Abstract: The effect of yttrium and mischmetal composed of 50% Ce, 45% La (mass fraction) on the as cast structure of AZ91 alloy were investigated by optical microscope and electron microprober analysis. The experimental results show that the structure of AZ91 alloy is refined either by mischmetal or Y. The rod like typed compound is verified as (Ce,La)Al4 in AZ91 alloy with additional mischmetal; but a polyhedral compound is found and identified as YAl2 by EDX analysis in AZ91 alloy with additional Y. Both (Ce,La)Al4 and YAl2 have thermally stable property and do not dissolve into Mg matrix when solution treatment is carried out for 20 h at 420 ℃ followed by air quenching. The as cast structure of AZ91+RE(La,Ce,Y) alloy consists of three phases including Mg matrix, (Ce, La)Al4 (or YAl2) and Mg17Al12.
Effect of yttrium and mischmetal on as-cast structure of AZ91 alloy
Abstract:
The effect of yttrium and mischmetal composed of 50% Ce, 45% La (mass fraction) on the as cast structure of AZ91 alloy were investigated by optical microscope and electron microprober analysis. The experimental results show that the structure of AZ91 alloy is refined either by mischmetal or Y. The rod like typed compound is verified as (Ce, La) Al 4 in AZ91 alloy with additional mischmetal; but a polyhedral compound is found and identified as YAl 2 by EDX analysis in AZ91 alloy with additional Y. Both (Ce, La) Al 4 and YAl 2 have thermally stable property and do not dissolve into Mg matrix when solution treatment is carried out for 20?h at 420?℃ followed by air quenching. The as cast structure of AZ91+RE (La, Ce, Y) alloy consists of three phases including Mg matrix, (Ce, La) Al 4 (or YAl 2) and Mg 17 Al 12 . [