Combinatorial Searching for Pt-Zr-Ni Thin Film Amorphous Alloys for Glass Lens Mold

Abstract

AbstractRecently, the materials of functional optical glass lens mold have been studied. We had searched for the novel amorphous alloy having high crystallization temperature Tx using combinatorial arc plasma deposition (CAPD). In the previous work, Ru-based and Pt-based alloys were investigated. Although these amorphous alloys had high Tx of more than 973 K, they did not show good machinability. In this work, in order to progress machinability of amorphous samples, the various properties of the Pt-Zr-Ni thin film amorphous alloys were investigated. The properties of desired sample were as follows: (1) Tx exceeds 923K. (2) sf exceeds 2.0GPa. (3) Non-sticking characteristics with melting glass. (4) Good machinability.As the process of searching for amorphous alloys, 3267 samples were deposited by CAPD. The phase and composition of the CAPD samples with thickness more than 500nm were evaluated. Thickness of the CAPD samples was measured by a white-light interferometer. Compositions were measured by an energy dispersive X-ray fluorescence spectrometer. Phases were identified by an X-ray diffractmeter. From these results, 312 amorphous compositions were found. The period of searching for amorphous composition was only about twenty days. This shows the effectiveness of CAPD.Tx and fracture stress Ðf of the sputter-deposited amorphous samples having the same composition as amorphous CAPD samples were measured because CAPD samples were too small to evaluate thermal and mechanical properties. Tx was measured by differential scanning calorimeter. sf was measured by tensile tests using a thermo-mechanical analyzer.At first, in order to investigate the effect of Pt-content on Tx, the PtxZr (90-x)Ni10 samples were fabricated by the sputter. Pt-content was ranged from 20 to 50 at.%. Tx increased with increasing Pt-content, and the Pt51Zr39Ni10 sample showed the highest Tx of 939K. The sample has needs to show Pt-rich composition to show Tx of more than 923K. However, sf of all sample showed less than 2GPa.Subsequently, in order to search for Pt-rich sample having high sf, the properties of the Pt50Zr(50-x)Nix sample were investigated. Ni-content was ranged from 5 to 15 at.%. As the results, Tx increasing with increasing Ni-content. The Pt50Zr36Ni14 sample showed the highest Tx of 985 K and Ðf of 2.12 GPa.Sticking characteristics of the Pt50Zr36Ni14 sample with melting glass were measured. Melting glass was felled in drops on the samples, and then droplet was removed without adhering to the sample. Machinability of the Pt50Zr36Ni14 sample was evaluated by cutting tests using diamond tools. Surface roughness of this sample worked was several nanometers. This result indicated that the Pt50Zr36Ni14 sample showed good machinability. From these results, it is considered that the Pt50Zr36Ni14 sample is suitable for the materials for glass lens mold.