invention only specimens nos 9 10 and 14 show small oxidation increments and all the remaining reference alloy specimens show large oxidation increments in view of this fact it is apparent that the alloys of the present invention have excellent corrosion resistance at high temperatures in an atmosphere of a low oxidizing potential in measuring oxidation increments oxide films spalled off and dispersed were not collected for weighing the values shown in table 6 are therefore somewhat lower than the actual oxidation increments as a result of an examination by a scanning type electron microscope of the shape of oxide films formed on the surfaces of alloy specimens in said high temperature corrosion test as shown in table 6 while the alloy specimens nos 1 to 6 of the present invention showed whisker crystals in only a slight amount many whisker crystals grew in the reference alloy specimens outside the scope of the present invention particularly in specimens nos 11 17 18 and 19 fig7 is a microphotograph photograph showing the shape of oxides formed on the surface of reference alloy specimen no 11 taken by a scanning type electron miscroscope from which many whisker crystals are observed it was also noted that said whisker crystals did not grow on the alloy specimens placed near the helium gas inlet of the retort but.