^aLaboratory of physical chemical study of materials (LEPCM), Department of

physics, Faculty of matter sciences, University of Batna 1, Algeria

^bDepartment of physics, Faculty of matter sciences, University of Batna 1, Algeria

The present paper reports the studies on Aluminum-based crystalline compounds AlTM (TM =Ru, Ir, Os and Rh).The random pseudobinary (A1-xBxC) compounds with compositions x = 0.25 and 0.5 have been investigated using Special Quasirandom Structures (SQS) approach. First principle calculations have been performed to investigate types of defect present in non-stoichiometric B2 AlTMphase. The results indicate that the Al-antisite defect and TM-antisite defect are the main defects present along Al-rich side and TM-rich side respectively. Additionally, at finite temperature along the Al-rich region, Al vacancies and along TM-rich side, TM vacancies which are the constituents of Schottky defect are the main thermal defects in B2 AlTM respectively.