In order to increase the wear resistance of the nib, the small particles of osmium and iridium raw ore in the free state of nature were welded on the nib in the early stage of foreign countries. But the limitation and output and quality, with the development of metallurgical technology, osmium, iridium and other precious metals to join other metals into metal particles, because the alloy contains iridium, so called "iridium grain".
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