Definition of the contents of components on a triangle of concentration in systems of binding materials.

Lecture № 25 ФХС. Theme: The basic types of the diagram of condition of treecomponent systems and rule of job with them. Definition of the contents of components on the triangle of concentration in systems of binding materials.

Point of structures of chemical connections.

Are in corners of a triangle of concentration АВС. The points of structures of double binary connections formed by two any components of system settle down on the parties of a triangle of concentration. The points of structures of threefold connections formed by three components of system are inside a triangle of concentration (А1В1С1)

 

3. Boundary curves and fields primary кристаллизации.

All field of a triangle of concentration is divided(shared) by boundary curves - ab, ef fc, cg, cd, gd on a number(line) of sites named by fields primary кристаллизации (k-n-e-b-a-k), (b-e-f-c-d-b), (d-c-g-d).

 

4. The threefold points are three converging boundary curves on the diagrams of a condition form threefold points bef, in which if кристаллизация is not completed in balance there are 4 phases is a liquid of structure of this point and three crystal connections, the fields кристаллизации which are in this point.

In a threefold point "b" in balance of a liquid phase is crystals АВ, АС, А1В1С1 in balance of a liquid phase with are crystals АВ, АС, А1В1С1.

 

5. Connecting direct and elementary triangles. Connecting direct are direct lines on трехкомпонентных the diagrams of a condition connecting points of structures of individual chemical connections having complex(difficult) fields primary кристаллизации. For example, АВ - А1В1С1; А1В1С1 - АС.

 

6. Бинодальные curves - if in one of private(individual) double systems А-С of components трехкомпонентную system there is an area ликвации, contiguous to the party АС of a triangle limited line Рm, Pl is called бинодальной by a curve.

 

7. Curves of polymorphic transformations - at constant temperature coincides with изотермой to appropriate temperature of polymorphic transformation. For example: the component In has two polymorphic updatings In 'B' with temperature transformation 1500 With, a curve of polymorphic transformation will coincide on трехкомпонентной to the diagram of a condition with a line изотермы qS appropriate 1500С.

 

 

 

 

As it was already marked, the diagrams of a condition allow first of all to define way crystallization and way melting, and for the same structure graphically these ways are identical, but are opposite on a direction and sequence of phase transformations. Therefore at construction of a way melting on three-component the diagrams of a condition often it happens expedient to define a way crystallization of the appropriate structure before its complete hardening in a final point crystallization, and then, beginning from this point to do the same way in the opposite direction, meaning, that the phase transformations, occurring in equilibrium conditions, at cooling (way crystallization) are opposite on the character to transformations occurring at heating (a way melting). For example, if at cooling occurs crystallization any of connection, at heating occurs melting of its crystals. If at cooling there is an allocation of any crystals for the bill interaction between allou and before the dropped out firm phase, at heating, on the contrary, there is decomposition these crystalls and etc.

Rules of job with three-component by the diagrams of a condition on separate types of these diagrams in their common expression are considered below. The specified rules are considered in that sequence, which usually should adhere at definition of ways of phase changes.

 

 

 

 

 

 

For definition of the contents any of a component, for example A (the fig. 1), in three-component allou (or total contents of components in firm phases), answering to the given figurative point М, through this point is necessary to lead a straight line ab, parallel opposite (in relation to top of a triangle with %100 contents of this component, i.e. А) party ВС of a triangle of concentration. This straight line cuts on two other parties АВ and АС of a triangle equal pieces (аВ and bС), which characterize the contents of a component A (in this case 30 %).

Precisely as for definition of the contents of components B and C are spent the appropriate straight lines parallel the parties АС (a straight line cd) and АВ (a straight line ef), contents of components B and C will be defined(determined) accordingly by pieces сА (or dC) and еА (or fB) (in this case 50 % B and 20 % С).

From a fig. 1 it is easy to be convinced, that the definition of the contents of components can be made easier on any one party of a triangle of concentration. For this purpose from the given point М to any one party of a triangle, for example АС, the pieces Me and Mb parallel two other parties of a triangle are spent therefore the first party АС will be broken on three pieces appropriate to the contents of all three components - the contents A will define a piece bС - 30 %, C - piece еА- 20 % and B - piece bе- 50 %.