Reinvestigation of Ni-solid solution/liquid equilibria in Ni-Al binary and Ni-Al-Zr ternary systems

Abstract

The present work reports the results of a reinvestigation of the ␥ liquidus and solidus temperatures of the Ni-Al system and the ␥ /Ni 5 Zr eutectic reaction temperatures in the Ni-Al-Zr system. In the Ni-Al binary system, it is found that the stability of the Ni-rich ␥ solid solution phase is enhanced by small additions of Al with the melting temperature of the ␥ phase and that the melting temperature reaches a congruent maximum at a few at.% Al. The temperature of the eutectic reaction L → ␥ ؉ Ni 5 Zr in the Ni-Zr binary edge is confirmed to be 1196 ؇C by differential thermal analysis (DTA), rather higher than the value reported previously. The reaction temperature increases with Al addition to reach or exceed 1206 ؇C, forming a "saddle point," then decreasing to reach 1187 ؇C or below by flowing into a ternary invariant reaction. These findings can be explained by ␥ /liquid equilibrium in the Ni-Al binary system. addition on the temperature of the eutectic reaction L → ␥ ϩ Seiji Miura, Hiroto Unno, Tetsuro Yamazaki, Satoshi Takizawa, and between melting points can be measured directly.

Isothermal Sections of Al-Ni-Zr Ternary System at 850 and 1050 °C

“…7(a), a solidification path can be inferred, with large primary phase c¢ solidified from the liquid first, L fi c¢; after that the liquid composition reached the univariant line, L fi c¢ + Ni 5 Zr; finally, the liquid composition reached the eutectic invariant reaction, L fi c¢ + Ni 5 Zr + c. Composition of sample #3 (Al-77Ni-13Zr) is identical to that in Miu. [34] According to EPMA results, the white primary phase is Ni 7 Zr 2 , the eutectic microstructure is consistent of gray one (Ni 5 Zr) and black one (c¢), as shown in Fig. 7(d Fig.…”

“…8 The projections of Ni-rich region of Al-Ni-Zr system (a) proposed by Nash [32] (b) proposed by Ghosh [33] primary Ni 7 Zr 2 was formed, with microstructure consisting mainly of c¢ + Ni 5 Zr as those observed in Miu. [34] In brief, according to as-cast microstructure analysis of additional samples above, there may exist two invariant reactions, i.e. L + Ni 7 Zr 2 fi Ni 5 Zr + c¢ and L fi c¢ + Ni 5 Zr + c, in the projection of Ni-rich region of the Al-Ni-Zr system.…”

“…Ghosh [33] disagree with the liquidus projection proposed by Nash [32] based on the microstructure (c¢ + Ni 5 Zr) observed by Miu. [34] But this microstructure (c¢ + Ni 5 Zr) may not as a proof to oppose Nash [32] because the sample used by Miu [34] being annealed at 1000°C for 6 days. Later, Mot [36] proposed the similar liquidus projection as given by Nash [32] after analyzed the microstructure he observed and compared with the projection of Al-Ni-Hf system.…”

“…[5,6] In order to better understand alloy properties and develop new materials, knowledge concerning phase equilibria of AlNi-Zr alloy system is of fundamental importance. The constituent binary subsystems Al-Ni, Al-Zr and Ni-Zr have been extensively investigated both experimentally and ther- However, Ghosh [33] pointed out that such a reaction is conflicting with the coexistence of c¢ and Ni 5 Zr observed by Miu [34] and proposed partial liquidus projection base on the result of Miu [34] in 2005. Later, Rag [35] reviewed briefly the liquidus projection at Ni-rich corner and also agreed with the result of Miu [34] in 2006.…”

“…The constituent binary subsystems Al-Ni, Al-Zr and Ni-Zr have been extensively investigated both experimentally and ther- However, Ghosh [33] pointed out that such a reaction is conflicting with the coexistence of c¢ and Ni 5 Zr observed by Miu [34] and proposed partial liquidus projection base on the result of Miu [34] in 2005. Later, Rag [35] reviewed briefly the liquidus projection at Ni-rich corner and also agreed with the result of Miu [34] in 2006. But, Mot [36] reported again a similar reaction (L M c + Ni 5 Zr + Ni 7 Zr 2 ) to Nash [32] in 2011.…”