Prakt. Met. Sonderband 38 (2006) 243 
B and Co/Fe binder hardmetal H. The nitrided hardmetals with Ni-binder show a more 
compact and homogeneous surface layer compared to the samples with Co-binder. 
ment of 
or in the 
li-binder 
im. This 
metals, 
s place. 
etals is 
4 times 
. This is 
the Fe- 
sintering 
int, thus 
ally the Fig. 2. SEM micrographs of the cross-section of nitrided samples with different binder phases. (a) Sample 
etals is B (Co-binder), (b) sample D (Ni-binder), (c) sample F (Ni/Co-binder), (d) sample H (Co/Fe-binder), d) sample 
J (Ni/Fe-binder) 
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d phases 
ding to a Fig. 3. ; SEM micrographs of the cross-section of nitrided samples with different binder phases. (a) Sample 
B (Co-binder), (b) sample D (Ni-binder), (c) sample F (Ni/Co-binder), (d) sample H (Co/Fe-binder), (e) 
sample J (Ni/Fe-binder) 
3.2.2 Hard phases in the nitrided hardmetal 
od oo WC phase: The WC grains in the Co-binder hardmetals appear sharp-edged whereas in 
d by the the Ni-binder the WC tends to exhibit more rounded edges. The mixed Co-Ni binder 
se The produced a mixture of both types of WC. As for the Fe-containing hardmetals, the round- 
-ain size edged WC grains only appear in case of Ni-Fe binder. This could lead to improved 
een the toughness and reduced sensitivity to cracking, in contrast to the sharp edges, which could 
by the form local tensile stress concentrations on loading of the hardmetal, thus promoting crack 
rdmatal initiation and propagation [15]. The surface of the round-edged WC grains presents