Material Science Diffusion, Essay Example

“Diffusion in Material Science and Engineering”

Heat treatment involves the process of atomic diffusion.  The study of diffusion is used in material science due to the necessity of heat-treating materials in order to improve the structural properties.  The process of diffusion in material science and engineering involves a prediction using mathematical equations.  This process is important because materials are dependent on the transfer of mass within objects, whether solid, liquid or gas.  (Callister & Rethwisch, 123)

Atomically diffusion is the movement of atoms from one space to another using energy to break bonds in the other space and result in a conformational change.  There are different types of diffusion, two of which are dominant, Vacancy diffusion and interstitial diffusion. In addition, there are different factors that affect diffusion, such as diffusing species and temperature.  The current paper discusses the different types of diffusion and current research in materials science and engineering in regard to diffusion of materials.  (Callister & Rethwisch, 132)

Vacancy diffusion occurs when an atom from a normal lattice site interchanges to an adjacent vacant site.  This process is therefore dependent on the number of vacant spots of deformities that are present in the material.  (125) Interstitial diffusion is a process that involves the migration of atoms from an interstitial site to an adjacent site.  This type of process is mostly found occurring in the diffusion of impure small elements, such as carbon, hydrogen, oxygen and nitrogen.  (126)  In addition to the types of processes in material diffusion, there are specific factors that can affect diffusion, such as diffusing species and temperature.  The factor of diffusing species is dependent of the rate of diffusion. The type of diffusing species and the type of host material act as an influencing factor in the diffusion within the material.  The temperature also has an effect of the diffusion rate.  The temperature dependence is calculated through a diffusion coefficient, which is further dependent on activation energy. (132-133)

There are also two different states that exist in diffusion in materials science, referred to as “Steady-State” and “Nonsteady-State” Diffusion.  In the Steady-State diffusion, the diffusion occurs along with the concentration gradient.  The Nonsteady State diffusion occurs when there is a net accumulation of diffusion species.  In addition, diffusion processes are also used in surface treatments during machining operations. During operation, small grooves are formed in material that decrease fatigue life. Research has found that polishing methods increase fatigue life.  Case hardening is a type of technique that increases hardness and fatigue life in steel alloys.  Case hardening occurs through the atomic diffusion of carbon or nitrogen containing outer surface layers of the steel.  (263)  Current research has been geared towards the investigation of deep case hardening methods for use in engineering of bearings and gears.

A study conducted by investigated the oxygen diffusion technique specifically for deep case hardening of titanium and titanium alloys.  The authors explained the oxygen boost diffusion method and indicated the process consists of thermal oxidation in the air and vacuum diffusion. The researchers found that case hardening at 300 micrometers can be completed using the oxygen boost diffusion method.  In addition, the study found that titanium alloys treated with oxygen diffusion showed a significant improvement in the abrasive wear resistance.  (Dong, 303)

Diffusion is an important process in Materials Science and Engineering.  There are many uses and improving material is essential to the quality of products.  In addition, the development of methods, such as case hardening is also essential to quality.  For instance, case-hardened steel gears are commonly used in the automobile industry, particularly in transmissions.  (Callister & Rethwisch, 122) Case hardening methods, such as carbon treatments have been used in these processes; however, other methods, such as oxygen boost diffusion have been researched and proven to increase the hardening of materials.

Works Cited

Callister, W. and Rethwisch, D. Materials Science and Engineering An Introduction. 8^th Edition.  John Wiley & Sons, Inc. (2010). file:///C:/Users/owner/Downloads/Materials%20Science%20and%20Engineering%20by%20D.%20Callister.pdf

Dong, X.Y. Li, Oxygen boost diffusion for the deep-case hardening of titanium alloys,

Materials Science and Engineering: A, Volume 280, Issue 2, 31 March 2000, Pages 303-310, ISSN 0921-5093, http://dx.doi.org/10.1016/S0921-5093(99)00697-8
(http://www.sciencedirect.com/science/article/pii/S0921509399006978.