1. The Preceding scdre tactics are really intended only t o indicate that published creep values for a given material can vary considerably with l i t t l e or no apparent reason. But such information i s particularly important for MFHPs and TEC i n systems with -1800 K emitters. And for these applications, satisfactory materials are few as the Cree -strength curves of Fig. 10 i11ustrate 85.
2. Like Ti, refractory metals Z r and Hf, also i n periodic roup IVA, undergo solio-phase transitions 43-4%,84. i n contrast group VA Nb and Ta as well as group VIA MO and W exhibit no solidphase changes.