ChemInform Abstract: Contribution to the Ternary System Al‐Nb‐Ti.

Abstract

To clear up the phase relations in the title ternary system 22 binary and 35 ternary alloys are melted in an arc‐beam furnace with non‐consumable W electrode in a high‐purity Ar atmosphere.

A Study of the Kinetics of Phase Transformations in Nb-Ti-Al Alloys

“…While the results of the 40 at.% Al alloys that were investigated contradict all previous liquidus projections [15,20,22,52], they were supported by the experimental results of other investigators [17][18][19] which had been briefly described elsewhere [23]. Those experimental results, like the conclusions of this study, differed from past investigations of the liquidus projections by the most basic evidence, namely, that of confirming the high temperature ß phase field through quenching treatments.…”

“…The most recent liquidus projection by Zdziobeck et al [22] is presented in Figure 8.1, with the proposed changes to the primary solidification zones represented with dashed lines. The directions of the liquidus troughs within the range of the alloys that were examined were not found to differ from all of the previous liquidus projections [15,20,22,52]. From the appearance of the diagram, it is obvious that a further review of alloys closer to the Ti-Al binary is required, in particular, the refinement of the ß and y phase field boundaries in the area where they meet with the o solidification field.…”

Examination of solidification pathways and the liquidus surface in the Nb-Ti-Al system

“…[5] While a significant solubility of Ti within the ordered phases agreement with all previous reports of the liquidus surface of this alloy system. [3][4][5][6] While (100) peaks were not was observed at temperatures between 900 ЊC and 1400 ЊC, [13] the high-temperature ␤ phase field nonetheless observed in XRD patterns of all but one (5) of the as-cast ␤-solidified alloys, superlattice spots indicating B2 order extended further into the system than previously indicated. [4] The solidification path of alloy 12 (Nb-25Ti-25Al) helps were observed in the SAD patterns of all of these alloys.…”

“…Metallographic and BSEI examination (Figures 11 and 12) revealed large equiaxed grains containing an internal lamellar colony structure in multiple orientations. The lamellae were identified as ␥ (dark) and (light) phases C. Alloys Expected to be Solidified (6, 10, and 13) through BSEI (Figures 11(b) and 12(a) and (b)), XRD (Figure 12(e)), and TEM analysis (Figures 11(c) and (d), 12(c) In accordance with the accepted liquidus surfaces, [3,4,6] and (d)), with covering the grain boundaries. The microalloys 6 (Nb-30Ti-40Al), 10 (Nb-24Ti-40Al), and 13 (Nb20Ti-40Al) should have had as the primary solidification structure of all three ingots was found to share the same characteristics, with the only difference being an increase These results were interpreted in alloy 6 as the transition from a single-phase ␤ field into a ␤ ϩ two-phase field, in the volume fraction of the phase with an increase in the Nb:Ti ratio (compare Figure 11(b) with 12(a) and (b)).…”

“…extension of the primary ␤ solidification field beyond that The first complete investigation of the solidification phase proposed in References 4, 5 and 6. The high-temperature ␤ fields of the Nb-Ti-Al system was conducted by Kaltenbach phase field was reported by Hoelzer and Ebrahimi [7] in a et al [3] The liquidus projection was later refined through Nb-28Ti-30Al alloy and by Ebrahimi and De Aragao [8] in work by Perepezko et al, [4] following the establishment of a Nb-33Ti-40Al alloy, though previous liquidus projections the binary Ti-Al diagram to include the high-temperature would have placed these alloys in the primary phase field. ␣ phase field.…”