Abstract
BackgroundFor a full understanding of the mechanical properties of a material, it is essential to understand the defect structures and associated properties and microhardness indentation is a technique that can aid this understanding.ResultsThe Vickers hardness on (010), {011} and {110} faces lay in the range of 304–363 MPa. The Knoop Hardnesses on the same faces lay in the range 314–482 MPa. From etching of three indented surfaces, the preferred slip planes have been identified as (001) and (101). For a dislocation glide, the most likely configuration for dislocation movement on the (001) planes is (001) [100] (|b| = 0.65 nm) and for the (101) plane as (101) left[10overline{1}right] (|b| = 1.084 nm) although (101) [010] (|b| = 1.105 nm) is possible. Tensile testing showed that at a stress value of 2.3 MPa primary twinning occurred and grew with increasing stress. When the stress was relaxed, the twins decreased in size, but did not disappear. The twinning shear strain was calculated to be 0.353 for the (101) twin plane.ConclusionsHMX is considered to be brittle, compared to other secondary explosives. Comparing HMX with a range of organic solids, the values for hardness numbers are similar to those of other brittle systems. Under the conditions developed beneath a pyramidal indenter, dislocation slip plays a major part in accommodating the local deformation stresses.Graphical abstractHMX undergoing tensile testing.Electronic supplementary materialThe online version of this article (doi:10.1186/s13065-015-0091-6) contains supplementary material, which is available to authorized users.
Highlights
ResultsThe Vickers hardness on (010), {011} and {110} faces lay in the range of 304–363 MPa. The Knoop Hardnesses on the same faces lay in the range 314–482 MPa. From etching of three indented surfaces, the preferred slip planes have been identified as (001) and (101)
To develop a firm understanding of the mechanical properties of any given material, it has been established that in addition to understanding the crystal structure, a knowledge of the defect structures and their properties is essential [1,2]
Microhardness indentation is a useful technique for such an investigation, as it can yield a great deal of information from a careful study
Summary
The Vickers hardness on (010), {011} and {110} faces lay in the range of 304–363 MPa. The Knoop Hardnesses on the same faces lay in the range 314–482 MPa. From etching of three indented surfaces, the preferred slip planes have been identified as (001) and (101). The most likely configuration for dislocation movement on the (001) planes is (001) [100] (|b| = 0.65 nm) and for the (101) plane as (101) ⎡⎣101⎤⎦ (|b| = 1.084 nm) (101) [010] (|b| = 1.105 nm) is possible. Tensile testing showed that at a stress value of 2.3 MPa primary twinning occurred and grew with increasing stress. When the stress was relaxed, the twins decreased in size, but did not disappear. The twinning shear strain was calculated to be 0.353 for the (101) twin plane
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