Elastic moduli of cast Ti–Au, Ti–Ag, and Ti–Cu alloys

Objectives This study investigated the effect of alloying titanium with gold, silver, or copper on the elastic properties of the alloys. Methods A series of binary titanium alloys was made with four concentrations of gold, silver, or copper (5, 10, 20, and 30 mass%) in an argon-arc melting furnace. The Youngʹs moduli and Poissonʹs ratios of the alloy castings were determined with an ultrasonic-pulse method. The density of each alloy was previously measured by the Archimedesʹ principle. Results were analyzed using one-way ANOVA and the Schefféʹs test. Results The densities of Ti–Au, Ti–Ag, and Ti–Cu alloys monotonically increased as the concentration of alloying elements increased. As the concentration of gold or silver increased to 20%, the Youngʹs modulus significantly decreased, followed by a subsequent increase in value. As the concentration of copper increased, the Youngʹs modulus monotonically increased. The Youngʹs moduli of all the Ti–Cu alloys were significantly higher than that of the titanium. Significance The density of all the experimental alloys was virtually independent of the alloy phases, while the Youngʹs moduli and Poissonʹs ratios of the alloys were dependent. The addition of gold or silver slightly reduced the Youngʹs modulus of the titanium when the alloy phase was single α. The increase in the Youngʹs modulus of the Ti–Cu alloys is probably due to the precipitation of intermetallic compound Ti2Cu. Copper turned out to be a moderate stiffener that gains a Youngʹs modulus of titanium up to 20% at the copper concentration of 30 mass%.