Ọla ọla kọpa na-acha ọcha (cupronickel), alloy ọla kọpa nwere ụdị. Ọ na-acha ọcha ọlaọcha, n'ihi ya, a na-akpọ ya ọla ọcha. E kewara ya ụzọ abụọ: cupronickel nkịtị na cupronickel dị mgbagwoju anya. Cupronickel nkịtị bụ ọla kọpa-nickel alloy, nke a na-akpọkwa "De Yin" ma ọ bụ "Yang Bai Tong" ...
GỤKWUO