ISSN:
1551-2916
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
Some K2O-Nb2O5-GeO2 glasses are prepared, and their crystallization behaviors are examined. 25K2O·25Nb2O5·50GeO2 glass with the glass transition temperature Tg= 622°3C and crystallization onset temperature Tx= 668°3C shows a prominent nanocrystallization. The crystalline phase is K3,8Nb5Ge3O20,4 with an orthorhombic structure. The sizes of crystals in the crystallized glasses heat-treated at 630° and 720°3C for 1 h are °10 and 20–30 nm, respectively, and the crystallized glasses obtained by heat treatments at 620°-850°3C for 1 h maintain good transparency. The density of crystallized glasses increases gradually with increasing heat-treatment temperature, and the volume fraction of crystals in the sample heat-treated at 630°3C for 1 h is estimated to be ∼35%. The usual Vickers hardness and Martens hardness (estimated by nanoindentation) of 25K2O·25Nb2O5·50GeO2 glass change steeply by heat treatment at Tg, i.e., at around 35% volume fraction of nanocrystals. The present study demonstrates that the composite of nanocrystals and the glassy phase has a strong resistance against deformation during Vickers indenter loading in crystallized glasses.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1551-2916.2004.00113.x
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