Metallurgical and Materials Transactions A

, Volume 31, Issue 7, pp 1857–1865

Processing and characterization of Ti2AlC, Ti2AlN, and Ti2AlC0.5N0.5

  • M. W. Barsoum
  • T. El-Raghy
  • M. Ali
Article

DOI: 10.1007/s11661-006-0243-3

Cite this article as:
Barsoum, M.W., El-Raghy, T. & Ali, M. Metall and Mat Trans A (2000) 31: 1857. doi:10.1007/s11661-006-0243-3

Abstract

In this article, we report on the fabrication and characterization of Ti2AlC, Ti2AlN, and Ti2AlC0.5N0.5. Reactive hot isostatic pressing (hipping) at ≈40 MPa of the appropriate mixtures of Ti, Al4C3 graphite, and/or AlN powders for 15 hours at 1300 °C yields predominantly single-phase samples of Ti2AlC0.5N0.5, 30 hours at 1300 °C yields predominantly single-phase samples of Ti2AlC. Despite our best efforts, samples of Ti2AlN (hot isostatic pressed (hipped) at 1400 °C for 48 hours) contain anywhere between 10 and 15 vol pct of ancillary phases. At ≈25 µM, the average grain sizes of Ti2AlC0.5N0.5 and Ti2AlC are comparable and are significantly smaller than those of Ti2AlN, at ≈100 µm. All samples are fully dense and readily machinable. The room-temperature deformation under compression of the end-members is noncatastrophic or graceful. At room temperature, solid-solution strengthening is observed; Ti2AlC0.5N0.5 is stronger in compression, harder, and more brittle than the end-members. Conversely, at temperatures greater than 1200 °C, a solid-solution softening effect is occurring. The thermal-expansion coefficients (CTEs) of Ti2AlC, Ti2AlN, and Ti2AlC0.5N0.5 are, respectively, 8.2 × 10−6, 8.8 × 10−6, and 10.5 × 10−6 °C−1, in the temperature range from 25 °C to 1300 °C. The former two values are in good agreement with the CTEs determined from high-temperature X-ray diffraction (XRD). The electrical conductivity of the solid solution (3.1 × 106 (Θ m)−1) is in between those of Ti2AlC and Ti2AlN, which are 2.7 × 106 and 4.0 × 106Θ−1 m−1, respectively.

Copyright information

© ASM International & TMS-The Minerals, Metals and Materials Society 2000

Authors and Affiliations

  • M. W. Barsoum
    • 1
  • T. El-Raghy
    • 1
  • M. Ali
    • 2
  1. 1.the Department of Materials EngineeringDrexel UniversityPhiladelphia
  2. 2.Temple UniversityPhiladelphia