Intermetallic phase formation during combustion synthesis of mechanically activated Ni-Ti alloy
الموضوعات :
Seyed Khatiboleslam Sadrnezhaad
1
(
Sharif University of Technology
)
Shahin Katiraei
2
(
)
Abbas Ghasemi
3
(
)
الکلمات المفتاحية:
ملخص المقالة :
Intermetallic phase formation and oxidation reaction during combustion synthesis (CS) of Ni-Ti equiatomic mixture are affected by mechanical activation (MA) and pre-heating conditions. Important parameters are ignition time, reaction duration, temperature rise, microstructural change, titanium oxidation and intermetallic phase formation. Superelasticity and shape memory effects are influenced by two-stage austenite-rhombohedral and rhombohedral-martensite transformations detected by differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) of the combusted samples. Tension tests indicated superelastic behavior after 1 h, production of Ni3Ti after ½ h and delayed superelastic/thermoelastic behavior after 2 h MA. Results indicate that pre-combustion heating fosters mono-phase formation and titanium oxidation; while mechanical activation lowers ignition-start-time, synthesis-duration and Ni3Ti formation.