MICROSTRUCTURE STUDY OF CONSTITUENT PHASES IN 2024 SERIES Al ALLOYS

摘要

X-ray microanalysis,convergent beam electron diffraction（CBD）and selected area electrondiffraction（SAD）studies on the structures and compositions of the constituent phases in2024 series Al alloys have been conducted.Partial substitution of alloying elements is found tooccur in all the constituent phases,which cause small deviations from the stoichiometric com-positions reported in these ternary compounds.The dominant phase is α-Al₁₂（FeMn）₃Si whichhas a body center cubic crystal structure with the Im■ space group and a=1.25 nm.The nextdominant phase is Cu₂FeAl₇ which has a primitive tetragonal crystal structure with theP4/mnc space group and a=0.6336 nm,c=1.487 nm.The minor phase is α’-Al₁₂Fe₃Si hav-ing α primitive cubic crystal structure with the Pm■ space group and α=1.27 nm.