Well the PhD interview dates have not been declared yet but you can follow the below process to check the dates when available

Visit the official site of the Indian Institute of Technology Madras IITM

A page like below image will open



There is a link of the notices option at the top

Hit on that link

You will find the link for the PhD interview dates at here only

At present these notifications are available


Physical Test events for the post of Security Guard
List of candidates called for re-examination for the post of Junior Technician (Mechanical Engineering Stream)
List of candidates called for re-examination for the post of Junior Superintendent
Announcement for the post of "Junior Research Fellow" in the Department of Biotechnology
List of candidates called for re-examination for the post of Security Guard
NATIONAL CANCER TISSUE BIO BANK, DEPARTMENT OF BIOTECHNOLOGY, IITM CHENNAI .
List of candidates selected for the post of Junior Technician - Advt. No. IITM/R/1/2016 dated 22.01.2016
Announcement for the post of "Project Associate in the Department of Engineering Design
List of candidates selected for the post of Junior Technical Superintendent - Advt. No. IITM/R/1/2016 dated 22.01.2016
International Conference on ADVANCES IN SCIENTIFIC COMPUTING 2016
Announcement for the post of "Junior Executive" in the Centre for IC&SR
Announcement for the post of "Project Technician" in the Department of Bio Technology
Announcement for the post of "Junior Research Fellow" in the Department of Bio Technology
Announcement for the post of "Research Associate" in the Department of Applied Mechanics
Announcement for the post of "Research Associate III (RA-III)" in the Department of Physics.
Alumnite 2016 Prize Winners.