کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
702348 1460810 2011 7 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Effects of grain size and temperature on mechanical and failure properties of ultrananocrystalline diamond
موضوعات مرتبط
مهندسی و علوم پایه سایر رشته های مهندسی مهندسی برق و الکترونیک
پیش نمایش صفحه اول مقاله
Effects of grain size and temperature on mechanical and failure properties of ultrananocrystalline diamond
چکیده انگلیسی

Molecular dynamics simulations of ultrananocrystalline diamond (UNCD), with random distribution of grain sizes and grain boundaries (GBs), are performed to investigate the effect of grain size and temperature on the mechanical properties and failure mechanisms under tensile loading. Results show that when the grain size of UNCDs decreases from 4.1 nm to 2.26 nm, the Young's modulus decreases from 891 GPa to 840 GPa, while the obtained intrinsic fracture strength, 113 GPa, is insensitive to the grain size. Elastic softening is attributed to the increased volume fraction of amorphous-like atoms. Our analysis reveals that at room temperature, UNCD fails via sliding along a grain boundary with a large shear stress. Such sliding triggers crack initiation at an adjacent triple junction and subsequent propagation along an adjacent grain boundary with a large normal stress. With increasing temperature, a crossover from grain sliding to a direct intergranular fracture is observed. The crossover is caused by a different dependence of GB shear and tensile strength on temperature. The present work provides information that may be useful to the design and optimization of the mechanical properties and failure behavior of UNCDs.


► We simulate Ultrananocrystalline Diamond (UNCD) models by molecular dynamics.
► UNCD fracture strength is grain size insensitive in contrast with Young’s modulus.
► UNCD fails by grain slide followed by intergranular fracture at low temperature.
► High temperature induces direct intergranular fracture.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Diamond and Related Materials - Volume 20, Issue 10, November 2011, Pages 1303–1309
نویسندگان
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