Cu25Al12 Amorphous Alloy

LI Xiaocheng,1, KOU Shengzhong,1,2, LI Chunling3, LI Chunyan1,2, ZHAO Yanchun1,2

1 School of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou 730050, China

2 State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals, Lanzhou University of Technology, Lanzhou 730050, China

3 School of Mechanical and Electrical Engineering, Lanzhou University of Technology, Lanzhou 730050, China

通讯作者: 李晓诚，lixc@lut.edu.cn，主要从事非晶合金方面的研究；寇生中，kousz@lut.cn，主要从事非晶合金方面的研究

责任编辑: 梁烨

收稿日期: 2023-07-11   修回日期: 2023-10-11  

基金资助: 国家自然科学基金项目(51971103)
国家自然科学基金项目(51861021)
甘肃省重点研发计划项目(20YF8GA052)

Corresponding authors: LI Xiaocheng, Tel:(0931)2976702, E-mail:lixc@lut.edu.cnKOU Shengzhong, professor, Tel: (0931)2976702, E-mail:kousz@lut.cn

Received: 2023-07-11   Revised: 2023-10-11  

Fund supported: National Natural Science Foundation of China(51971103)
National Natural Science Foundation of China(51861021)
Key Research and Development Program of Gansu Province(20YF8GA052)

作者简介 About authors

李晓诚，男，1983年生，博士

摘要

为了更深入地了解非晶合金过冷液体的特性和晶化行为，本工作针对具有高断裂韧性和良好生物相容性并在柔顺机构和生物植入体方面具有应用前景的Zr61Ti2Cu25Al12非晶合金，采用快速扫描量热和常规热分析技术相结合，实现了6个数量级(10-2~104 K/s)升温速率的调控，揭示出超宽温度范围内过冷液体依赖于升温速率的动力学特性：过冷液体的动力学行为滞后于温度的快速变化，2者符合VFT方程；脆度系数的小幅变化(m = 35~47)意味着其过冷液体结构随温度变化比较平缓，从而表现出具有一定的“强”液体行为；通过平移时间维度坐标，得出从玻璃转变到熔点整个温度范围内的平均m ≈ 45。该非晶合金晶化过程中晶体生长的温度依赖性表明生长激活能随温度升高逐渐降低，单位温度下的激活能降约为0.5 kJ/(mol·K)，在玻璃转变温度附近，晶体生长动力学与黏性流动间发生解耦，通过引入解耦指数(ξ = 0.84)使得晶体生长动力学系数(Ukin)与黏度(η)在更宽的温度范围内符合幂律关系：Ukin ∝ η-ξ。

关键词： 非晶合金; 快速扫描量热; 过冷液体; 黏度; 脆度; 晶化

Abstract

Plastic deformation of amorphous alloys below the glass transition temperature is inhomogeneous and highly localized within narrow shear bands. However, the processing and manufacturing of amorphous alloys in their supercooled liquid state exhibit unique advantages for engineering application. Although the discovery of bulk metallic glasses has substantially expanded the processing time and temperature window, experimental research on the supercooled liquid states of amorphous alloys remains widely limited to narrow regions near either their glass transition temperature or melting point. The crystallization of supercooled liquids severely limits the characterization of their kinetic behavior in the high-temperature region. Therefore, an enhanced comprehensive understanding of supercooled liquid characteristics and crystallization kinetic behavior of metallic glasses is necessary. Zr61Ti2Cu25Al12 amorphous alloy shows broad application prospects in the fabrication of flexible mechanism components and biological implants because of its high fracture toughness, high elastic strain limit, and good biocompatibility properties. Six orders of magnitude (10-2-104 K/s) of heating rate changes were achieved for Zr61Ti2Cu25Al12 metallic glass by combining flash differential scanning calorimetry (FDSC) with conventional DSC. This implies that the kinetic characteristics of the alloy supercooled liquid is dependent on the heating rate of the alloy over an ultra-extensive temperature range. The kinetic behavior of the alloy supercooled liquid lags behind the rapid changes in temperature, and both follow the Vogel-Fulcher-Tammann equation. The small variation in the fragility index (m = 35-47) indicates that the supercooled liquid structure changes gently with temperature, thereby showing a “strong” liquid behavior. An average m ≈ 45 is obtained over the entire temperature range from the glass transition temperature to the melting point via time dimension coordinate translation. The dependence of crystal growth on temperature during the crystallization process of the Zr61Ti2Cu25Al12 amorphous alloy indicates that the activation energy of crystal growth gradually decreases with increasing temperature, and the reduction in activation energy per unit temperature obtained here is approximately 0.5 kJ/(mol·K). Near the glass transition temperature, decoupling occurs between crystal growth kinetics and viscous flow. The kinetics coefficient for crystal growth (Ukin) follows a power law relationship with viscosity (η) over a wide temperature range when an exponent ξ = 0.84 is introduced: Ukin ∝ η-ξ.

Keywords： amorphous alloy; flash DSC; supercooled liquid; viscosity; fragility; crystallization

PDF (1611KB) 元数据 多维度评价 相关文章 导出 EndNote| Ris| Bibtex  收藏本文

本文引用格式

李晓诚, 寇生中, 李春玲, 李春燕, 赵燕春. Zr61Ti2Cu25Al12 非晶合金的过冷液体特性与晶化解耦[J]. 金属学报, 2025, 61(6): 900-908 DOI:10.11900/0412.1961.2023.00299

LI Xiaocheng, KOU Shengzhong, LI Chunling, LI Chunyan, ZHAO Yanchun. Supercooled Liquid Characteristics and Crystallization Decoupling of Zr61Ti2Cu25Al12 Amorphous Alloy[J]. Acta Metallurgica Sinica, 2025, 61(6): 900-908 DOI:10.11900/0412.1961.2023.00299

非晶合金(又称金属玻璃)属于非晶态物质范畴，不同于晶体结构可由230个空间群对称性严格定义，其内部原子排列为近程有序而远程无序，不具有平移对称性，因此，不存在诸如位错、晶界等晶体缺陷，从而展现出一些优异的力学、物理和化学性能等[1~6]。Zr61Ti2Cu25Al12 (原子分数，%，下同)非晶合金自被发现以来[7]，科研人员[8~10]对其力学和生物相容性进行了深入研究，该合金具有高断裂韧性和高疲劳强度，有潜力成为柔顺机构和生物植入体的新一代材料。最近，刘帅帅等[11]在过冷液态下对该合金施加塑性变形，研究了其流变行为，发现受温度和变形速率的影响，该合金在过冷液态的变形包含3种模式。

Kissinger方法[12]广泛应用于研究玻璃的晶化动力学行为[13,14]，通过绘制升温速率(Φh)与特征温度(Tc)之间的关系曲线，即ln(Φh / Tc2)-1 / Tc，由曲线斜率求得晶化激活能。常规差示扫描量热仪(DSC)的Φh (< 10 K/s)范围较窄，Kissinger图通常表现为直线，表明晶化过程具有单一的激活能，如果将Φh扩展至更宽范围(如达到104 K/s数量级)，那么Tc与Φh之间的依赖关系有待于进一步研究。最近，杨群等[15,16]利用快速扫描量热(FDSC)技术对Ni80P20合金和铝基非晶合金的玻璃转变和过冷液体性质进行了表征。Orava等[17]研究了相变材料Ge2Sb2Te5 (GST)在宽Φh范围内的过冷液体行为和晶化动力学。综上，FDSC的应用为在宽温度范围内揭示过冷液体性质和晶体生长动力学提供了工具[18]。根据Angell[19]所述，在玻璃转变温度(Tg)以上，强液体表现出接近Arrhenius关系的行为，而脆性液体表现出偏离Arrhenius关系的行为，具体体现为黏性流动激活能的变化。对于脆性液体而言，该激活能在Tg附近很高，随着温度的升高显著降低。液体中原子迁移与温度间的依赖性可由黏度(η)表征，高温时，η和扩散系数(D)遵守Stokes-Einstein[1]关系：ηD = kBT (式中，kB为Boltzmann常数，T为热力学温度)，即η和D是耦合的。但是在一些金属[20]、有机物[21]和氧化物[22,23]玻璃形成体中，当温度降至Tg附近时，这种关系不再适用，即晶体生长动力学与黏性流动之间发生解耦(或去耦合)。对于Zr61Ti2Cu25Al12非晶合金，其解耦情况有待于进一步研究。

基于此，本工作利用FDSC将Φh提高至104 K/s数量级，研究Zr61Ti2Cu25Al12非晶合金在超宽温度范围内过冷液体的动力学行为和晶化过程中晶体生长动力学与黏性流动之间的依赖关系。以期为非晶合金过冷液体和晶化动力学研究提供理论依据，为Zr61Ti2Cu25Al12非晶合金的制备和加工，尤其是过冷液态下的塑性成形提供技术指导。

1 实验方法

以纯度均大于99.95% (质量分数)的Zr、Ti、Cu和Al为原料，按照名义成分为Zr61Ti2Cu25Al12配料60 g，采用水冷铜坩埚感应悬浮熔炼炉在高纯Ar气(99.999%，体积分数)保护下反复翻转熔炼母合金3次以上以保证成分均匀，随后通过铜模吸铸成直径为3 mm的棒状试样。非晶合金条带制备是在高纯Ar气保护下通过感应加热放置于带喷嘴石英管中的破碎合金锭，待熔化后将高温熔体喷射到高速旋转的铜辊表面，其线速度约为60 m/s，最终获得的带材尺寸约为0.5 mm (宽) × 0.02 mm (厚)。采用D8 ADVANCE X射线衍射仪(XRD，CuKα，波长λ = 0.154 nm)表征样品结构，衍射角2θ = 20°~80°，扫描速率为4°/min。采用JEM-F200高分辨透射电子显微镜(HRTEM)进行微观结构表征，样品通过电解双喷制备，电解液为液氮保护下的10%HClO4 + 90%C2H5OH (体积分数)溶液，工作电压和电流分别为22 V和30~40 mA。采用Mettler Toledo Flash DSC 2 + FDSC和Netzsch STA 449F3常规DSC对合金进行热分析，连续Φh分别为100~5.5 × 104 K/s和0.05~1.33 K/s。FDSC配置XENF20_65299传感器芯片，允许温度上限1273 K，极限升降温速率分别为6 × 104和-4 × 104 K/s，制冷器型号为Huber TC100。实验前采用标准试样In (99.999%，质量分数)对传感器芯片温度和热量值进行校准[24,25]，测试过程中保护气体N2 (99.99%，体积分数)的流速为50 mL/min，传感器支架温度为173 K。FDSC样品制备是在仪器自带的光学显微镜下将非晶薄带切成小于芯片面积的合适尺寸，对应质量小于1 μg，其值可通过熔化焓(ΔHm)相等来确定。对FDSC熔化峰面积积分得ΔHm为0.066 mJ，通过常规DSC在Φh = 0.33 K/s时测试的比熔化焓为106 J/g，2者熔化焓相等即可计算出FDSC样品质量为：0.066 × 10-3 J / (106 J/g) = 6.2 × 10-7 g。常规DSC样品制备是通过金刚石切片机从棒状试样上切制而成，质量约20 mg，实验中采用Al2O3坩埚，保护气体N2流速为50 mL/min。

2 实验结果

图1a和b分别为铸态Zr61Ti2Cu25Al12非晶合金的XRD谱和HRTEM像，图1b插图为对应的选区电子衍射(SAED)花样。可以看出，由于组成原子在实空间内没有长程平移对称性，因而Fourier变换后的倒空间内不再表现出具有周期性的斑点或条纹，致使XRD谱和SAED花样分别表现为漫散射峰和弥散的晕环，HRTEM像也呈现出Zr61Ti2Cu25Al12非晶合金组成原子完全无序分布的非晶态结构。

图1

新窗口打开| 下载原图ZIP| 生成PPT

图1   直径为3 mm Zr61Ti2Cu25Al12合金铸态棒的XRD谱和HRTEM像

Fig.1   XRD spectrum (a) and HRTEM image (Inset shows selected area electron diffraction (SAED) pattern) (b) of Zr61Ti2Cu25Al12 as-cast rod with a diameter of 3 mm


图2a和b分别为Zr61Ti2Cu25Al12非晶合金的常规DSC和FDSC热流曲线，作为对比图2a中也包含了500 K/s的曲线。从图2a可以看出，常规DSC连续升温过程中，玻璃化转变和晶化过程所表现出的动力学特性体现为2个方面：(1) Tg、晶化开始温度(Tx)、晶化峰值温度(Tp)和过冷液相区宽度ΔTx (= Tx - Tg)随Φh增大而增大；(2) 低Φh阶段的两步晶化逐渐演变为高Φh阶段的同步晶化，具体表现为： Φh从0.05 K/s升高到0.17 K/s过程中，热流曲线呈现出2个完全独立的晶化放热峰，当Φh = 0.33 K/s时，第一步晶化还未结束而第二步晶化过程已经开始，随着Φh达到0.67 K/s，两步晶化过程完全合并为单一的晶化峰。

图2

新窗口打开| 下载原图ZIP| 生成PPT

图2   Zr61Ti2Cu25Al12合金的常规差示扫描量热(DSC)和快速扫描量热(FDSC)热流曲线

Fig.2   Heat flow curves of conventional DSC at low heating rate (Φh) from 0.05 K/s to 1.33 K/s (As a comparison, 500 K/s is also included in Fig.2a) (a) and FDSC at high Φh from 100 K/s to 5.5 × 104 K/s (Φh = 100, 200, 400, 600, 800, 1000, 1500, 2000, 2500, 3000, 3500, 4000, 4500, 5000, 6000, 7000, 8000, 9000, 10000, 15000, 20000, 25000, 30000, 35000, 40000, 45000, 50000, 55000 K/s) (b) for Zr61Ti2Cu25Al12 metallic glass (DSC—differential scanning calorimetry, FDSC—fast differential scanning calorimetry, Φc─cooling rate, T─temperature, Tg─glass transition temperature, Tx─crystallization temperature, Tp─crystallization peak temperature, ΔHm─melting enthalpy)


图2b的FDSC降温速率Φc = -4 × 104 K/s，降温过程热流曲线未显示出晶化放热峰，随后以不同Φh循环扫描。随着Φh从100 K/s到5.5 × 104 K/s逐渐增大，与常规DSC相似，特征温度也随之向高温方向移动，Φh越大，这种偏移幅度越不明显，表明高Φh阶段较低Φh阶段动力学效应不明显。另外，相比于Tx和Tp，Tg随Φh增加较缓，这使得ΔTx随Φh增大而增大，表现出明显的动力学特征。

3 分析讨论

3.1 过冷液体的动力学行为

图3为Zr61Ti2Cu25Al12非晶合金玻璃化转变激活能和晶化激活能随温度的变化及对应的Kissinger图。ln(Φh / T2)-1000 / T之间的关系通过Kissinger方程[12]来描述：

ln(Φh / T2)=-E / (RT)+Const

式中，E为激活能，R为理想气体常数，Const为常数。由于常规DSC的连续升温速率有限，Kissinger曲线通常表现为线性[26]，曲线斜率(-E / R)所表示的黏性流动或晶化激活能为定值，分别约为450和245 kJ/mol，如图3常规DSC所示。FDSC是常规DSC在高温范围的扩展，在常规DSC所测速率范围之外，曲线出现了明显的外凸弯曲，激活能逐渐降低，具体数据为：对于Tg，玻璃化转变激活能从Eg = 450 kJ/mol降至Eg / 2 (对应温度为770 K)历经的温度范围为94 K，得出单位温度下的激活能降为2.4 kJ/(mol·K)，即温度每升高1 K激活能约降为2.4 kJ/mol；对于Tp，激活能降至初始值一半(对应温度为1000 K)历经的温度范围为234 K，得出单位温度下的激活能降为0.5 kJ/(mol·K)。由此可知，抑制黏性流动或晶化的能垒随温度升高逐渐降低，意味着黏性流动或晶化阻力减小，过冷液体结构更容易发生变化，从而更趋向于脆性液体。相比于晶化激活能，玻璃化转变的黏性流动激活能对温度变化更加敏感，随温度升高其值下降更剧烈，“脆性”行为表现更明显。

图3

新窗口打开| 下载原图ZIP| 生成PPT

图3   Zr61Ti2Cu25Al12合金玻璃化转变激活能(Eg)和晶化激活能(Ep)及对应的Kissinger图

Fig.3   Changes in activation energy for glass transition (a) and crystallization (b) of Zr61Ti2Cu25Al12 amorphous alloy and corresponding Kissinger plots (E─activation energy, Eg─activation energy relative to Tg, Ep─activation energy relative to Tp)


图4a为Zr61Ti2Cu25Al12合金特征温度与Φh之间的依赖关系。有限温度范围的常规DSC显示特征温度与lnΦh之间符合Lasocka方程[27]所描述的线性关系：

图4

新窗口打开| 下载原图ZIP| 生成PPT

图4   Zr61Ti2Cu25Al12合金特征温度与升温速率(Φh)之间的关系及经时间维度调整后的曲线

Fig.4   Dependence of the characteristic temperatures in Zr61Ti2Cu25Al12 alloy on the natural logarithm of the Φh (a) and adjusted with proper time dimension shift (b) (m─fragility index; mTg─fragility relative to Tg; mTX─fragility relative to Tx; mTP─fragility relative to Tp; r2─determination coefficient; 4 denotes the relative scale on the y-axis, the same below)


T=a+blnΦh

式中，a和b为常数。随Φh增大，过冷液体的动力学行为滞后于温度的快速变化，当Φh扩展到FDSC所测速率范围时，这种线性关系将不再适用，更符合Vogel-Fulcher-Tammann (VFT)方程[28~30]：

lnΦh=B0-D0T0 / (T-T0)

式中，B0、D0和T0为拟合参数，D0和T0为影响曲线曲率的参数，B0为与时间维度相关影响曲线沿Φh轴平移的参数，具体数值见表1。可以看出，Φh在6个数量级(10-2~104 K/s)变化过程中所呈现的更高、更宽温度范围内，VFT方程可以很好地描述特征温度与Φh之间的依赖关系，拟合曲线决定系数(r2)均在0.99以上。进一步，通过Angell图中长弛豫时间端曲线斜率得到过冷液体的脆度系数(m)，其与 式(3)拟合参数D0和T0之间的关系为[31]：

表1   Zr61Ti2Cu25Al12合金特征温度的lnΦh-T拟合参数及决定系数(r2)

Table 1  lnΦh-T fitting parameters (B0, D0, T0) and r2 for characteristic temperatures of Zr61Ti2Cu25Al12 alloy

Characteristic temperatureB0D0

T0

K

r2
Tg23.57.2509.80.992
Tx19.012.5446.90.997
Tp17.911.7451.90.998

新窗口打开| 下载CSV


m=D0T0Tg / [(Tg-T0)2ln10]

将各特征温度对应的拟合参数分别代入即可得出过冷液体的m分别为：mTg = 47，mTx = 36和mTp = 35，如图4a所示。结果表明，由不同特征温度得出的m不尽相同。其中，Tx和Tp相差较小，并且2者随Φh变化趋势一致(图2b)，因此所得m近似相等，约为35。相比于Tx和Tp随Φh增大其值变化较大，Tg随Φh变化相对缓慢(图2b)，如：在整个Φh范围内(Φh = 5 × 10-2~5.5 × 104 K/s)，Tp从702 K升高至1205 K，变化幅度达503 K；而Tg从650 K升高至815 K，变化幅度仅为165 K，从而得到较大的m (47)，即Tg处窄的温度范围内(650~815 K)液体的结构变化略大于Tp处宽温度范围内(702~1205 K)液体的结构变化，液体的脆度也较大，这与前文得出的低温区(Tg附近)相比于高温区(Tp附近)表现出更脆的液体行为相一致。从更宽的温度范围来看，Zr61Ti2Cu25Al12非晶合金过冷液体低温区和高温区的m相差10左右，与钯基(为13)[32]相近，相比于铂基(为20)[32]，其值变化相对较小，说明该合金在过冷液态表现出弛豫时间或黏度随温度的平缓变化，其过冷液体结构不易发生显著变化，具有抵抗过冷液体结构“坍塌”的能力，从而表现出一定的“强”液体行为，类似于SiO2和GeO2等网状氧化物。

图4b为特征温度与lnΦh关系曲线沿纵轴适当平移调整后的VFT方程拟合结果。可以看出，经平移后的各特征温度与lnΦh关系仍符合VFT方程，拟合后的r2较高，为0.983，从而计算得出过冷液体的m ≈ 45。需要特别说明的是，这种将特征温度与lnΦh关系曲线沿时间维度轴平移的思路是将玻璃化转变和晶化这2个过程合并为单一的转变过程[33]，从而使用单一的VFT方程拟合，得出过冷液体的m，该m可以认为是在较宽温度范围内过冷液体脆度的平均值。另外，沿Φh轴平移的时间常数只是用以调整特征温度与lnΦh关系曲线，并没有绝对值意义，所以图4b中Φh轴未显示绝对刻度。

3.2 晶体生长动力学与黏性流动间的解耦

图5a为Zr61Ti2Cu25Al12非晶合金的Tg、Tx和Tp在常规DSC和FDSC Φh范围内的Kissinger图。Kelton[26]认为采用Kissinger方法研究玻璃晶化时，所得激活能在物理上为晶体生长所需能量，因为在玻璃化转变附近的低温深过冷区已经发生了预先形核，该温区属生长控制的晶化机制。在3.1节中，已对曲线斜率所代表的激活能随温度升高逐渐降低做出讨论，在此不再赘述。本节将对Zr61Ti2Cu25Al12非晶合金晶化过程中晶体生长的温度依赖性进行讨论。假定该非晶合金晶化方式为生长控制的连续长大，根据Ediger等[22]给出的关系：

图5

新窗口打开| 下载原图ZIP| 生成PPT

图5   Zr61Ti2Cu25Al12合金特征温度的Kissinger图及经时间维度调整后的曲线

Fig.5   Kissinger plots for characteristic temperatures of Zr61Ti2Cu25Al12 metallic glass (a) and adjusted with proper time dimension shift (b) (U─crystal growth rate; η─viscosity; Ukin─kinetic coefficient for crystal growth; Tc─characteristic temperatures Tg, Tx, and Tp)


U=Ukin{1-exp[-ΔG / (RT)]}

式中，U为晶体生长速率；ΔG为晶态和液态间的Gibbs自由能差，可以通过ΔHm与液相线温度(Tl)近似求得：ΔG = ΔHm (Tl - T) / Tl；Ukin为晶体生长的动力学系数，其值为ΔG无限大时U的极限值，可通过Ukin-η-1关系与η相联系，这与晶体生长过程中D与η符合Stokes-Einstein关系相类似。Cohen和Grest[34]应用自由体积模型和逾渗理论描述玻璃转变过程时给出了η的广义方程：

lgη=Ac+2Bc /{T-T1+[(T-T1)2+4CT]1/2}

根据η与Ukin在高温时反相关可得：

lgUkin=A-2B /{T-T1+[(T-T1)2+4CT]1/2}

式中，Ac和A为无量纲参数，Bc、B、C和T1为温度量纲参数。

图5a中实线为通过 式(5)所得的Zr61Ti2Cu25Al12非晶合金晶化过程中晶体生长的温度依赖关系(lnU-1000 / T)，其中，作为晶化过程的先导——代表黏性流动的Tg也包括在内，拟合参数具体数值见表2中的lnU-1000 / T。另外，η与T的依赖关系可以用VFT方程描述[28~30,35]：

表2   Zr61Ti2Cu25Al12合金特征温度的lnU-1000 / T和lnUkin-1000 / T拟合参数及决定系数

Table 2  lnU-1000 / T and lnUkin-1000 / T fitting parameters and determination coefficients for characteristic temperatures of Zr61Ti2Cu25Al12 alloy

Fitting formulaCharacteristic temperatureA2B / K4C / KT1 / Kr2
lnU-1000 / TTg-0.329231.62.0771.00.997
Tx0.8188892.891.0903.50.996
Tp0.3166443.862.61013.60.993
lnUkin-1000 / TTg-0.855827.91.8769.30.997
Tx-0.8916427.347.4899.10.997
Tp-1.3308220.731.8967.70.999

Note:A, B, C, T1─fitting parameters

新窗口打开| 下载CSV


η(T)=A0exp[C0 / (T-T2)]

式中，A0和C0为常数，T2为VFT温度，图5a中虚线所示为通过VFT方程拟合的η与T的关系曲线(-lnη-1000 / T)，拟合参数具体数值见表3。作为对比，由Cohen和Grest[34]的黏度公式得出的曲线(lnUkin-1000 / T)也包括在内，如图5a中短虚线所示，拟合参数具体数值见表2中的lnUkin-1000 / T。由此可知，通过上述方法研究非晶合金的晶化过程时同时考虑了热力学(ΔG)和动力学(η)因素，从图5a中可以看出，在中低温范围内，各曲线近似重合并与实验数据非常吻合，该温区内晶化受动力学因素控制，从而也证明了常规DSC忽略了对晶体生长的热力学影响，在熔点附近的高温区，曲线之间发生大的偏离，其归因于随温度升高热力学因素显著降低，尽管动力学因素增大，但其增大量小于热力学因素的显著减小量，从而使得lnU在达到最大值后迅速降低。在研究非晶合金晶化过程中，如上文所述，Tg只是晶化过程的先导，但是对整个超宽温度范围内过冷液体的晶化和黏性流动进行综合分析仍是有必要的。根据3.1节中提到的将非晶合金的玻璃化转变和晶化过程合并为单一激活过程，图5b为沿时间维度相关纵轴平移后拟合的曲线。可以看出，在超宽过冷液相区范围内，采用单一的激活过程可以很好地描述过冷液体的黏性流动和晶化过程，各拟合曲线r2均在0.98以上。

表3   Zr61Ti2Cu25Al12合金特征温度的-lnη-1000 / T拟合参数及决定系数

Table 3  -lnη-1000 / T fitting parameters and determination coefficient for characteristic temperatures of Zr61Ti2Cu25Al12 alloy

Characteristic temperature

A0

Pa·s

C0

K

T2

K

r2
Tg8.78353396.1514.70.991
Tx0.01844744.9464.30.997
Tp0.00955867.8421.20.997

Note:A0, C0, T2─fitting parameters

新窗口打开| 下载CSV


图6为玻璃形成熔体η随约化温度变化的Angell图，其中也包含了一些文献[36~38]中相关金属玻璃作为对比。在熔点附近的高温区域，Ukin ∝ η-1，但当温度逐渐降低接近Tg时，这种关系不再适用[20~23]，晶体生长速率可能会变得比通过上述黏度关系预测得更快。本工作表明，Zr61Ti2Cu25Al12非晶合金在Tg处η较1012 Pa·s低2~3个数量级，如图6中η-1曲线所示，表明其生长动力学与黏性流动间发生了解耦，这与文献[22,39]所报道的部分材料在低温Tg附近不符合此关系相一致，这种解耦可能与D和η之间的Stokes-Einstein关系的破坏有关，当高温合金液冷却至Tg时，在过冷液体内的不同位置以不同速率发生局部结构弛豫，即动力学在空间上是不均匀的，这种非均匀性的一个体现即是D和η之间的解耦。进一步，Ediger等[22]提出这种解耦可以表示为：Ukin ∝ η-ξ，其中0 < ξ < 1，即通过引入解耦指数(ξ)使得此关系在高温区和低温区都能得到很好的符合，表明了Ukin对η的幂律依赖性。本工作引入ξ = 0.84对原曲线进行调整使得温度在接近Tg时η达到1012 Pa·s，从而在由高温到低温的整个温度范围内很好地描述η和T之间的依赖关系，如图6中η-0.84曲线所示。从某种意义上讲，ξ是作为一个与液体强度正相关的参数而被引入的，其值越大越接近1，液体强度越强越接近Arrhenius行为，其值越小越接近0，液体脆度越大越偏离Arrhenius行为。本工作的Zr61Ti2Cu25Al12非晶合金ξ为0.84，说明其过冷液体具有一定的强度，通过ξ调整后的曲线在Angell图中所处的位置可以看出，该合金属于中等强度非晶合金，其η与T之间的依赖关系与其他锆基体系相似，尤其是接近Tg附近时，曲线斜率所表示的m ≈ 45，介于2个锆基和2个钯基之间，而与较脆的Zr40Ni60和纯金属相差较远。

图6

新窗口打开| 下载原图ZIP| 生成PPT

图6   本工作及相关文献[36~38]中玻璃形成熔体黏度随约化温度变化的Angell图

Fig.6   Angell plot for reduced temperature dependence of viscosity in several representative glass forming liquids[36~38] (The strongest SiO2 and the most fragile o-terphenyl as the upper and lower limits are also included)


据上文所述，ξ是作为一个与过冷液体强度正相关的参数被引入的，根据Ediger等[22]对一些有机和无机玻璃形成体的脆度分析，发现ξ与m近似成线性相关，如图7所示。本工作中Zr61Ti2Cu25Al12非晶合金的ξ-m关系基本符合包含极脆液体和极强液体的趋势线，其液体脆度与部分无机玻璃相当，ξ大于图中所列的大部分有机玻璃，说明该合金具有一定的“强”过冷液体特征，从而使其具有一定的玻璃形成能力，最大临界尺寸可达10 mm[8]。

图7

新窗口打开| 下载原图ZIP| 生成PPT

图7   解耦指数(ξ)与脆度系数(m)之间的关系

Fig.7   Decoupling exponent (ξ) representing the decoupling of crystal growth kinetics from viscous flow plotted as a function of the supercooled liquid m (GST—Ge2Sb2Te5)


4 结论

(1) 采用快速扫描量热和常规量热相结合的方法，对Zr61Ti2Cu25Al12非晶合金在5 × 10-2~5.5 × 104 K/s 6个数量级的Φh范围进行热流曲线测量，显示出其过冷液体随Φh变化的动力学行为：过冷液体的动力学行为滞后于温度的快速变化，在更高更宽的温度范围内，特征温度与Φh符合VFT方程。

(2) 相比于Tp附近高温的宽温度范围，Tg附近低温的窄温度范围内，Zr61Ti2Cu25Al12非晶合金过冷液体的结构变化较大，表现出更脆的液体行为，但从Tg到Tp的超宽温度范围来看，m的小幅变化(m = 35~47)意味着其过冷液体结构随温度变化比较平缓，从而表现出具有一定的“强”液体行为，使得该合金具有一定的玻璃形成能力；应用将玻璃化转变过程和晶化过程合并为单一转变过程的思想，通过时间维度坐标平移，得出从玻璃转变到熔点整个温度范围内的平均m ≈ 45。

(3) Zr61Ti2Cu25Al12非晶合金晶化过程中晶体生长的温度依赖性表明：生长激活能随温度升高逐渐降低，单位温度下的激活能约降为0.5 kJ/(mol·K)；晶体生长动力学与黏性流动在Tg附近发生解耦，这可能与动力学在空间的不均匀性有关，通过引入指数ξ = 0.84使得过冷液体从高温到低温较宽的温度范围内很好地符合η与T的依赖关系。

参考文献

Wang W H.

The nature and properties of amorphous matter

[J]. Prog. Phys., 2013, 33: 177

[本文引用: 2]

汪卫华.

非晶态物质的本质和特性

[J]. 物理学进展, 2013, 33: 177

[本文引用: 2]

Johnson W L.

Bulk glass-forming metallic alloys: Science and technology

[J]. MRS Bull., 1999, 24: 42

Li M X, Zhao S F, Lu Z, et al.

High-temperature bulk metallic glasses developed by combinatorial methods

[J]. Nature, 2019, 569: 99

Wang W H.

The elastic properties, elastic models and elastic perspectives of metallic glasses

[J]. Prog. Mater. Sci., 2012, 57: 487

Li C Y, Zhu F P, Ding J Q, et al.

Nanoindentation investigation on creep behavior of Zr-based bulk metallic glass

[J]. Rare Met. Mater. Eng., 2020, 49: 3353

Zhao Y C, Mao X J, Li W S, et al.

Microstructure and corrosion behavior of Fe-15Mn-5Si-14Cr-0.2C amorphous steel

[J]. Acta Metall. Sin., 2020, 56: 715

DOI      [本文引用: 1]

Amorphous steels exhibit ultra-high strength but room-temperature brittleness and strain-softening behavior as loading, which restricted the application of amorphous steels as high-performance structural material. Developing in situ crystals is an effective way to toughen the amorphous alloys. However, the crystals may sacrifice the corrosion resistance of amorphous steels. In this work, austenite and ferrite duel phases were introduced to the amorphous phase, via transformation induced plasticity (TRIP) of the austenite as loading, to enhance the ductility and improve the work-hardening behavior; and via the synergy of ferrite and amorphous phase to ensure the corrosion resistance. A novel amorphous steel Fe-15Mn-5Si-14Cr-0.2C was fabricated by magnetic suspension melting in a water-cooled copper crucible, and negative pressure suction casting into a copper mold. The microstructure and mechanical properties of the amorphous steel were characterized by XRD, EBSD and the electronic universal testing machine. The corrosion behavior in artificial seawater was studied on an electrochemical work station with a three-electrode system, and the corrosion morphology and corrosion products were characterized by SEM with EDS analysis. The results showed that the as-cast amorphous steel consisted of the amorphous matrix, CFe15.1 super-cooled austenite and Fe-Cr ferrite phases. From surface to inner, amorphous phases mainly exist in the margin, while crystalline phases are abundantly distributed in the center. The amorphous steel exhibited excellent comprehensive mechanical properties at room temperature, and its yield strength, fracture strength and plastic strain were up to 978 MPa, 2645 MPa and 35.8%, respectively. In artificial seawater, compared with 304 stainless steel, the amorphous steel showed high self-corrosion potential, low self-corrosion current density and high polarization resistance, large resistance arc radius, only one high frequency resistance arc and low corrosion kinetic rate. Moreover, the stable and dense passivation film was observed on the corrosion surface. Their excellent corrosion resistance and mechanical properties endow the amorphous steel with the potential to become a novel corrosion-resistant structural material for marine engineering.

赵燕春, 毛雪晶, 李文生 等.

Fe-15Mn-5Si-14Cr-0.2C非晶钢微观组织与腐蚀行为

[J]. 金属学报, 2020, 56: 715

DOI      [本文引用: 1]

采用水冷铜坩埚磁悬浮熔炼-铜模负压吸铸法制备了Fe-15Mn-5Si-14Cr-0.2C非晶复合材料棒状试样，通过XRD和EBSD对合金的微观组织进行表征，并研究试样室温压缩力学性能；采用电化学工作站三电极体系测试试样在人工海水中的腐蚀行为，并利用SEM和EDS观察和分析电化学腐蚀后的形貌及腐蚀产物。结果表明，Fe-15Mn-5Si-14Cr-0.2C非晶复合材料试样组织由非晶相+晶体相(CFe15.1过冷奥氏体相和Fe-Cr铁素体相)组成，试样在室温环境下的综合力学性能优异，屈服强度、断裂强度和塑性应变分别为978 MPa、2645 MPa和35.8%。试样在人工海水中表现出良好的耐蚀性，与304不锈钢相比，Fe-15Mn-5Si-14Cr-0.2C非晶复合材料自腐蚀电位大，自腐蚀电流密度低，极化电阻高，容抗弧半径大且只有一个高频容抗弧，只受电极电位的影响，腐蚀的动力学速率低，钝化膜稳定致密，具有成为新一代海洋工程耐蚀材料的潜力。

He Q, Cheng Y Q, Ma E, et al.

Locating bulk metallic glasses with high fracture toughness: Chemical effects and composition optimization

[J]. Acta Mater., 2011, 59: 202

[本文引用: 1]

He Q, Xu J.

Locating malleable bulk metallic glasses in Zr-Ti-Cu-Al alloys with calorimetric glass transition temperature as an indicator

[J]. J. Mater. Sci. Technol., 2012, 28: 1109

[本文引用: 2]

Li D F, Yang Y L, Shen Y, et al.

Bending fatigue behavior of thin Zr61Ti2Cu25Al12 bulk metallic glass beams for compliant mechanisms application

[J]. J. Mater. Sci. Technol., 2021, 89: 1

Li J, Shi L L, Zhu Z D, et al.

Zr61Ti2Cu25Al12 metallic glass for potential use in dental implants: Biocompatibility assessment by in vitro cellular responses

[J]. Mater. Sci. Eng., 2013, C33: 2113

[本文引用: 1]

Liu S S, Hou C N, Wang E G, et al.

Plastic rheological behaviors of Zr61Cu25Al12Ti2 and Zr52.5Cu17.9Ni14.6Al10Ti5 amorphous alloys in the supercooled liquid region

[J]. Acta Metall. Sin., 2021, 58: 807

[本文引用: 1]

刘帅帅， 侯超楠， 王恩刚 等.

Zr61Cu25Al12Ti2和Zr52.5Cu17.9Ni14.6Al10-Ti5块体非晶合金过冷液相区的塑性流变行为

[J]. 金属学报, 2021, 58: 807

[本文引用: 1]

Kissinger H E.

Reaction kinetics in differential thermal analysis

[J]. Anal. Chem., 1957, 29: 1702

[本文引用: 2]

Brüning R, Samwer K.

Glass transition on long time scales

[J]. Phys. Rev., 1992, 46B: 11318

[本文引用: 1]

Bai F X, Yao J H, Wang Y X, et al.

Crystallization kinetics of an Au-based metallic glass upon ultrafast heating and cooling

[J]. Scripta Mater., 2017, 132: 58

[本文引用: 1]

Yang Q, Peng S X, Bu Q Z, et al.

Revealing glass transition and supercooled liquid in Ni80P20 metallic glass

[J]. Acta Metall. Sin., 2021, 57: 553

[本文引用: 1]

杨 群, 彭思旭, 卜庆周 等.

非晶态Ni80P20合金的玻璃转变和过冷液体性质

[J]. 金属学报, 2021, 57: 553

[本文引用: 1]

Yang Q, Huang J, Qin X H, et al.

Revealing hidden supercooled liquid states in Al-based metallic glasses by ultrafast scanning calorimetry: Approaching theoretical ceiling of liquid fragility

[J]. Sci. China Mater., 2020, 63: 157

[本文引用: 1]

Orava J, Greer A L, Gholipour B, et al.

Characterization of supercooled liquid Ge2Sb2Te5 and its crystallization by ultrafast-heating calorimetry

[J]. Nat. Mater., 2012, 11: 279

DOI      PMID      [本文引用: 1]

Differential scanning calorimetry (DSC) is widely used to study the stability of amorphous solids, characterizing the kinetics of crystallization close to the glass-transition temperature T(g). We apply ultrafast DSC to the phase-change material Ge(2)Sb(2)Te(5) (GST) and show that if the range of heating rates is extended to more than 10(4) K s(-1), the analysis can cover a wider temperature range, up to the point where the crystal growth rate approaches its maximum. The growth rates that can be characterized are some four orders of magnitude higher than in conventional DSC, reaching values relevant for the application of GST as a data-storage medium. The kinetic coefficient for crystal growth has a strongly non-Arrhenius temperature dependence, revealing that supercooled liquid GST has a high fragility. Near T(g) there is evidence for decoupling of the crystal-growth kinetics from viscous flow, matching the behaviour for a fragile liquid suggested by studies on oxide and organic systems.

Chen Y X, Zhou D S, Hu W B.

Progress of differential scanning calorimetry and its application in polymer characterization

[J]. Acta Polym. Sin., 2021, 52: 423

[本文引用: 1]

陈咏萱, 周东山, 胡文兵.

示差扫描量热法进展及其在高分子表征中的应用

[J]. 高分子学报, 2021, 52: 423

[本文引用: 1]

Angell C A.

Formation of glasses from liquids and biopolymers

[J]. Science, 1995, 267: 1924

PMID      [本文引用: 1]

Glasses can be formed by many routes. In some cases, distinct polyamorphic forms are found. The normal mode of glass formation is cooling of a viscous liquid. Liquid behavior during cooling is classified between "strong" and "fragile," and the three canonical characteristics of relaxing liquids are correlated through the fragility. Strong liquids become fragile liquids on compression. In some cases, such conversions occur during cooling by a weak first-order transition. This behavior can be related to the polymorphism in a glass state through a recent simple modification of the van der Waals model for tetrahedrally bonded liquids. The sudden loss of some liquid degrees of freedom through such first-order transitions is suggestive of the polyamorphic transition between native and denatured hydrated proteins, which can be interpreted as single-chain glass-forming polymers plasticized by water and cross-linked by hydrogen bonds. The onset of a sharp change in d<r(2)>dT(<r(2)> is the Debye-Waller factor and T is temperature) in proteins, which is controversially indentified with the glass transition in liquids, is shown to be general for glass formers and observable in computer simulations of strong and fragile ionic liquids, where it proves to be close to the experimental glass transition temperature. The latter may originate in strong anharmonicity in modes ("bosons"), which permits the system to access multiple minima of its configuration space. These modes, the Kauzmann temperature T(K), and the fragility of the liquid, may thus be connected.

Ashkenazy Y, Averback R S.

Kinetic stages in the crystallization of deeply undercooled body-centered-cubic and face-centered-cubic metals

[J]. Acta Mater., 2010, 58: 524

[本文引用: 2]

Sun Y, Xi H M, Chen S, et al.

Crystallization near glass transition: Transition from diffusion-controlled to diffusionless crystal growth studied with seven polymorphs

[J]. J. Phys. Chem., 2008, 112B: 5594

[本文引用: 1]

Ediger M D, Harrowell P, Yu L.

Crystal growth kinetics exhibit a fragility-dependent decoupling from viscosity

[J]. J. Chem. Phys., 2008, 128: 034709

[本文引用: 5]

Nascimento M L F, Zanotto E D.

Does viscosity describe the kinetic barrier for crystal growth from the liquidus to the glass transition?

[J]. J. Chem. Phys., 2010, 133: 174701

[本文引用: 2]

Zhuravlev E, Schick C.

Fast scanning power compensated differential scanning nano-calorimeter: 1. The device

[J]. Thermochim. Acta, 2010, 505: 1

[本文引用: 1]

Zhuravlev E, Schick C.

Fast scanning power compensated differential scanning nano-calorimeter: 2. Heat capacity analysis

[J]. Thermochim. Acta, 2010, 505: 14

[本文引用: 1]

Kelton K F.

Analysis of crystallization kinetics

[J]. Mater. Sci. Eng., 1997, A226-228: 142

[本文引用: 2]

Lasocka M.

The effect of scanning rate on glass transition temperature of splat-cooled Te85Ge15

[J]. Mater. Sci. Eng., 1976, 23: 173

[本文引用: 1]

Vogel H.

The law of the relation between the viscosity of liquids and the temperature

[J]. Phys. Zeit., 1921, 22: 645

[本文引用: 2]

Fulcher G S.

Analysis of recent measurements of the viscosity of glasses

[J]. J. Am. Ceram. Soc., 1925, 8: 339

Tammann G, Hesse W.

Die abhängigkeit der viscosität von der temperatur bei unterkühlten flüssigkeiten

[J]. Z. Anorg. Allg. Chem., 1926, 156: 245

[本文引用: 2]

Bohmer R, Angell C A.

Correlations of the nonexponentiality and state dependence of mechanical relaxations with bond connectivity in Ge-As-Se supercooled liquids

[J]. Phys. Rev., 1992, 45B: 10091

[本文引用: 1]

Perera D N, Tsai A P.

Thermal and viscoelastic properties of a strong bulk metallic glass former

[J]. J. Phys., 2000, 33D: 1937

[本文引用: 2]

Chen H S.

A method for evaluating viscosities of metallic glasses from the rates of thermal transformations

[J]. J. Non-Cryst. Solids, 1978, 27: 257

[本文引用: 1]

Cohen M H, Grest G S.

Liquid-glass transition a free-volume approach

[J]. Phys. Rev., 1979, 20B: 1077

[本文引用: 2]

Angell C A, Sichina W.

Thermodynamics of the glass transition: Empirical aspects

[J]. Ann. N. Y. Acad. Sci., 1976, 279: 53

[本文引用: 1]

Busch R, Schroers J, Wang W H.

Thermodynamics and kinetics of bulk metallic glass

[J]. MRS Bull., 2007, 32: 620

[本文引用: 3]

Waniuk T A, Busch R, Masuhr A, et al.

Equilibrium viscosity of the Zr41.2Ti13.8Cu12.5Ni10Be22.5 bulk metallic glass-forming liquid and viscous flow during relaxation, phase separation, and primary crystallization

[J]. Acta Mater., 1998, 46: 5229

Busch R, Gallino I.

Kinetics, thermodynamics, and structure of bulk metallic glass forming liquids

[J]. JOM, 2017, 69: 2178

[本文引用: 3]

Alba C, Busse L E, List D J, et al.

Thermodynamic aspects of the vitrification of toluene, and xylene isomers, and the fragility of liquid hydrocarbons

[J]. J. Chem. Phys., 1990, 92: 617

[本文引用: 1]

/

〈 〉


版权所有 © 《金属学报》编辑部
地址: 沈阳市文化路72号, 中国科学院金属研究所(110016)
电话: +86- 024-23971286 　E-mail: jsxb@imr.ac.cn
本系统由北京玛格泰克科技发展有限公司设计开发 技术支持：support@magtech.com.cn