Meaning
High-temperature deformation mechanisms involve adjacent crystalline grains displacing relative to one another along common interfaces. The phenomenon of grain boundary sliding contributes significantly to plastic creep deformation in metals and alloys under sustained stress. The mechanism operates in copper connectors, busbars, and structural metallic components exposed to elevated temperatures.
Scope limits govern intergranular displacement without covering intragranular dislocation glide.
Deformation Kinetics
Thermal activation enables atoms along grain boundaries to shear under applied stress. High temperature forces grain boundary sliding to scale inverse to grain size due to elevated boundary area. Impurities located at grain boundaries alter sliding resistance and cavity nucleation rates.
Creep deformation progresses rapidly when temperatures exceed half the absolute melting point. Microstructural grain coarsening mitigates sliding displacement rates under load.
Structural Impact
Continuous sliding along interfaces generates micro-voids at grain triple junctions. Cavity formation resulting from grain boundary sliding leads to intergranular cracking and premature structural failure of electrical contacts. Stress relaxation in bolted copper connectors reduces contact pressure over extended operating periods.
Alloy additions that pin boundaries mitigate creep rates.
Material Control
Heat treatment procedures coarsen grain structure to reduce total boundary area in high-temperature applications. Precipitate pinning agents block boundary motion and suppress grain boundary sliding. Mechanical testing under elevated temperature quantifies long-term creep rupture resistance.
