Development of allergy-free titanium alloys for brass instruments and their characteristics

Abstract

Binary titanium alloys containing Nb or Ta, which are allergy-free and non-toxicity elements, were fabricated, and then the possibility of their application to various music instruments made of brass was investigated by the evaluation of corrosion characteristics, elastic modulus-density ratio (E/ρ), resonance frequency (f) and internal friction (Q -1). The practical models of the mouthpieces of the trumpets made of the binary titanium alloys were also fabricated by precision casting method in order to compare directly with the sound characteristics of those made of brass and commercially pure Ti. The critical current density for the passivation of the Ti-Nb and Ti-Ta system alloys is approximately 40% lower than that of brass and nearly equal to or a little higher than that of commercially pure Ti. The Q -1 of the Ti-Nb and Ti-Ta system alloys with α″ phase drastically increase. The E/ρ and f of the Ti-Nb and Ti-Ta system alloys exhibit a positive relationship. The sound characteristics of practical mouthpieces of trumpets for a bass instrument can be controlled by changing the E/ρ and/of the alloys.