Register to reply

Grain size and grain boundary diffusion

by krahl
Tags: boundary, diffusion, grain, size
Share this thread:
krahl
#1
Mar8-12, 04:54 PM
P: 1
Hi all,

I was wondering if anyone knows of any literature that explains why larger grains "absorb" smaller grains during cross-boundary diffusion in solid state diffusion. I read a book that explains it analogously in terms of pressure differences and boundary tension but I'm not quite happy with that explanation.

Thanks
Phys.Org News Partner Engineering news on Phys.org
Hoverbike drone project for air transport takes off
Student develops filter for clean water around the world
Developing the next evolution in underwater communication
qazxswedc
#2
Mar11-12, 10:16 AM
P: 2
Assuming the concentration of solute is constant in the solid solution, the growing of one grain is at the expense of the other grain. This is to reduce the surface energy of the whole system because in equilibrium, a system will choose to 'react' in a way to minimize its free energy. The total interfacial area of large, fewer particles will be smaller than total interfacial area in the system with many small particles. Note that interfacial energy will increase the free energy of the system hence it is preferable to have smallest interfacial energy as possible.
streeters
#3
Apr9-12, 06:14 AM
P: 221
Quote Quote by qazxswedc View Post
Assuming the concentration of solute is constant in the solid solution, the growing of one grain is at the expense of the other grain. This is to reduce the surface energy of the whole system because in equilibrium, a system will choose to 'react' in a way to minimize its free energy. The total interfacial area of large, fewer particles will be smaller than total interfacial area in the system with many small particles. Note that interfacial energy will increase the free energy of the system hence it is preferable to have smallest interfacial energy as possible.
Yeah, minimising the total free energy is what drives this.

Look at Ostwald Ripening for literature on this.


Register to reply

Related Discussions
Grain size Materials & Chemical Engineering 1
Twin Grain Boundary and Symmetric Tilt Grain boundary. Atomic, Solid State, Comp. Physics 1
Average grain diameter at 310MPa from 2 known yield/grain values Engineering, Comp Sci, & Technology Homework 2
(ceramics) grain size Engineering, Comp Sci, & Technology Homework 2
About Grain Size Hardening Mechanical Engineering 12