Types of phase diagrams

Types of phase diagrams

• 2.
   Two metalsare completely soluble in the solid state, the type od solid phase formed will be substitution solid solution.  The diagram show the series of cooling curves for different alloys in a completely soluble system. The dotted lines the form of phase diagram.  The diagram plotting temperature vs. composition.
• 3.
   The coolingcurves pure metals A and B show only a horizontal line because the beginning and end of solidification take place at constant temperature.  These cooling curves show two changes in slope.  The first break is at temperature T1, which indicates beginning od solidification and lower break at T2 indicates end of solidification  The two points TA and TB represent the freezing point at two pure metals
• 4.
   Liquids line:is upper line showing the beginning of solidification  Solidus line: is the lower line showing the end of solidification.  Between the liquids and solidus lines there exists a two phases region.  Two phase region does not give any information regarding mixture  In order to determine this information, It is necessary to apply two rules.
• 5.
   Rule-1: Chemical compositionof phases  To determine the actual chemical composition of the phases of an alloy in equilibrium at any specified temperature in two phases region, draw horizontal temperature line called tie line  Draw the tie line mo to the boundaries of the field  Point m the intersection of the tie line with the solidus line, when dropped to base line, give the composition od phase that exits boundary.  Similarly, point O, when dropped to base line, will give the composition of the other phase constituting the mixture, in this liquid solution of composition.
• 6.
   Rule-2: Relative amountof each phases  To determine the relative amounts of the two phases in equilibrium at specified temperature in a two phase region  A vertical line represting the alloy and horizontal temperature line to the boundaries of the field.  The vertical line will divide the horizontal line into two parts whose length are inversely proportional to amount of phases present. This is also known as the lever rule.  The lever rule may be expressed mathematically as
• 7.
   This typeof phase diagram is produce, when the two alloy components A and B are completely soluble in the liquid state but completely insoluble in solid state.  The points M and N indicate the melting points of two pure metals.  T1 show the beginning of solidification and TE end of solidification.  MEN is liquidus line and show beginning of solidification.  The point at which the liquidus lines intersect the minimum point E, is known as the eutectic point. TE is called eutectic temperature.
• 8.
   This phase diagramconsists of four areas.  The area above the liquids line is a single-phase homogenous liquid solution.  The remaining three areas are two phase areas  The alloys to left of the eutectic composition as hypoeutectic alloys and those to right as hypereutectic alloys.
• 9.
   Alloy 1:is eutectic composition  It is cooled from temperature To it remains a uniform liquid solution until the point E, the eutectic temperature line is reached  The eutectic reaction may be written as
• 10.
   The amountof percentage A and L determine by lever rule
• 11.
   This typeof phase diagram show the partial solid solubility.  TA and TB indicate the melting points of two pure metals.  TAETB is liquids line and TAFEGTB show solidus line  Above the liquids line, the is only single phase liquid solution.  The lines FH and GH show that with the deceasing the temperature the maximum amount of solute can be dissolve deceases.
• 12.
   In alloy1: liquids line is cross T1 it will begin to solidify by forming crystals of α solid solution extremely rich in A.  The process continuous with liquid getting richer in B and gradually moving down along the liquids line.  The α solid solution also getting richer in B, moving down along the solidus line.  When the solidus line crossed at T4 and with diffusion keeping pace with crystal growth the entire solid will be homogenous α solid solution.
• 13.
   Alloy 2:is the eutectic composition and remains liquid until the eutectic temperature is reached at point E.  Since this is also the solidus line, the liquid now undergoes the eutectic reaction, at constant temperature  The eutectic reaction may be written as
• 14.
   The leverrule is a tool used to determine weight percentages of each phase of equilibrium phase diagram.  The relative amounts of α and β in the eutectic mixture may be determined by lever rule