Chapter 10, Problem 10.61P

Interpretation Introduction

(a)

Interpretation:

The composition of each of the phases in the given alloy of Nb-W at ${2800}^{\circ }\text{C}$ is to be determined, if possible.

Concept Introduction:

On the temperature-composition graph of a ceramic, the curve above which the ceramic exist in the liquid phase is the liquidus curve. The temperature at this curve is the maximum temperature at which the crystals in the ceramic can coexist with its melt in the thermodynamic equilibrium.

Solidus curve is the locus of the temperature on the temperature composition graph of a ceramic, beyond which the ceramic is completely in solid phase.

Between the solidus and liquidus curve, the ceramic exits in a slurry form in which there is both crystals as well as ceramic melt.

Solidus temperature is always less than or equal to the liquidus temperature.

Interpretation Introduction

(b)

Interpretation:

The amount of each of the phases in the given alloy of Nb-W at ${2800}^{\circ }\text{C}$ is to be determined, if possible.

Concept Introduction:

A matter can exist in different physical forms such as sold, liquid, gas, and plasma. These distinct physical forms are known as a Phase.

A phase has uniform physical and chemical properties and is bounded by a surface due to which two phases can be mechanically separated from each other.

Amount of each phase in wt% is calculated using lever rule. At a particular temperature and ceramic composition, a tie line is drawn on the phase diagram of the ceramic between the solidus and liquidus curve. Then the portion of the lever opposite to the phase whose amount is to be calculated is considered in the formula used as:

  $\text{Phase wt\%}=\frac{\text{opposite arm of lever}}{\text{total length of the tie line}}\times 100$ ...... (1)