Alloying and sintering of manganese steels in terms of high manganese vapour pressure

Abstract

Every chemical element is characterised by its physical–chemical property – vapour pressure – the actual value of which depends only on temperature. The temperature dependence of the vapour pressure of some metals used in industry, including those used in powder metallurgy as alloying elements or base metals, is shown in Fig. 3.1.Some crystalline materials exhibit a relative high vapour pressure which attains the barometric pressure at the temperature lower than their melting point. For this reason it is not possible to attain the melting point by heating at the pressure of one atmosphere because at such a pressure they proceed directly into the gas phase. This state change is sublimation and the temperature at which the vapour of the solid material reaches the pressure of one atmosphere is the normal sublimation point. The vapour pressure of a liquid (the same also for solid sublimating matter) does not depend on the presence of an inert gas in the space over the liquid which will be saturated by the gas of the liquid phase in that space should therefore be evacuated.