Crack-arresting compression layers produced by ion implantation

doi:10.1016/j.nimb.2005.08.064

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms

Volume 242, Issues 1–2, January 2006, Pages 421-423

https://doi.org/10.1016/j.nimb.2005.08.064 Get rights and content

Abstract

Compression layers were produced in aluminium oxide and magnesium oxide samples using high energy ion implantation. In the experiments, the samples were implanted with 3.0 MeV H⁺ ions to a fluence of 3.3 × 10¹⁷ cm⁻² over the area of ∼3.0 cm². The lattice expansion and compressive stress distribution with depth was measured using high resolution Raman microscopy. The implantation-induced compression layers were demonstrated to represent effective barriers for arresting the propagating cracks. Major factors that govern the crack closure, in particular the effect of ion energy and state of stress on the localization and efficiency of the implantation-induced compression layers, are discussed.

Introduction

Ion implantation is known to produce lattice expansion in a number of ceramic materials which is attributed to injection of ions, production of point defects, structural change, charge accumulation and other factors [1], [2]. Such expansion is constrained by the bulk of a sample, thus resulting in compressive stresses in the implanted layer. The compressive stress is beneficial for suppressing crack propagation in particular in brittle ceramic materials easily fractured under dynamic loading. The efficiency of crack arrest depends on the distribution and magnitude of the implantation-induced compressive stress as well as the tensile stress that causes the crack propagation. The high-energy low-mass ions have a long ion range and thus produce the compressive stress layer relatively deep below the surface. It is expected to be particularly efficient in crack arresting in cases where the applied tensile stress reduces from the surface to the sample interior.

This work aims at investigating the distribution of the implantation-induced compressive stress within the implanted layer using a high resolution Raman probe and analysing its interaction with cracks propagating under thermal shock.The efficiency of the compressive stress barrier in arresting propagating cracks is explored.

Section snippets

Experiment

The ( $11 \bar{2} 0$ ) and (0 0 1) faces of sapphire and magnesium oxide single crystals, respectively, are uniformly implanted with 3.0 MeV H⁺ ions to a fluence of 3.3 × 10¹⁷ cm⁻² at room temperature. The samples used are ∼10 mm thick with the implanted surface area of ∼15 × 30 mm². The ion range under these conditions is 50 μm for sapphire and 60 μm for magnesium oxide crystals as determined by SRIM calculations and verified by optical microscopy. Following implantation, the cross sectional planes of sapphire are

Results and discussion

Direct evidence of crack arrest is demonstrated in the optical photographs presented in Fig. 1(a) for MgO and in (b) for sapphire. The photographs are taken from cross sections made perpendicular to the ion implanted faces of the crystals. Both photographs show that the thermal shock-initiated cracks are effectively stopped within the implanted layer. Fig. 1(a) indicates that in the unimplanted region of the MgO crystal, cracks propagate to the depth of ∼360 μm and deeper, while in the adjacent

Conclusion

Compressive stress layers are produced in sapphire and magnesium oxide crystals using 3.0 MeV H⁺ ion implantation. The layers are observed to represent effective crack-arresting barriers. The implantation-induced compressive stress distribution and its effect on crack closure are considered. The analysis is used to evaluate the range of crack propagation and the efficiency with which cracks are arrested in the implanted magnesium oxide and sapphire crystals subjected thermal shock loading.

References (7)

V.N. Gurarie et al.
Nucl. Instr. and Meth. B
(1999)
V.N. Gurarie
Mater. Sci. Eng.
(2000)
C.W. White et al.
Ion Implantation and Annealing of Crystalline Solids
(1989)

There are more references available in the full text version of this article.

Cited by (0)

View full text