Small-angle grain limit

A small-angle grain boundary belongs to the group of two-dimensional lattice structural defects . That is, it is a special type of grain boundary that z. B. are constructed from a series of step dislocations .

The tilt angle θ is smaller than 15 °. It can be calculated from the Burgers vector  b and the distance  d of the step dislocation ( small-angle approximation ):

θ = b / d

If the accuracy is higher, this must be determined using an angle function:

sin (θ) = b / d

The energy content of a small-angle grain boundary falls with decreasing angle θ and is approx. 0.1 to 0.3  J / m².

Small angle grain boundaries arise z. B. by dislocation rearrangement in crystal recovery .

A tilting limit is made up of step dislocations, whereas a rotation limit is made up of screw dislocations .

literature

• Charles Kittel: Introduction to Solid State Physics , Oldenbourg, 11th edition 1996, ISBN 3-486-23596-6
• Günter Gottstein: Materials Science and Technology: Physical Basics , Springer Vieweg, 4th edition 2013, ISBN 978-3642366024