Mechanical properties of β-HMX

Gallagher, H.G.; Miller, John C.; Sheen, D. B.; Sherwood, J. N.; Vrcelj, Ranko M.

doi:10.1186/s13065-015-0091-6

Cited by 52 publications

(55 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Table 1 shows several slip systems cited in the literature for monoclinic β-HMX, ranked in the order of a hkl /b mnp . We observe that the slip systems observed experimentally [17], Figure 1. Several low index planes in β-HMX, with potential of being slip planes: (a) (001), (b) (011), (c) (101) and (d) (021).…”

Section: Models and Proceduresmentioning

confidence: 53%

Peierls–Nabarro stresses of dislocations in monoclinic cyclotetramethylene tetranitramine (β-HMX)

Pal

Picu

2018

Modelling Simul. Mater. Sci. Eng.

View full text Add to dashboard Cite

HMX (cyclotetramethylene tetranitramine) is an energetic material which releases substantial amounts of energy upon decomposition. The role of defects and deformation in causing reaction initiation was discussed in the literature but remains insufficiently understood. In this work, we identify, using computational methods, the slip systems which are potentially active in β-HMX and rank them in terms of their propensity for slip. To this end, we develop first a tentative ranking based on the degree of steric hindrance associated with slip. This is quantified using a geometric analog of the γ-surface. Further, we use atomistic models to compute the Peierls-Nabarro (PN) stress for the motion of dislocations in the slip systems with smallest degree of steric hindrance. A complex mechanical behavior is observed, including strong slip asymmetry, twinning and cleavage. The five systems with the lowest PN stress are ()[ ] 011 011 , ()[ ] 011 100 , ()[ ] 101 010 , ()[ ] 101 101 and ()[ ] 021 100. We conclude that the material has enough slip systems available for supporting a generalized state of plastic strain provided the twinning system ()[ ] 101 101 is taken into consideration and that the resolved shear stress is at least 260 MPa.

show abstract

Section: Models and Proceduresmentioning

confidence: 53%

Peierls–Nabarro stresses of dislocations in monoclinic cyclotetramethylene tetranitramine (β-HMX)

Pal

Picu

2018

Modelling Simul. Mater. Sci. Eng.

View full text Add to dashboard Cite

show abstract

“…2 The importance on crystal shapes of β-HMX has been emphasized until today because the shock sensitivity is strongly influenced by the anisotropy of crystal faces. The multiscale modeling carried out by Zamiri and De indicates that the shock response differs with crystallographic directions.…”

Section: Introductionmentioning

confidence: 99%

Prediction of Growth Habit of β-Cyclotetramethylene-tetranitramine Crystals by the First-Principles Models

Shim

Koo

2015

Crystal Growth & Design

View full text Add to dashboard Cite

Experimentally, β-cyclotetramethylene-tetranitramine (β-HMX) crystals were found to dramatically elongate to the [100] direction when a relatively high supersaturation was imposed. A sudden growth of β-HMX to the [100] direction is closely associated with a mechanistic transition from spiral growth to two-dimensional (2D) nucleation for the (110) face. The onset supersaturation for the growth by 2D nucleation, σ 2D , was found to play a key role in the growth of β-HMX. The present simulation results based on first-principles models such as the spiral growth model and the 2D nucleation model show that the values of σ 2D on the (101) and (101̅ ) faces are smaller than those on the (020), (110), and (011) faces. This leads to the prediction of rapid growth rates for the (101) and (101̅ ) faces by 2D nucleation at low supersaturation and the appearance of a typical shape of β-HMX. On the other hand, the needle-like shape of β-HMX begins to prevail when the supersaturation exceeds the σ 2D for the (110) face because its growth mechanism is transformed from the spiral growth mechanism to the 2D nucleation mechanism which accompanies rapid growth of the (110) face. As a result, the present predictions are in remarkable agreement with the experiments. Furthermore, the kinetic Monte Carlo (KMC) simulation also shows that the σ 2D for the (110) face is lower than that for the (011) face because the (011) face provides the surface topology on which growth units are unfavorably incorporated into the lattice sites. It evidently shows that the relative positions of σ 2D bring on the advent of needle-like growth of β-HMX.

show abstract

“…However, pointed pits appear only at the surface intersection of dislocations. Later studies of localized plastic deformation [36] using a microhardness indenter resulted in an increase in etch pit density around the indentation, with rows of pits aligned along well-defined dislocation slip traces.…”

Section: Resultsmentioning

confidence: 99%

Growth and dislocation studies of β-HMX

Gallagher

Sherwood

Vrcelj

2014

Chemistry Central Journal

Self Cite

View full text Add to dashboard Cite

BackgroundThe defect structure of organic materials is important as it plays a major role in their crystal growth properties. It also can play a subcritical role in “hot-spot” detonation processes of energetics and one such energetic is cyclotetramethylene-tetranitramine, in the commonly used beta form (β-HMX).ResultsThe as-grown crystals grown by evaporation from acetone show prismatic, tabular and columnar habits, all with {011}, {110}, (010) and (101) faces. Etching on (010) surfaces revealed three different types of etch pits, two of which could be identified with either pure screw or pure edge dislocations, the third is shown to be an artifact of the twinning process that this material undergoes. Examination of the {011} and {110} surfaces show only one type of etch pit on each surface; however their natural asymmetry precludes the easy identification of their Burgers vector or dislocation type. Etching of cleaved {011} surfaces demonstrates that the etch pits can be associated with line dislocations. All dislocations appear randomly on the crystal surfaces and do not form alignments characteristic of mechanical deformation by dislocation slip.ConclusionsCrystals of β-HMX grown from acetone show good morphological agreement with that predicted by modelling, with three distinct crystal habits observed depending upon the supersaturation of the growth solution. Prismatic habit was favoured at low supersaturation, while tabular and columnar crystals were predominant at higher super saturations. The twin plane in β-HMX was identified as a (101) reflection plane. The low plasticity of β-HMX is shown by the lack of etch pit alignments corresponding to mechanically induced dislocation arrays. On untwinned {010} faces, two types of dislocations exist, pure edge dislocations with b = [010] and pure screw dislocations with b = [010]. On twinned (010) faces, a third dislocation type exists and it is proposed that these pits are associated with pure screw dislocations with b = [010].Graphical abstractEtch pits on the twinned (010) face of β-HMX.

show abstract

Mechanical properties of β-HMX

Cited by 52 publications

References 33 publications

Peierls–Nabarro stresses of dislocations in monoclinic cyclotetramethylene tetranitramine (β-HMX)

Peierls–Nabarro stresses of dislocations in monoclinic cyclotetramethylene tetranitramine (β-HMX)

Prediction of Growth Habit of β-Cyclotetramethylene-tetranitramine Crystals by the First-Principles Models

Growth and dislocation studies of β-HMX

Contact Info

Product

Resources

About