Premium
Microhardness studies of nanocrystalline calcium tungstate
Author(s) -
Anandakumar V. M.,
Khadar M. Abdul
Publication year - 2008
Publication title -
crystal research and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.377
H-Index - 64
eISSN - 1521-4079
pISSN - 0232-1300
DOI - 10.1002/crat.200710987
Subject(s) - indentation hardness , nanocrystalline material , materials science , grain size , indentation , annealing (glass) , transmission electron microscopy , nanocrystal , tungstate , scanning electron microscope , vickers hardness test , composite material , mineralogy , metallurgy , microstructure , nanotechnology , chemistry
Nanocrystals of calcium tungstate (CaWO 4 ) of three different grain sizes were synthesized through chemical precipitation technique and the grain sizes and crystal structure were determined using the broadening of X‐ray diffraction patterns and transmission electron microscopy. The microhardness of compacted pellets of nanocrystalline calcium tungstate (CaWO 4 ) with different grain sizes were measured using a Vickers microhardness tester for various applied loads ranging from 0.049 N to 1.96 N. The values of microhardness showed significant reverse indentation size effect at low indentation loads. The microhardness data obtained for samples of different grain sizes showed grain size dependent strengthening obeying normal Hall‐Petch relation. The dependence of compacting pressure and annealing temperature on microhardness of the nanostructured sample with grain size of 13 nm were also studied. The samples showed significant increase in microhardness as the compacting pressure and annealing time were increased. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)