Effect of carbon on structural changes in Ni3Al phase

The paper presents diffraction and microscopic researches of a carbon influence on structural changes in Ni3Al phase. Ni3Al phase was acquired thanks to vacuum casting technology with a use of Exo-Melt process. A casting process was conducted in the atmosphere of argon. Two basic alloys were made with maintaining the nominal nuclear share equivalent to stoichiometry of Ni3Al phase. Next, carbon was instilled into the liquid alloy in the rate of 0,2% and 1,25% respectively for the first and for the second alloy. Final casts were cut into pieces and the samples were prepared in order to undertake and microscopic researches. Their phase composition was analyzed as well as their structural changes occurring within Ni3Al phase. Some changes along the lattice constants of Ni3Al phase were noticed, and they were 0,3580 nm and 0,3589 nm respectively for 0,2% C and 1,25% C. In the alloy consisting of 2,25% C a graphite (001) atomic plane was noticed. Its existence is connected with transgression in solubility limit of carbon in Ni3Al phase. This result was also confirmed by researches with SEM imaging, in which we observed numerous of separation of graphite of lamellar and nodular shape.