Phase Diagrams

Question 1

What is a phase diagram

Answer 1

A phase diagram is a map which shows the relationship between phases in equilibrium in a system at various temperatures, pressures, and compositions.

Question 2

What is a phase

Answer 2

A phase is a physically-distinct, chemically-homogeneous and
mechanically-separable region of a system.

Question 3

What is a component

Answer 3

The components of a system refer to the chemical species that comprise the system. They may be elements, ions or compounds.

Question 4

explain the phase rule

Answer 4

The phase rule determines the number of independent variables (i.e. degrees of freedom (F)) needed to describe the system at any given point.
It is also known as Gibb’s Equation:
F=C(number of components)-P(number of phases)+2

Question 5

what happens at the triple point

Answer 5

There are no degrees of freedom. Therefore, in this situation, neither temperature or pressure may be varied without altering one or two of the phases

Question 6

What is the liquidus

Answer 6

The phase boundary between the liquid and the two phase region is called the liquidus.

Question 7

What is the solidus

Answer 7

The boundary between the solid and the two phase region is called the solidus.

Question 8

Describe a euctectic phase diagram

Answer 8

When the solid solubility is limited and the melting points of the components are not vastly different

Question 9

describe the solvus

Answer 9

When the solid solubility is limited, it is indicated by the phase boundary called the solvus.