マグネシウム合金の腐蝕(第8報)

Abstract

An addition of chromium to magnesium alloys containing aluminium was tried by preparing a mother alloy with aluminium, and corrosion test was carried out in N/10 NaCl solution. It is shown that the addition of chromium for magnesium alloys containing aluminium, but not manganese, is markedly effective as that of manganese to reduce the rate of corrosion (Mg-Al-Zn-Cr alloys prepared with mother alloy Al-Zn-Cr containing 10-25% Cr, Table 2 and Fig. 2), but for magnesium alloys containing both aluminium and manganese it has no effect (Mg-Al-Mn-Cr alloys prepared with mother alloy Al-Mn-Cr containing 5-15% Cr, Table 1 and Fig. 1), or it is slightly effective (Mg-Al-Zn-Mn-Cr alloys containing more than 0.2% Mn which were prepared with mother alloy Al-Zn-Mn-Cr containing 5-25% Cr, Table 3 and Fig. 3). All alloys thus prepared, however, lost a large amount of chromium in melting, and found to contain only 0.01-0.03% Cr by analysis, irrespective of chromium content in mother alloys used and hence whether the beneficial effect is brought about by chromium addition or not is somewhat obscure. The effect of Sn, Cd, Pb, Ca, Sb, Bi, Si, Ce, Se, Ba, Mo, V or Zr added to Electron AZG alloy, containing small amount of chromium as above, has also been studied. The results obtained are shown in Fig. 4 and in Table 5 and 6.