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Chapter VIII Micro-hardness studies…
Conclusions
1. The Vickers micro-hardness of pure and amino acids doped KDP crystals
is a load dependent quantity and the variation is prominent in low load
regime. Initially the Vickers micro-hardness decreased with increasing the
load very steeply and then for higher loads it decreases rather gradually
and became virtually independent of load. Thus the Indentation size effect
(ISE) was observed for both the pure and amino acid doped KDP crystals.
2. With increase in the concentration of a dopant (amino acids) the Vickers
micro-hardness also reduced at a considered load value in KDP crystals.
The Vickers micro-hardness decreased as amino acid doping level was
increased indicating that the KDP crystals became softer.
3. The ISE has been verified by using the Kick’s law. From the plots of log P
versus log d, the values of work hardening coefficient ‘n’ and the standard
hardness ‘a’ were obtained. The values of ‘n’ and ‘a’ were constant and
these values changed marginally with increased concentration of doping
in random manner. The variation of Vickers micro-hardness with load
agreed well with the nature obtained by the other workers on the (100)
faces of pure KDP crystals.
4. The values of the load independent hardness and the Newtonian
pressure (W) were higher in pure KDP crystals than the amino acids
doped KDP crystals. It was found that as the doping concentration of
amino acids increased the values of load independent hardness and
Newtonian pressure decreased. This further indicated that the doping of
amino acids had softened the KDP crystals slightly.
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