compresslw resldual stresses. Laser surface m odltlcatlon
followlng the EDM of dle steel and cemented carblde
workplece materlals has also been reported [20. 211.
Here, mettlng In whole or part, of the orlglnal recast
structure Is employed to provlde a new, apparently defect
free surface. Unfortunately. such processes are addttlonal
to the orlglnal EDM operatlon and therefore add cost and
tlme. An attematlve solutlon Is the controlled alloylng of
the rmrkplece surface durlng sparklng wlth metal powders
dlspersed In the dlelectrlc, In a slmllar manner to that
detalled previously, to produce a pollshed surface
appearance, or the use of partlally slntered electrodes,
typlcally made from refractory metal powders and a blnder.
Netther Is mutually exclusive and thelr slmuttaneous use
owers the prospect for harder more war reslstant surfaces
wlth low roughness and mlnlmal cracklng. The use of the
recast structure In a modMed form to promote the jolnlng
of materlals Is also a posslblllty. Flgure 1 shows
schematlcs of both arrangements.
2 SURFACE ALLOYING
Perhaps not surprlslngly, publlcatlons detalllng the