The influence of Zr alloying on the structure and properties of Al3Ti

• Published in: Intermetallics Vol. 11; no. 3; pp. 241 - 249
• Main Authors: Karpets, M V, Milman, Y V, Barabash, O M, Korzhova, N P, Senkov, O N, Miracle, D B, Legkaya, T N, Voskoboynik, I V
• Format: Journal Article
• Language: English
• Published: 01.03.2003
• ISSN: 0966-9795
• DOI: 10.1016/S0966-9795(02)00234-0

The phase stability and transformations in Al3(Ti1-xZrx) intermetallic alloys (x = 0-1) produced by arc melting were studied in the temperature range of 20 to 1100DGC by using an in situ X-ray diffraction (XRD) method. Two phases, D022 and D023, both having ordered tetragonal structures, were present at room temperature at zirconium concentrations from 1 to 10 at.% (x =0.04-0.4). At higher concentrations of Zr (0.4 < x < 1), only the D023 phase was detected. For the alloy with x = 0.32, the D023 transformed to D022 on heating at temperatures 1100DGC and above. On cooling, the D022 phase was stable to #~650DGC, and the D023 phase was formed again in the temperature range of 600-650DGC. The positional parameters of the D023 atomic structure in the alloy Al3(Ti0.68Zr0.32) were determined using a full-profile XRD analysis. It was shown that zirconium atoms substitute titanium atoms and increase the lattice parameters of the D023 structure. Zr fractions as small as x = 0.1 are required to stabilize the DO23 structure. A low temperature phase modification, Al24Ti8, was also detected in the surface layer in the temperature range below 650DGC and it was found to be a result of surface grinding. Mechanical properties of the alloys studied are also discussed.