Recrystallization Theoretical & Practical Aspects - Materials Science ...

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Intro <strong>Recrystallization</strong> Lab 1 Grain Boundaries Lab 1 - Expected Results • Hardness: before recrystallization, the hardness should increase with increasing strain (hint - relate this to what you know about stress-strain behavior in metals). • After recrystallization, the grain size will increase with increasing temperature, but decrease with increasing prior strain. • Also after recrystallization, the hardness will increase with decreasing grain size (Hall-Petch effect) in the recrystallized areas. • Note: a critical part of the Lab is to obtain high quality images of the grain structure so that you can measure grain size. The metallography involved requires skill and effort. Also, computer-based submissions are required (Word, or LaTex). 24
Intro <strong>Recrystallization</strong> Lab 1 Grain Boundaries What is a Grain Boundary? • Grain boundaries control the process of recrystallization. This suggests that it is worth knowing something about the structure and properties of boundaries. • Regular atomic packing disrupted at the boundary by the change in lattice directions. • In most crystalline solids, a grain boundary is very thin (one/two atoms). • Disorder (broken bonds) unavoidable for geometrical reasons; therefore large excess free energy. This interfacial energy is analogous to the surface tension in a soap bubble (and many investigations on grain growth have been made with soap froths). 25
Page 1 and 2: Intro Recrystallization Lab 1 Grain
Page 9 and 10: Grain size as a function of prior d
Page 13 and 14: Intro Recrystallization Lab 1 Tempe
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Recrystallization Theoretical & Practical Aspects - Materials Science ...

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