Influence of Mechanical Activation of Titanium-Containing Powders on Physical and Mechanical Properties of Sintered Products

Abstract

VT-22 alloy (Ti–6Al–4V), which belongs to the class of so-called transition (α + β)-titanium alloys, has a structure represented by α- and β-phases. Although it possesses high strength characteristics, making products from the powder of this alloy presents substantial challenges due to difficulties involved in pressing workpieces. To make high-quality products, binding components comprising plastic powder materials having a developed surface can be added. Computer modelling used to pre-evaluate the optimal percentage of VT-22 in a composite prior to pressing showed that this content was between 50 and 70%. Based on the modelling results, charges having six varying compositions were then selected. The first series of specimens was made using a charge subjected to normal mechanical mixing for one hour. The physical and mechanical properties of the resultant sintered specimens were studied. To study the effects of mechanical activation, an additional series of specimens was prepared from a charge mixed in a vibrating grinding mill for one hour. Comparative data of mechanical testing of the two series of sintered specimens of titanium-containing powders show that the mechanical activation of charges based on VT-22 powder improved the compatibility of specimens as well as greatly increasing resistance to mechanical abrasion. Testing for diametral compression of sintered specimens revealed two main failure types—brittle failure, when the specimen is fully destroyed, and plastic failure when the pellet edge is sheared. Mechanical activation was observed to increase the strength of almost all sintered specimens.