The Titanium–Niobium System

Abstract

THE titanium–niobium system appeared to be very suitable for an examination of the formation and ageing characteristics of martensitic α because published results suggested that an essentially martenstic α structure should be obtained on quenching alloys lying within a fairly wide composition range. A series of titanium–niobium alloys (0–25 at. per cent niobium) was prepared from spectroscopic ally pure niobium and titanium sponge (as melted hardness 85–90 Brinell hardness number) by tungsten electrode arc melting under 20 cm argon. The 25 g buttons produced were melted twice using a current of 300 amp, and were held molten for at least 1 min during each cycle. The buttons were homogenized in vacuum at 1,000° C for 24 h and then pressed to disks about 0.15 in. thick at temperatures which, according to the published results¹, were within the β field. To reduce contamination the buttons were heated in pure argon prior to pressing, and were exposed to air for the minimum possible time.