Isothermal
vertical solidus line in the phase diagram of peritectic binary systems
(s. Peritectic) which gives the peritectic temperature.
For
example, the iron-carbon phase diagram shows three isothermal reactions,
one peritectic (HIB line), one eutectic (ECF line) and one eutectoid
reaction (PSK line).
Additional references:
Peritectic
Peritectoid
Eutectic
Eutectoid