A Ti 43 Zr 7 Cu 43 Ni 7 bulk metallic glass (BMG) exhibits a plastic strain of less than 0.2% under room-temperature compression. However, a Ti 45 Zr 5 Cu 40 Ni 7.5 Sn 2.5 BMG developed by addition of Sn to Ti 43 Zr 7 Cu 43 Ni 7 shows a significant improvement of $14.8% to the plastic strain with work hardening. Microstructural comparison of these BMGs reveals that the addition of Sn leads to formation of nano-scale chemical heterogeneities throughout the material. These nano-scale chemical fluctuations play an important role in enhancing the plastic strain of (Ti-Cu)-based BMGs.
Influence of N 2 partial pressure on the microstructure, hardness, and thermal stability of CrZrSiN nanocomposite coatings The effects of N 2 partial pressure in the unbalanced magnetron sputtering process on the microstructure, hardness, and thermal stability of the CrZrSiN nanocomposite coating were investigated. A typical nanocomposite structure, composed of a crystalline phase and an amorphous phase was obtained and the distribution of these phases changed with increasing N 2 partial pressure. The N 1s spectra revealed the presence of two-peak characteristic of nitrogen in the CrZrN and SiN x phases, and the ratio of the peak's SiN x to CrZrN intensity increased with increasing N 2 partial pressure, indicating an increase in the amorphous phase in the nanocomposite microstructure. As N 2 partial pressure increased, the CrZrSiN coating hardness decreased from 38 to 30 GPa due to the increasing amount of the SiN x amorphous phase. After the thermal stability test, the hardness values of the CrZrSiN coatings were maintained at approximately 30 GPa up to 800 °C, but the hardness decreased rapidly to 18 GPa after annealing at 900 °C. This drastic change of hardness over 900 °C was due to the formation of a Cr 2 O 3 phase in the CrZrSiN coating.
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