ALLOYS AND PHASE DIAGRAMS

Metals in actual commercial use are almost exclusively alloys, and not pure metals, since it is possible for the design engineer to realise an infinite variety of physical properties in the product by varying the metallic composition of the alloy. A homogeneous mixture of two or more metals or a metal and non-metal when fused together at a certain temperature forms a new metal after solidification, termed as an alloy. Alloys are normally harder than their components, less ductile and may have a much lower conductivity, whereas the highly purified single crystal of a metal is very soft and malleable, with high electrical conductivity. This is why pure metals are used only for specific applications. The alloy is usually more corrosion resistant and less affected by atmospheric conditions. The conductivity of an alloy varies with the degree of order of the alloy and the hardness varies with the particular heat treatment.

1.1 INTRODUCTION

1.2 DENDRITIC SOLIDIFICATION

1.3 ALLOTROPY OF METALS

1.4 Properties of alloys

1.5 Effect of grain size on properties of metals

1.6 Terms used in equilibrium diagrams

1.7 Solid solution

1.8 Types of solid solutions

            1.8.1 Substitutional solid solution

            1.8.2 Interstitial solid solution

1.9 Intermetallic compounds

1.10 CLASSIFICATION OF EQUILIBRIUM DIAGRAMS