Influence of Interstitials on the mechanical properties of group IV b metals

Abstract

THE spectacular progress in nuclear technology and space science researches has brought in a vigorous inte-rest in the properties of IV b metals, titanium, zir- conium and hafnium and their alloys. In most of the engineering applications, the properties of pure metals themselves would be clearly insufficient:alloying with other elements would be called for, be it for increase in strength and fracture toughness, or for better super conducting properties. Group IV b metals are somewhat unique in their alloying behaviour as they form solid solutions not only with substitutional alloying additions, but also rather extensively with interstitial elements hydrogen, carbon, oxygen and nitrogen. Generally, these elements are not soluble to any remarkable degree in metals and they readily form second phase compounds when present over few parts per million. IV b metals, perhaps helped by their crystal structure and accompanying large interstices, are able to accommodate these elements in their original lattices themselves, thus leading to dras-tic alterations in their mechanical and physical prop-erties. It is the purpose of this review to consider the influence of interstitials on the mechanical properties of group IV b metals. This must be of recurrent interest to those engaged in investigations connected with the metallurgy of Ti, Zr and Hf and their alloys.