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Indexed by:期刊论文

Date of Publication:2017-02-27

Journal:MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

Included Journals:SCIE、EI、Scopus

Volume:687

Page Number:1-7

ISSN No.:0921-5093

Key Words:Titanium alloys; phase transformation; electron microscopy; beta structrual stability; Young's modulus

Abstract:Multi-element alloying is of great importance to the structural stability of metastable beta-Ti alloys with low Young's modulus. The present work investigates the effects of Nb and Zr alloying on the beta stability of the [(Mo0.5Sn0.5)-(Ti,Zr)(14)](Nb,Zr)(1,2) alloy series, according to the cluster formula approach for designing solid solution alloys. Alloy rods with a diameter of 6 mm were prepared by copper-mold suction-casting method. The contributions of Nb and Zr to the beta stability, characterized with the equivalent coefficients in a Mo equivalent (Mo-eq) formula, are modified from the viewpoint of phase diagram features. Thus, the beta stabilities of Ti alloys with the updated Moeq are consistent with the experimental results. The Young's moduli of the metastable beta-Ti alloys decrease first to a low value with increasing Moeq, and then increase up to a constant level. It is reconfirmed that the lowest Young's modulus (48 GPa) of the beta-[(Mo0.5Sn0.5)-(Ti13Zr1)]Nb-1 alloy benefits from its lower Mo-eq (13.6 wt% Mo), which is slightly higher than the critical limit for beta stabilization to inhibit alpha" martensite. Multi-component alloys with Mo-eq below this value will show a double yielding phenomenon due to the stress-induced alpha" martensite and/or beta twins during the tension process.