[Wien] Calculating hardness - reg

[Peter Blaha]

You overestimate my abilities. I've never calculated hardness ....

PS: I know from literature that some people have done this in various 
ways, although I have some doubts that it can be relevant for a "real 
material", where defects, precipitates and dislocations play a major 
role (at least for metals) in "hardness" and the same steel before/after 
hardening is very different (and has not much to do with the Vickers 
hardness of pure Fe). But it might be different for covalent hard 
materials ...


On 02/17/2015 11:24 AM, Murugan Sundareswari wrote:
> Dear Professor Blaha,
>
> Please Clarify the following Doubts
>
> There are range of Vicker's hardness formula for calculating the
> hardness of the crystal system.
> For example,
>                  (i)    Hv = ((1-2*σ*)E) / (6*(1+*σ*)), where
> σ=(3B-2G)/(6B+2G)
>                  (ii)   Hv = (2*(K^2*G)^0.585)-3, where K=G/B and
>                  (iii)  Hv = (0.92*K^1.137*G^0.708), where K=G/B
> If we proceed with these hardness formula we are getting different
> hardness value. Please guide us that which is the best Vicker's hardness
> formula for calculating the hardness of the cubic crystal system.
>                                               Thanking you.
>
>
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-- 

                                       P.Blaha
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Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
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