Peculiarities of Mechanical Activation and Subsequent Thermal Explosion in the Powder System Nickel – Titanium

Abstract

There was undertaken experimental studies of mechanical activation (MA) of stoichiometric mixture of titanium and nickel powders (Ti–55,06 wt.%Ni) and subsequent SHS combustion (self-propagation high-temperature synthesis) in the mode of thermal explosion. Process MA carried out in high- energy planetary ball mill (60 g) in air during from 30 s to 10 min. Thereafter received mixture was placed in specially designed unit of constant vo- lume where was carrying out heating up to thermal explosion occurrence. There was determined temperature of the heat evolution’s beginning, critical and maximum temperature by using pattern of temperatures. Structure and composition of studied mechano-activated powders and com- bustion products were investigated by means of scanning electron microscopy, optical metallography, and X-ray phase analysis. It has been found that nonmonotonic time dependences of thermal explosion’s temperature characteristics were connected with self-lining processes that lead to de- viation of activated mixture’s composition from original composition.