Carl J. McHargue

Structure of Ceramic Surfaces Modified by Ion Beam Techniques

Modification of the near-surface region of materials by use of energetic ion beams has been investigated extensively in recent years. The nature of the process allows one to introduce any element into the near-surface region of solids in a controlled and reproducible manner that is independent of most equilibrium constraints. Since the process is nonequilibrium in nature, compositions and structures unattainable by conventional methods may be produced.

Structure Property Relationships in Ion Implanted Ceramics

Ion implantation is used to alter the near-surface properties of materials in a manner which is independent of many of the constraints associated with normal processing methods. Since virtually any element can be injected into a solid in a controlled and reproducible fashion, this doping process (nonequilibrium in nature) often leads to compositions and structures unobtainable by conventional means. Although ion implantation doping has had its greatest success in semiconductor technology, it has been utilized in recent years to alter the physical and chemical properties of metals, and the optical and electrical properties of insulators. Relatively little work has been reported on changes in the mechanical properties of insulators (ceramics) as a result of ion implantation.

Microstructural Development of TiB2 Ion Implanted with 1 Mev Nickel

An Analytical Electron Microscopy (AEM) investigation of polycrystalline TiB 2 implanted with 1 MeV Ni+ to 1 × 10 21 ions/m 2 has shown that the implanted region remained crystalline and showed no evidence of precipitation. A region containing tangled dislocations extended from the implanted surface to ∼500 nm. Between ∼500 and 750 nm, the microstructure was more complicated and could be indicative of a high density of 5 to 10 nm diam defects. The maximum nickel concentration determined by energy dispersive spectroscopy (EDS) occurred at ∼450 nm, slightly deeper than the calculated depth of 390 nm. Observations after in situ annealing revealed cavities and nickel-rich precipitates. Radiation damage models are invoked to explain the microstructures observed.

Structure-Mechanical Property Relationships in Ion Implanted Ceramics

Although the majority of research and development involving ion implantation has been devoted to the doping of semiconductors, there has also been much activity toward altering the chemical, physical, and mechanical properties of metals and alloys. In recent years, there has been a resurgence of interest in the use of ion beams to alter the properties of insulating materials. As a class of materials, insulators exhibit a range of properties, structures, phases, chemical bonding types, etc. This paper will consider the portion of that class called ceramics, primarily the crystalline oxides and carbides that find technological applications today. 30 refs., 10 figs., 1 tab.