Search results
Results From The WOW.Com Content Network
A eutectic system or eutectic mixture (/ j uː ˈ t ɛ k t ɪ k / yoo-TEK-tik) [1] is a type of a homogeneous mixture that has a melting point lower than those of the constituents. [2] The lowest possible melting point over all of the mixing ratios of the constituents is called the eutectic temperature.
The solid–liquid phase boundary can only end in a critical point if the solid and liquid phases have the same symmetry group. [5] For most substances, the solid–liquid phase boundary (or fusion curve) in the phase diagram has a positive slope so that the melting point increases with pressure.
A deeper eutectic or more rapid cooling will result in finer lamellae; as the size of an individual lamellum approaches zero, the system will instead retain its high-temperature structure. Two common cases of this include cooling a liquid to form an amorphous solid , and cooling eutectoid austenite to form martensite .
The solidus is the locus of temperatures (a curve on a phase diagram) below which a given substance is completely solid (crystallized). The solidus temperature specifies the temperature below which a material is completely solid, [2] and the minimum temperature at which a melt can co-exist with crystals in thermodynamic equilibrium.
During a phase transition of a given medium, certain properties of the medium change as a result of the change of external conditions, such as temperature or pressure. This can be a discontinuous change; for example, a liquid may become gas upon heating to its boiling point, resulting in an abrupt change in volume. The identification of the ...
Eutectoid steel can in principle be transformed completely into pearlite; hypoeutectoid steels can also be completely pearlitic if transformed at a temperature below the normal eutectoid. [6] [7] Pearlite can be hard and strong but is not particularly tough. It can be wear-resistant because of a strong lamellar network of ferrite and cementite.
Those eutectic metals are alloys that transform directly from solid to liquid state, or vice versa from liquid to solid state, at a specific composition and temperature without passing a two-phase equilibrium, i.e. liquid and solid state. The fact that the eutectic temperature can be much lower than the melting temperature of the two or more ...
It shows a eutectic and a eutectoid; these phases crystallise as a stacking of fine strips of pure phases (iron and cementite) in case of the eutectoid, or a pure iron containing small balls of cementite for the eutectic. Although it is heterogeneous, these phases behave like homogeneous pure bodies.