Chapter 10, Problem 10.76P

Interpretation Introduction

(a)

Interpretation:

The liquidus temperature for Nb-W alloy is to be determined.

Concept Introduction:

On the temperature-time graph of an alloy, the first point where the deflection or the change in the slope of the cooling curve is seen is the liquidus temperature of that alloy. This is where the first crystals in the alloy can coexist with its melt in the thermodynamic equilibrium.

Interpretation Introduction

(b)

Interpretation:

The solidus temperature for Nb-W alloy is to be determined.

Concept Introduction:

On the temperature-time graph of an alloy, the second point where the deflection or the change in the slope of the cooling curve is seen is the solidus temperature of that alloy at which the crystals in the alloy can coexist with its last liquid in the thermodynamic equilibrium.

Interpretation Introduction

(c)

Interpretation:

The freezing range for Nb-W alloy is to be determined.

Concept Introduction:

Freezing range for an alloy is the difference of the liquidus and the solidus temperature of an alloy. In this range, the alloy melt starts to crystallize at liquidus temperature and solidifies when reaches solidus temperature.

Interpretation Introduction

(d)

Interpretation:

The pouring temperature of the Nb-W alloy is to be determined.

Concept Introduction:

The temperature at which the material is poured into the cast and then allowed to cool thereafter is known as the pouring temperature.

On a cooling curve (temperature-time), pouring temperature is the starting point temperature.

Interpretation Introduction

(e)

Interpretation:

The superheat for the given Nb-W alloy is to be determined.

Concept Introduction:

Superheat for a material is defined as the difference in the pouring temperature and the liquidus temperature of the casting material.

Interpretation Introduction

(f)

Interpretation:

The local solidification time for the given Nb-W alloy is to be determined.

Concept Introduction:

The time needed to only remove the latent heat of fusion in the casting at a particular location is known as the local solidification time. It is measured from the point of the start of the solidification until the end of it.

Interpretation Introduction

(g)

Interpretation:

The total solidification time for the given Nb-W alloy is to be determined.

Concept Introduction:

The time needed to remove the latent heat of fusion as well as the specific heat of the liquid in the casting at a particular location is known as the total solidification time. It is measured from the time of pouring until the end of the solidification.

Interpretation Introduction

(h)

Interpretation:

The composition of the given Nb-W alloy is to be determined.

Concept Introduction:

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

Solidus curve is the locus of the temperature on the temperature composition graph of an alloy, beyond which the alloy is completely in solid phase. The temperature at this curve is minimum, known as solidus temperature at which the crystals in the alloy can coexist with its melt in the thermodynamic equilibrium.