Applying composition control to improve the mechanical and thermal properties of Zr–Cu–Ni–Al thin film metallic glass by magnetron DC sputtering

Abstract

This study is intended to investigate the amorphicity region of Ni+Al content in Zr–Cu–Ni–Al thin film. The thermal and mechanical performances of Zr–Cu–Ni–Al thin film metallic glass (TFMG) are also addressed. By adjusting target power, thin film metallic glass with various (Zr+Cu)/(Ni+Al) ratio were fabricated. The composition of the Zr–Cu–Ni–Al thin films was analyzed by field emission electron probe micro-analyzer (FE-EPMA). Via Grazing Angle X-Ray Diffractometer (GIXRD), all Zr–Cu–Ni–Al thin films show the hump peak, implying the amorphous feature. To further identify the amorphous characteristic, a differential scanning calorimetry (DSC) is used and the amorphicity region of (Ni+Al) in Zr–Cu–Ni–Al thin film is as wide as 54at.%. Besides, the glass transition temperature Tg, for all Zr–Cu–Ni–Al TFMGs are above 700K, and the △T ranges from 50K to 70K. With the aid of nano-indention, hardness and elastic modulus were measured in which the hardness reaches 7.5GPa for Zr23Cu23Ni27Al27 TFMG. The value of △T increases with (Ni+Al) contents in Zr–Cu–Ni–Al TFMG across the whole amorphous region, indicating that the thermal stability is improved and higher hardness is thus achieved. For a better intrinsic viewpoint, the average interatomic distance is calculated. The calculated distance gets closer with Ni+Al content, which might result from the increase of short range order (SRO) structure with good thermal stability. From the positive correlation of elastic modulus and Ni+Al content, the improved hardness is explained in the viewpoint of energy. In summary, the thermal and mechanical performances of Zr–Cu–Ni–Al TFMG with 54at.% (Ni+Al) content are among the best in the class of Zr–Cu–Ni–Al metallic glass, implying that Zr–Cu–Ni–Al TFMG with improved performance can be fabricated in lower cost.