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Digitale Medien

The influence of quenched-in crystals on the thermal stability of partially amorphous Zr76Ni24 alloy (1984)

Toloui, B. ; Gregan, G. ; Scott, M. G.

Springer

Journal of materials science 19 (1984), S. 4007-4013

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Details

ISSN: 1573-4803

Quelle: Springer Online Journal Archives 1860-2000

Thema: Maschinenbau

Notizen: Abstract Fully glassy and part-crystalline ribbons were prepared by melt spinning the Zr76Ni24 melt at different rates. X-ray and STEM studies confirmed that the quenched-in crystals are α-zirconium. It is shown that these pre-existing crystals do not grow during annealing treatment nor do they act as heterogeneous nucleation sites, and remain inertly during the crystallization of the surrounding amorphous matrix. Crystallization studies showed that the existence of a fraction of crystallinity within the glassy matrix increases the stability of the matrix against further crystallization. Possible explanations for this behaviour are presented.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00980764

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Digitale Medien

Temperature dependence of surface crystallization in bimorphic PET fibers (1982)

Durning, C. J. ; Scott, M. G. ; Weigmann, H.-D.

New York, NY [u.a.] : Wiley-Blackwell

Journal of Applied Polymer Science 27 (1982), S. 3597-3620

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ISSN: 0021-8995

Schlagwort(e): Chemistry ; Polymer and Materials Science

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Maschinenbau , Physik

Notizen: Open-bath, organic liquid treatments may be used to produce high surface area PET fibers through the action of liquid solvent-induced crystallization (SINC). It has been found that as the treatment bath temperature is increased, surface modification suddenly disappears. For a particular treatment method this occurs at a reproducible temperature, well below the liquid boiling point. A qualitative understanding of the mechanism of surface cavitation during liquid SINC is developed based on current descriptions of the component processes involved. These processes are: the glass-rubber transition, diffusion through rubbery and glassy polymer, and polymer-diluent crystallization. Although calculations of the threshold concentration for swelling support this conceptual framework, the absence of surface cavitation at higher treatment bath temperatures is not explained by it and is therefore attributed to an intervening phenomenon. Analysis of penetration depth data together with surface microscopy suggest the formation of a smooth surface layer interfering with normally observed cavitation at elevated temperatures. Manipulation of the extent of vapor precontact shows that vapor SINC prior to liquid exposure is most likely responsible for the smooth layer.

Zusätzliches Material: 21 Ill.