Production of Ni3Ti-TiC x intermetallic-ceramic composites employing combustion synthesis reactions

Abstract

Combustion synthesis (CS) of nickel, titanium, and carbon (graphite) reactant particles can result in NiTi-TiC (stoichiometric) or Ni 3 Ti-TiC x (nonstoichiometric) composites. Since NiTi exhibits both superelasticity and shape memory properties while Ni 3 Ti does not, it is important to understand the SHS reaction conditions under which each of these composite systems may be synthesized. The stoichiometry of TiC x , for which 0.3 Յ x Յ 0.5, has an important controlling effect on the formation of either Ni 3 Ti or NiTi; i.e., formation of TiC 0.7 results in a depletion of titanium and formation of Ni 3 Ti. This deficiency should be considered when developing the SHS reaction. This article examines the SHS conditions under which Ni 3 Ti-TiC x composites are produced. Ignition, combustion, and microstructure characteristics of nickel, titanium, and carbon (graphite) particles were investigated as a function of initial relative density and thermophysical properties of the reactant mixture. Combination of the thermophysical properties and burning velocities controlled TiC x particle size, yielding a dependence of particle size on cooling rate. Theoretical calculations were performed and are in good agreement with the experimental data presented.

The effect of the heat treatment on the structure and properties of sintered TiC-Ti-Ni, TiC-Ni-Fe alloys

“…На оставшихся монолитных образцах были изго-товлены микрошлифы и проведено измерение твер-дости на приборе Виккерса, по результатам которого установлены значения критического коэффициента интенсивности напряжений К 1C по зависимости (1), [13,14] …”

“…где l -длина радиальной трещины, мкм; a -половина диагонали отпечатка, мкм; P -нагрузка при приборе Виккерcа, от 50 до 500 Н [13]. Параметр микрохрупкости γ был определен по за-висимости (2), а параметр Палмквиста для радиаль-ных трещин по зависимости (3) [15]:…”