Ductility vs Malleability
In common language, ductility refers to the ability to be deformed without losing toughness; that is pliable, but not brittle. Malleable means the ability to be hammered or pressed into shape without breaking or cracking. These properties are of great importance in selecting materials for building and manufacturing products.
Ductility and malleability are two aspects of the plasticity of solid materials. In metals, ductility and malleability are very high due to their ability to sustain large amounts of plastic deformations within the crystal structure. Platinum is the most ductile material, and gold is the most malleable material.
Ductility is the ability of a solid material to undergo tensile stress. This property of a solid material can be measured and describes the extent to which the solid material can be plastically deformed without fracture. It is often depicted by the ability of the solid to stretch into a wire when pulled at the ends.
The mechanical property of ductility is quantified by the fracture strain, which is the strain at which the material fractures when increasing tensile stresses are applied along a single axis. The reduction of the area from the initial point to the fracture during the test can also be considered as a measure.
Ductility is a property specially looked for in metals. Metals have a very high ductility. Therefore, metals can be easily manipulated compared to other solid materials.
Malleability is the ability of solid materials to undergo compressive stress. Metals are highly malleable compared to non-metal materials. Therefore, metals can be shaped using forming methods such as forging, rolling, extrusion and indenting.
Since gold is highly malleable they can be forged into very thin foils, sometimes only few atoms thick.
What is the difference between Ductility and Malleability?
• Ductility and malleability are two aspects of the plastic deformation process of solid materials. Since metals have a crystal structure and free electrons to allow large amounts of dislocations, they are both highly malleable and ductile.
• Ductility of a solid material is the ability to undergo tensile stress without fracture or damage; simply the ability to draw a material into a wire by pulling at the ends
• Malleability of a material is the ability to undergo compressive stress without fracture or damage; simply, it is the ability to be hammered or pushed into thin sheets without breaking.
• In most cases, ductility and malleability are coexisting. Silver and gold are highly malleable and ductile. But in some cases ductility can be higher while malleability is low or vice versa. For example, Lead and cast iron are highly malleable while having lower ductility.