Effect of impurity levels on precipitation behavior in the low-activation V–4Cr–4Ti alloys

The precipitation behavior of the V–4Cr–4Ti model alloys with different oxygen and nitrogen levels has been investigated. Fine and large precipitates were observed. Large precipitates were formed during the initial fabrication process and were stable to 1373 K. Fine precipitates were formed at 973 K and disappeared at 1373 K. The dependence of the hardness and microstructure on oxygen and nitrogen levels at various annealing temperatures showed that most of nitrogen impurities are included into the large precipitates, and oxygen impurities are partitioned into the large, fine precipitates and the matrix.