On the formation and interaction of small metal particles
Abstract
The formation, growth and interaction of small metal particles (10–100 nm) produced by gas evaporation has been studied. Single metal atoms diffuse radially out from the evaporation source until they condense at a temperature of roughly 0.35–0.40 Tm, where Tm is the absolute melting temperature. The particles then grow, mainly by coalescence. The final size of the particles is determined by evaporation temperature and gas pressure.
When the particles interact strong adhesion strain fields are created. These strain fields cause plastic deformation (twins) in many metals, but no twins were observed in aluminium and iron.
Résumé
Nous avons étudié la formation, la croissance et l'interaction de petites particules métalliques (10–100 nm) produites par évaporation. Les atomes métalliques diffusent individuellement et radialement à partir de la source d'évaporation et se condensent à une température de l'ordre de 0,35 à 0,40 Tm, oúTm est la température absolue de fusion. Les particules croissent ensuite, essentiellement par coalescence. La taille finale des particules est déterminée par la température d'évaporation et la pression du gaz.
Lorsque les particules interagissent, il se produit d'importants champs de déformation d'athaction. Ces champs de déformation produisent une déformation plastique de nombreux métaux (macles), mais nous n'avons pas observé de macle dans l'aluminium ni dans le fer.
Zusammenfassung
Bildung, Wachstum und gegenseitige Wechselwirkung kleiner, durch Verdampfung im Gas erzeugter Metallpartikel wurde untersucht. Einzelne Metallatome diffundieren radial aus einer Verdampfungsquelle, bis sie bei einer Temperatur von etwa (0,35 - 0,40) Tm (Tm = absolute Schmelztemperatur) kondensieren. Die Partikel wachsen anschlieβend, überwiegend durch Zusammenlagern. Die Endgröβe der Partikel ist bestimmt von Verdampfungstemperatur und Gasdruck.
Bei der Wechselwirkung zwischen Partikeln entstehen starke Adhäsions-Verzerrungsfelder. Diese Verzerrungen bedingen plastische Verformung (Zwillinge) in vielen Metallen; jedoch wurden keine Zwillinge beobachtet in Aluminium und in Eisen.
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