Discontinuous precipitation of solution-treated Nb-40Zr-10Ti superconducting alloy

The behavior of the discontinuous precipitation of solution-treated Nb-40Zr-10Ti alloy was investigated by means of optical and electron microscopy and hardness measurements.The results are as follows:(1) Several types of discontinuous precipitation are observed morphologically.(2) The 〈1\bar10〉 direction of β′ is nearly parallel to the 〈1\bar10〉 direction of the β″ phase.(3) The rate of the β→β′+β″ reaction (lamellar type) of the specimen aged at 620° to 800°C decreases with increasing ageing temperature.(4) The interlamellar spacing of the β′+β″ structure aged at 620° to 825°C increases linearly with the ageing temperature.(5) The hardness (HMV) in the discontinuous precipitated region (about 200) is lower than that of the continuous precipitated region (maximum: 350).