11. Main causes of uncertainty in equilibrium diagrams

11.1 Imprecision in certain areas

In many diagrams, the limits of certain domains are indicated by dotted lines, meaning that they are not known with sufficient precision. This is mainly the case for high and low temperatures. In the case of high temperatures, this inaccuracy is mainly due to pollution of the alloy either by the atmosphere used, or by the materials of the crucibles containing the alloys, mainly in the case of highly reactive refractory metal alloys (Cr, Ti, etc.), but also to difficulties in measuring high temperatures, and solidification conditions. At low temperatures, the main problem is the slowness of certain solid-state transformations, and even more so of solid-state diffusion. For some regions difficult to determine in certain diagrams, the limits of the domains...