as far as exotic metals ? Google doesn't show anything in Vietnam, again you may have better luck selling in China.
-----no,the scrap jet engines are all from the US aircraft during Vietnam war,so not exotic metals.as to sell it to Chinese scrap metal recycling company,i also have thinken over it ,because almost no scrap jet engines are sale in China,so Chinese scrap metal recycling company all do not familar to it ,even the Chinese scrap metal recycling company want to buy it,they also can not offer reasonable price,so i had better to contact scrap metal recycling company at developed countries.