Abstract
Recent high resolution transmission electron microscopy and electron probe X-ray microanalysis show that the compound originally thought to be Ti3Al2N2 is Ti4AlN3. In this paper we report on the crystal structure determination by Rietveld refinement on neutron and X-ray powder diffraction data. Ti4AlN3 crystallizes with a hexagonal unit cell, space group P63/mmc, and with lattice parameters a = 2.9880(2) and c = 23.372(2) angstroms. The stacking sequence is such that every four layers of Ti atoms is separated by a layer of Al atoms. The N atoms occupy octahedral sites between the Ti atoms making up a network of corner shared octahedra. This compound is closely related to other layered, ternary, machinable, hexagonal nitrides and carbides, namely, M2AX and M3AX2, where M is an early transition metal, A is a A-group element and X is either C and/or N.
Original language | English |
---|---|
Pages (from-to) | 1785-1796 |
Number of pages | 12 |
Journal | Materials Research Bulletin |
Volume | 35 |
Issue number | 11 |
DOIs | |
State | Published - Aug 2000 |
Externally published | Yes |
Funding
This research was sponsored by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Transportation Technologies, as part of the High Temperature Materials Laboratory User Program, Oak Ridge National Laboratory. ORNL is managed by Lockheed Martin Energy Research Corp. for the U.S. Department of Energy under contract number DE-AC05-96OR22464. This work was also partially funded by the Division of Materials Research of the National Science Foundation (DMR 9705237). CMH was supported in part by an appointment to the ORNL Postdoctoral Research Associates program jointly administered by ORAU and ORISE. The authors also thank Dr. Bryan Chakoumakos, ORNL, for assistance with the neutron powder diffraction data collection and processing.