Effects of Ti and High Cooling Rate on the Phase Equilibria and Properties of Ni 3 (Al,V) Alloys

Investigations of the Ni 3 (Al,V,Ti) alloys with 5 at.% Ti addition show that high quenching rates from the liquid state allow for the preservation of the metastable Ni(Al,V,Ti) solid solution at low temperatures as well as for the limitation of the eutectoid decomposition range. Annealing at the temperatures close to the eutectoid decomposition causes an increase in the amount of the Ni 3 Al and Ni 3 V equilibrium phases, as well as the precipitation of the Ni 3 Ti phase. The V addition reveals the ability to stabilize Ni solid solution, while Ti retards Ni 3 V phase precipitation but also supports the precipitation of the Ni 3 Ti phase, in spite of the higher than 5 at.% range of Ti solubility in the Ni 3 V phase. The increase in V and Ti content at the cost of a decrease in Al content strongly increases micro-hardness of the alloys crystallized at high rates. For the alloys containing predominantly V, increased ductility was noticed in the temperature range of the dissolution of Ni 3 V precipitates.