microstrain

From micro- + strain.

microstrain (countable and uncountable, plural microstrains)

1. (physics) A strain expressed in terms of parts per million.
   • 2025 September 26, Grant Maloy Smith, “What Is a Strain Gauge Sensor and How Does It Work?”, in DEWESoft‎^[1], archived from the original on 14 November 2025:

     A strain is a dimensionless quantity and is usually expressed in percentages. Typical measures for strain are less than 2 mm/m for steel and are often expressed in micro-strain units. One microstrain is the strain producing deformation of one part per million.

2. (materials science) The root mean square of the variations in the lattice parameters across the individual crystallites, usually across microscopic distances, <ϵ²>^1/2. By definition, it cannot be negative. In contrast, macrostrain refers to the overall change in the lattice parameters caused by a composition change or temperature change or pressure change.
   • 2005, D. Scott MacKenzie, George E. Totten, Analytical Characterization of Aluminum, Steel, and Superalloys, →ISBN:

     The analysis of diffraction-line broadening is one of the most powerful methods to quantitatively analyze defects in crystalline materials. Values for crystallite-size and microstrain parameters can be obtained according to a variety of methods.

   • 2011, W Sha, Xiaomin Wu, K G Keong, Electroless Copper and Nickel-Phosphorus Plating, →ISBN, page 153:

     It should be noted that microstrain, which is larger at lower temperatures, is ignored in the calculation. The omission of microstrain causes the grain size to be underestimated which can be understood through Eq. 10.5.

   • 2013, E. J. Mittemeijer, U. Welzel, Modern Diffraction Methods, →ISBN:

     Thus, a Gaussian shape for the microstrain-broadened diffraction-line profile occurs for a Gaussian microstrain distribution.

• macrostrain