Nature and Growth of Interaction Layers Formed during the Reaction between Solid Ni and Liquid Al

The nature and growth of the interaction layers between solid Nb and liquid Al has been studied by carrying out the tests on Nb(s)-Al(l) and Nb(s)-Al(l)-Ni(s) reaction couples isothermally reacted between 700℃ and 900℃ for different time intervals.It has been found that the interaction layer between Nb and Al contains two parts: a thin continuous layer of NbAl3 adjacent to the Nb surface and a two-phase zone constituted of NbAl3 particles dispersed in an Al matrix. Although the nature and growth of interaction layers follows the four-stage mechanism, a typical cruciform pattern does not occur in Nb(s)-Al(l) reaction couples. However, a cruciform pattern was observed in Nb(s)-Al(l)-Ni(s) reaction couples. The movement of NbAl3 particles is important to the production of cruciform pattern in the reaction couples.