Sulphuric precipitates in novel titanium-based, sulphur-bearing bulk metallic glass - a BMG composite?

• Published in: Philosophical magazine letters Vol. 104; no. 1
• Main Authors: Adam, Bastian, Kuball, Alexander, Ruschel, Lucas Matthias, Neuber, Nico, Frey, Maximillian, Busch, Ralf
• Format: Journal Article
• Language: English
• Published: Abingdon Taylor & Francis 31.12.2024; Taylor & Francis Ltd; Taylor & Francis Group
• Subjects: Alloy systems; Alloying elements; Amorphous materials; Biomedical materials; BMG; Copper; Corrosion effects; Corrosion resistance; Corrosion resistant alloys; crystallisation; Crystallization; Glass; Glass formation; Intermetallic compounds; Metallic glasses; Precipitates; primary phase; Solidification; Sulfur; sulphuric precipitates; Titanium base alloys
• DOI: 10.1080/09500839.2024.2376614
• ISSN: 0950-0839

New titanium-based metallic glasses containing sulphur as a key element have recently been developed and are the subject of ongoing research related to the effects of sulphur introduction into glass-forming alloy systems. Here we report on the formation of sulphuric precipitates during solidification of a Ti 40 Zr 35 Cu 17 S 8 alloy and on the occurrence of secondary intermetallic compound crystallization starting in sulphur-depleted zones around the precipitates. The alloy is a promising metallic glass for use as a structural and biomedical material as it shows a high yield strength and good corrosion resistance paired with a low density. The role of sulphur for the glass formation in the Ti-Zr-Cu-S system is discussed and specimens quenched into different structural states are investigated by means of high-energy synchrotron diffraction and electron microscopy. The electron microscopic findings reveal that sulphuric precipitates precede the crystallization of an intermetallic (Ti, Zr) 2 Cu phase, which is the primary phase when sulphur is not present in the system and thus lead to a higher glass-forming ability. The sulphuric precipitates are found in specimens of various casting thickness and differ in their volume percentages depending on the size of the cast sample, while the secondary phase (Ti, Zr) 2 Cu crystallizes heterogeneously in the interfaces between the sulphuric precipitates and the local matrix.