What is a dispersion strengthened material?

Dispersion strengthening refers to the process of increasing the toughness of a metallic object by introducing a second phase through the addition of an alloying element. This is done to increase the strength of metallic objects subject to corrosion.

What is the main difference between dispersion strengthening and precipitation hardening?

The two differences are: 1) the hardening/strengthening effect is not retained at elevated temperatures for precipitation hardening–however, it is retained for dispersion strengthening; and 2) the strength is developed by a heat treatment for precipitation hardening–such is not the case for dispersion strengthening.

Which of the following particles can be used for oxide dispersion strengthened alloys?

Oxide dispersion strengthened alloys (ODS alloys) typically consist of a high temperature metal matrix – such as iron aluminide, iron chromium, iron-chromium-aluminium, nickel chromium or nickel aluminide – with small (5-50nm) oxide particles of alumina (Al 2O 3) or yttria (Y 2O 3) dispersed within it.

What is the full form of ODS in engineering materials?

Oxide dispersion-strengthened (ODS) variants improve high-temperature resistance properties and are designed to add strength (e.g., creep rupture, tensile, and fatigue strength) while retaining other good properties. ODS materials have been found to be stable to irradiation of temperatures up to 800 °C.

What are the 4 strengthening mechanisms of metals?

In general, the solid solution strengthening depends on the concentration of the solute atoms, shear modulus of the solute atoms, size of solute atoms, valency of solute atoms (for ionic materials), and the symmetry of the solute stress field.

What is age hardening?

Age hardening, also known as precipitation hardening, is a type of heat treatment that is used to impart strength to metals and their alloys. The metal is aged by either heating it or keeping it stored at lower temperatures so that precipitates are formed. The process of age hardening was discovered by Alfred Wilm.

What two factors must be present for precipitation hardening to occur?

Precipitation hardening relies on changes in solid solubility with temperature to produce fine particles of an impurity phase, which impede the movement of dislocations, or defects in a crystal’s lattice. Since dislocations are often the dominant carriers of plasticity, this serves to harden the material.

What is a major advantage of solid solution strengthened alloys?

Solid solution strengthening is the effect of alloying a metal while remaining within the single phase region of the phase diagram. The local strain of the alloy atoms in the host matrix provide resistance for dislocation movement–increasing the strength of the alloy.

Which method is used for producing ODS alloy?

Oxide dispersion strengthened (ODS) alloys are produced by the mechanical alloying of powders. The powder constituents can be in the elemental, intermetallic or pre-alloyed state. The metal and oxide (i.e. Yttria) powders are blended and mechanically alloyed using a ball mill.

What is ODS alloy explain how ODS alloys are produced and discuss the properties and applications?

Oxide dispersion strengthened (ODS) alloys, usually produced by a dispersion of nano-sized rare earth metal oxides such as yttrium oxides, are thriving structural materials for high temperature applications because they exhibit good mechanical properties such as tensile and creep strength at high temperatures1,2,3,4,5.

Does annealing strengthen metal?

Annealing. Annealing is frequently used to soften metals including iron, steel, copper, brass and silver. Annealing alters the physical and chemical properties of the metal to increase ductility and reduce hardness. This facilitates shaping, stamping or forming processes, and allows the metal to be cut more easily.

How is metal strengthened?

Gently heating a hardened metal and allowing it to cool slowly will produce a metal that is still hard but also less brittle. Because plastic deformation results from the movement of dislocations, metals can be strengthened by preventing this motion. When a metal is bent or shaped, dislocations are generated and move.

When do you use dispersion strengthening what happens?

This is done to increase the strength of metallic objects subject to corrosion. Dispersion strengthening occurs when a significant concentration of a second alloying metal is added to another core metal, which results in exceeding the base material’s solubility limit. Ultimately, a second phase is formed due to the generation of a two-phase alloy.

What are oxide dispersion strengthened alloys used for?

Oxide dispersion strengthened alloys (ODS) consist of a metal matrix with small oxide particles dispersed within it. They are used for high temperature turbine blades and heat exchanger tubing. Alloys of nickel are the most common but work is being done on iron aluminum alloys.

How is Oxide Dispersion strengthening related to creep?

Oxide dispersion strengthening is based on incoherency of the oxide particles within the lattice of the material. The oxide particles decrease movement of dislocations within the material and in turn prevent creep. Since the oxide particles are incoherent, dislocations can only overcome the particles by climb.

Which is more effective, precipitation strengthening or dispersion strengthening?

The effect of dispersion strengthening is effective at high temperatures whereas precipitation strengthening from heat treatments are typically limited to temperatures much lower than the melting temperature of the material. One common type of dispersion strengthening is oxide dispersion strengthening .