UNIT VII
PHASE RULE
FILL IN THE BLANKS
1. A system which is uniform throughout in its physical and chemical properties is called homogeneous system.
2. Any homogeneous ,physically distinct and mechanically separable portion of a heterogeneous system in equilibrium is called Phase
3. The smallest number of independent constituents by means of which the composition of each phase can be expressed in terms of chemical equation is called components.
4. If F = 0 , the system is called Invariant.
5. The phase rule for one component system is given by F = 3 – P
6. The point which refers to the temperature and pressure where a liquid and its vapor become identical is called Critical temperature.
7. Triple point is the condition of temperature and pressure under which three phases of a substance co-exist in equilibrium.
8. The crossing of two-phase equilibrium curve in a phase diagram is termed as transition
9. A plot which shows the condition of pressure and temperature under which two or more physical states exist together in a state of dynamic equilibrium is a Phase Diagram
10. The sublimation curve of ice cane be lowered by increase in Pressure
11. If the pressure is kept constant, the phase diagram is called isobaric
12. The solid-liquid system with the gas phase absent is called a condensed or reduced system
13. The state of super cooled or super saturated solution in which the phase, which is normally stable under the given condition, does not from is called metastable state.
14. A triple point is Invarient or Non-varient
15. The eutectic composition of lead-silver system is 2.4% silver and 97.6% lead.
16. The number of degrees of freedom for an invariant system is Zero
17. The composition which is preferred in order to get a two metal low melting alloy is Eutectic Point
18. Rose metal is used for making fire-alarms, fuse wires and in automatic sprinklers
19. The curve above which the system consists of only liquid only is Liquidus or freezing curves
20. The curve below which the system consists of only solid phase is solidus or melting curves
21. For the construction of the phase diagram of a binary alloy system Thermal analysis method is used.
22. Iron-carbon alloys containing up to 1.7% of carbon are classified as Steels
23. The percentage of carbon present in cast iron is greater than 1.7%
24. The eutectoid of ferrite and cementite formed by the decomposition of austenite is Prearlite
25. The miscibility or solubility of carbon in iron depends on the crystal structure or lattice structure of iron
26. Tempering is carried out about 200 0 C to make hard steel resistant to abrasion.
27. Fe-C phase diagram depicts the various phase transformations occurring, while cooling liquid alloys having different carbon contents.
