Thermal stability of the Ti-Zr-Cu-Pd nano-glassy thin films
Thermal stability of the Ti-Zr-Cu-Pd nano-glassy thin films
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DOI：
10.1016/j.jallcom.2017.11.387
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发表时间：
2018-02
影响因子：
6.2
通讯作者：
M. Mohri;Di Wang;J. Ivanisenko;H. Gleiter;H. Hahn
中科院分区：
文献类型：
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作者：
M. Mohri;Di Wang;J. Ivanisenko;H. Gleiter;H. Hahn
纳米玻璃薄膜由纳米尺寸的玻璃区（团簇）组成，其结构与熔融淬火玻璃和非晶界面区域相对应，其特征是密度降低或局部自由体积增加，并且在许多情况下化学成分经过修饰。采用直流磁控溅射技术在Si衬底上合成了Ti-Zr-Cu-Pd纳米玻璃薄膜。分析了溅射条件（溅射功率和氩气压力）对沉积膜的纳米和微观结构以及热行为的影响。在低Ar压力（0.2 Pa）下溅射时，薄膜呈现出均匀的非晶结构，而在高Ar压力（0.5-0.8 Pa）下溅射时，薄膜呈现出具有不同尺寸玻璃团簇的纳米玻璃结构。当氩气压力升高时，玻璃团簇的平均尺寸随界面体积分数的增加而减小。用差示扫描量热法（DSC）在加热速率高达40 Kmin−1时测定玻璃化转变和结晶温度。通过在高于玻璃化转变温度和结晶温度下的退火，研究了薄膜的热稳定性。采用x射线衍射、扫描电镜和透射电镜对薄膜的微观结构进行了研究。结果表明，纳米玻璃薄膜比均匀玻璃薄膜具有更高的热稳定性。纳米玻璃薄膜中界面组分体积分数的增加会导致超稳定的热行为，这表明纳米玻璃界面的存在阻碍了结晶。
Nano-glassy thin films consist of nanometer-sized glassy regions (clusters) with a structure corresponding to melt-quenched glasses and amorphous interfacial regions characterized by a reduced density, or locally enhanced free volume, and in many cases a modified chemical composition. Ti-Zr-Cu-Pd nano-glass thin films were synthesized by using direct current (DC) magnetron sputtering on Si substrates. The influence of the sputtering conditions (sputtering power and Ar gas pressure) on the nano- and microstructure of deposited films and on their thermal behavior was analyzed. The thin films were noted to exhibit a homogeneous amorphous structure when sputtered at low Ar pressure (0.2 Pa) and a nano-glass structure with various sizes of the glassy cluster at higher Ar pressures (0.5–0.8 Pa). By raising the Ar pressure, the average size of the glassy clusters was noted to decrease corresponding to an increase of the volume fraction of the interfacial regions. The glass transition and crystallization temperatures were determined by using differential scanning calorimetry (DSC) at heating rates up to 40 Kmin−1. The thermal stability of the thin films was studied by annealing at temperatures above the glass transition and crystallization temperatures. The microstructure of the thin films was studied by means of X-ray diffraction, scanning electron microscopy (SEM) and transmission electron microscopy. The results obtained indicate that the nano-glassy thin films exhibit higher thermal stability than homogeneous glassy thin films. The fact that an increase of the volume fraction of the interfacial component in nano-glassy thin films results in an ultra-stable thermal behavior is indicating that the presence of nano-glassy interfaces impedes crystallization.