Solid-particle erosion data have been reported for many materials. The mechanics of the impact process has also been examined. However, relatively little effort has been expended in studying the microstructural aspects of material response to erosion. Effects such as deformation hardening, plastic flow, and particle embedding are recognized as being important but have not been subjected to careful study. Understanding the erosion mechanism at large attack angles and accounting for differences in erosion behavior of different metals and alloys are areas where knowledge of materials response factors will be most important. In the present work surface and subsurface erosion damage in copper is investigated by transmission and scanning electron microscopy techniques.

in 1988 by Congress to "assist industry in the development of technology. .. needed to improve product quality, to modernize manufacturing processes, to ensure product reliability. .. and to facilitate rapid commercialization ... of products based on new scientific discoveries." NIST, originally founded as the National Bureau of Standards in 1901, works to strengthen U.S. industry's competitiveness; advance science and engineering; and improve public health, safety, and the environment. One of the agency's basic functions is to develop, maintain, and retain custody of the national standards of measurement, and provide the means and methods for comparing standards used in science, engineering, manufacturing, commerce, industry, and education with the standards adopted or recognized by the Federal Government. 'At Boulder, CO 80303. 2 Some elements at Boulder, CO 80303.

Laboratory studies have been conducted of wear processes occurring in BEP currency and stamp printing operations. Conclusions were drawn on the principal modes of wear involved. Laboratory work was carried out to develop new wear test methods that could be used to evaluate materials such as improved chromium plating, and to determine the abrasiveness of printing ink constituents.