Microstructural development in the near-surface region during thermal annealing of Al 2 O 3 implanted with cationic impu
- PDF / 2,185,583 Bytes
- 18 Pages / 593.28 x 841.68 pts Page_size
- 87 Downloads / 156 Views
P. S. Sklad Metals and Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831
C.W. White Solid State Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831
C. J. McHargue Metals and Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (Received 20 September 1989; accepted 20 March 1990)
Single-crystal A12O3 was implanted with cationic impurities in the dose range 1-4 x 1016/cm2 and subsequently annealed in either an oxidizing or reducing environment. Following annealing at 1200 °C or higher, crystalline precipitates or solid solutions are observed, which are consistent with what is expected from the equilibrium phase diagram.
I. INTRODUCTION
This paper describes the results of implantation and thermal annealing on the near-surface region of A12O3. Ion irradiation of metal surfaces to modify the microstructural and metallurgical properties of metals has become almost a routine procedure.1'2 Ion implantation of Si has also become essential in the fabrication of silicon based electronics.3 Application of ion beam techniques to structural ceramics and insulators is a more recent effort.4'5 Many of these materials, and in particular A12O3, are sensitive to the condition of the surface. Tensile surface stress can give rise to crack propagation and low fracture toughness. Surface hardness will affect the wear properties of ceramic or ceramic coated tools. This very practical interest has motivated an increasing number of groups to investigate the effects of irradiation on the hardness and fracture toughness of ion-implanted A12O3 and the modified microstructure which gives rise to these properties.6"9 In addition, the solubility of most impurities in AI2O3 is vanishingly small.10 The properties of supersaturated solutions of AI2O3, which might result from ion implantation with almost any impurity, are therefore unknown and would be of general interest. In this paper we will concentrate on the microstructures which arise from ion implantation and post-implantation thermal annealing with a particular interest in the formation of equilibrium versus nonequilibrium compositions. Many investigations have concerned themselves with the gross structural effects of implantation into A12O3611 or lattice location studies of the implanted ions.12"14 Annealing studies of A12O3 implanted with 1502
http://journals.cambridge.org
ions of gases15 19 or cationic impurities6 818 22 have also been made. These results are reviewed by McHargue4 and by White et al.5 The results of Naramoto et al.1 and preliminary results of our own21 indicate that the chemistry of the implanted ion largely determines the microstructure. In this paper we report the results of a systematic examination of the relationship of ion chemistry to the development of surface microstructure which results from room temperature implantation and subsequent thermal annealing of A12O3. Three sets of implant species are considered. The group III-B elements Al, Ga, and In were implanted as candidates for direct repl
Data Loading...
