Available online at www.sciencedirect.com ScienceDirect Materials Today: Proceedings 5 (2018) 16904–16911 www.materialstoday.com/proceedings 2214-7853 © 2018 Elsevier Ltd. All rights reserved. Selection and/or Peer-review under responsibility of Advances in Materials & Processing: Challenges & Opportunities (AMPCO-2017). AMPCO-2017 Crystallite size and microstrain in mechanically alloyed and heat treated Fe-25 wt.% Y 2 O 3 Sunil Kumar Rajulapati a , Avinash Deepak Saggurthi a , Akeshwar Singh Yadav a , Sai Ramudu Meka a, * a Metallurgical and Materials Engineering Department, IIT, Roorkee 247667, India Abstract The main problem in characterizing the commercial ODS steel to understand fundamentally the underlying microstructural changes is associated with the very small volume fraction of Y 2 O 3 which obstructs the application of, statistically reliable, bulk material characterization techniques like X-ray diffraction. Furthermore, the commercial ODS steels have other precipitation reactions which also complicates the understanding of the sole influence of Y 2 O 3 on the microstructure evolution. In order to overcome these difficulties, in this study the high Y 2 O 3 containing Fe-25 wt.% Y 2 O 3 model alloy was chosen which allows the application of X-ray diffraction line profile analysis to trace the evolution of both ferrite and Y 2 O 3 crystallite sizes and microstrains as a function of different processing steps like ball milling and the following heat treatments. No significant change in the lattice parameter of ferrite matrix has been observed after ball milling suggesting the negligible solubility of Y 2 O 3 in ferrite matrix even after ball milling. During heat treatment at 1200 o C the micro strain of the ferrite matrix has decreased with simultaneous increase in crystallite size and the same phenomena was also observed for Y 2 O 3 as well. During the following second heat treatment at 1060 o C (i.e., the powder heat treated at 1200 o C was further heat treated at 1060 o C) no significant change in crystallite size of Y 2 O 3 occurred whereas the ferrite crystallite size has significantly decreased. This decrease in crystallite size of ferrite during second heat treatment has been attributed to the smaller austenite grain size after second heat treatment at 1060 o C than the first heat treatment at 1200 o C. © 2018 Elsevier Ltd. All rights reserved. Selection and/or Peer-review under responsibility of Advances in Materials & Processing: Challenges & Opportunities (AMPCO-2017). Keywords: ODS Steels; Mechanical Alloying; X-Ray Diffraction; Heat Treatment * Corresponding author. Tel.: +91-1332-284860; fax: +91-1332-285243. E-mail address: sairamudu@gmail.com