1. eutectoid - Noun
2. eutectoid - Adjective
eutectoid (not comparable)
Describing the phase-change reaction of an alloy in which, on cooling, a single solid phase transforms into two other solid phases.
eutectoid (plural eutectoids)
An alloy of a composition that undergoes the eutectoid transformation.
When steels with exactly 0.8% carbon (known as a eutectoid steel), are cooled, the austenitic phase (FCC) of the mixture attempts to revert to the ferrite phase (BCC). Source: Internet
In a hypereutectoid composition (greater than 0.8% carbon), the carbon will first precipitate out as large inclusions of cementite at the austenite grain boundaries and then when the composition left behind is eutectoid, the pearlite structure forms. Source: Internet
The inverse of this, when one solid phase transforms into two solid phases during heating, is called the eutectoid. Source: Internet
The same process, but beginning with a solid instead of a liquid is called a eutectoid transformation. Source: Internet