Alle Angebote für dieses Produkt
Über dieses Produkt
- KurzbeschreibungIn this study, the grain boundary-free surface line tension and grain boundary triple line tension were investigated on copper polycrystals, nanowires, and tricrystals through a thermodynamically correct approach which allows a direct and precise measurement of the line tension. The grain boundary-free surface line tension was determined by comparing the dihedral angle at the root of a flat and a curved grain boundary groove. A measurement of grain boundary triple line tension was achieved by the investigation of the force equilibrium at a triple junction as established by the inclination of the adjourning grain boundary grooves at the root of the triple junction. The experimental technique utilized atomic force microscopy (AFM) to scan the surface topography of grain boundary thermal grooves and triple junctions. <br>The mean value of the dihedral angle on a flat grain boundary groove in copper polycrystals was 161.8°, with a scatter of 2.3°. Assuming a surface energy of 1.75J/m2, the corresponding grain boundary energy was about 0.6J/m2. The grain boundary energies of a low angle grain boundary (9.4°<100>) and a special grain boundary (near &931;=17) were only 0.4J/m2. By comparing the dihedral angles at the root of a grain boundary groove on random grain boundaries and nanowires, the grain boundary-free surface line tension was derived to be (2.1±0.9)×10-8J/m on average. It was demonstrated that the normal shape of a thermal groove and a negative value of the grain boundary-free surface line tension can not be in equilibrium. <br>Copper tricrystals with specific orientations were fabricated by the vertical Bridgman technique. The triple line in a <111> tricrystal consisted of three high angle tilt grain boundaries. In a <100> tricrystal; there was a low angle tilt grain boundary, whereas a <110> tricrystal contained a low-&931; grain boundary. The grain boundary triple line energy in the <100>, <110>, <111> tricrystals was (5.3±1.9)×10-9J/m, (6.3±2.3)×10-9 J/m, (9.2±2.7)×10-9J/m, respectively. The magnitude is in agreement with the investigations of the contact triple line of liquid phases. It was found that, the grain boundary triple line energy will be reduced when there is a low energy boundary among the intersecting boundaries. <br>When the grain boundary-free surface line tension is taken into account for the Gibbs-Thompson relation, the equilibrium concentration of vacancies in the vicinity of a void at the grain boundary is strongly affected by the grain boundary-free surface line tension if the radius of the void approaches the order of ten nanometers
- AutorBingbing Zhao
- Ausgabe1. Auflage
- VerlagCuvillier Verlag
- Seiten118 Seiten
- Gewicht173 g
Meistverkauft in Sprache & Literatur
Dieser Artikel gehört nicht auf diese Seite.
Vielen Dank. Wir kümmern uns darum.