Characterisation of High Temperature Phase Stability and Evaluation of Metallurgical Compatibility with SS 304L, of Indigenously Developed Alternate Shielding Material Ferro- Boron for Fast Reactor Applications

The high temperature phase stability and metallurgical compatibility of Ferro boron alloy which contain about 15 wt.% boron and some impurity elements like C(0.3),Si (0.29), P(0.006) etc, with 304 L SS have been evaluated using calorimetry and metallography. The X-ray diffraction of ferroboron revealed the presence of major FeB and minor Fe2B constituents, besides a small amount of Fe3(B, C). The thermal stability of this ferroboron alloy has been characterised up to melting by high resolution thermal analysis. In addition, the enthalpy increment measurements and hence specific heat estimates have been also made in the temperature range 400- 1200oC, using drop calorimetry. The high temperature metallurgical interaction between ferroboron and 304L SS clad has been simulated at temperatures 823 – 1073 K (550-800 oC) for reaction times up to 5000 h, using diffusion couples.