Role of A2 and A50 process on the oxide dispersion strengthened ferritic alloy fabricated by mechanical alloying

This study has investigated the effects of adding occasion of Stearic Acid (SA) on the characteristics of powder and properties of bulk with nominal composition of Fe–12Cr–2.5 W–0.4Ti–0.3Y2O3, which was fabricated by mechanical alloying and vacuum sintering. SA was milling with the powder mixture with 50 h (added before milling, A50) or 2 h (added after 48 h milling, A2). The resulted showed: SA could inhibit the agglomeration and retard the alloying process. Powders through A2 process achieved alloying with high powder yield, while the A50 powders presented alloying extent, and the yield of A0 powder presented low powder yield. SA added in A50 was almost dissolved into the matrix for the long milling duration, but SA added in A2 was mostly volatilized during heating. A2 bulk alloy was of better strength for the finer, more uniform grain and second phase and higher density than A50 bulk.

Research highlights
► Characteristics of powders and bulks were affected by Occasions of adding SA.
► A2 Powder was achieved alloying with high powder yield.
► A50 powder was of low alloying extent, and A0 powder was of low powder yield.
► SA in A50 was dissolved into the matrix. SA in A2 was volatilized during heating.
► A2 bulk was of finer, more uniform grains and second phase and higher density.