1. Material Characterisation Division, Materials and Metallurgy Group, Vikram Sarabhai Space Center, Trivandrum-695 022, IN (Corresponding author), e-mail: narayanamurty_susarla@vssc.gov.in
2. Material Characterisation Division, Materials and Metallurgy Group, Vikram Sarabhai Space Center, Trivandrum-695 022, IN
3. Liquid Propulsion Systems Center, Valiamala P.O., Trivandrum-695 547, IN