Optimizing the Elastic Modulus Temperature Coefficient of Ti-45Nb Alloy by Aging-Induced Nano-Precipitation α Phase

Titanium-Niobium alloys have garnered extensive interest in various fields, such as aerospace, medical equipment, and scientific research instruments, due to their superior properties. Particularly, their anti-magnetic characteristics render them high potential in the watchmaking industry. The temperature coefficient of the elastic modulus of balance spring materials is a crucial parameter for assessing the impact of temperature on the properties of TiNb alloys. This study aims to explore the influence of heat treatment on the microstructural and elastic modulus temperature coefficient of the Ti-45Nb alloy. The results indicate that after short-term aging treatment, ω particles are enriched at grain boundaries and defects and are distributed in a necklace shape after erosion. After long-term aging treatment, the α phase appears in the material. The phase transformation process of low-temperature aging is β → β + β' → β + ω → β + ω + α. The grain size of the material does not change significantly after different treatments. Additionally, the effect of heat treatment on material properties was studied by a low-temperature dynamic elastic modulus tester. The results showed that the temperature coefficient of the elastic modulus of the material in its original state was relatively high, ranging from 50~220 × 10^-6·°C^-1. After long-time aging treatment, the temperature coefficient of the elastic modulus of the material decreased significantly due to the appearance of the α phase. The temperature coefficient of the elastic modulus of the material after 48 h of heat preservation treatment fluctuated at 0 ± 30 × 10^-6·°C^-1. The internal control standard of excellent products in the industry is -11~35 × 10^-6/°C. This study provides significant practical implications for the application of Ti-45Nb alloy in the watchmaking industry by adjusting the heat treatment temperature and time to study the effects on organizational evolution and the temperature coefficient of the elastic modulus.