A transmission electron microscope study of deformed and fractured commercial grade beryllium

Murr, L. E.; Niou, C. S.; Advani, A. H.; Vega, Laura De la; Stafford, S.W.; Herrera, Juan

doi:10.1016/0921-5093(92)90206-g

Cited by 3 publications

(6 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Rib marks, are present but there are no clear Wallner lines, perhaps adding additional support to the observation that the samples were all very effectively momentum trapped and hence there were no inwardly reflected waves for the crack fronts to interact with. Consistent with literature on quasistatic crack growth in beryllium associated with either failure of a tensile specimen [14,15] or crack propagation of a fracture specimen [16][17][18], the hackle marking can be 01009-p.3 traced back to the origin of crack initiation. Moreover, consistent with this literature, there is no gross transition in fracture mechanism from the area of the initiation and regions of fast crack propagation (such as the mirror to hackle transition typically observed in brittle glasses).…”

Section: Fractographysupporting

confidence: 68%

Characterization of shocked beryllium

Cady

Adams

Hull

et al. 2012

EPJ Web of Conferences

View full text Add to dashboard Cite

Abstract. While numerous studies have investigated the low-strain-rate constitutive response of beryllium, the combined influence of high strain rate and temperature on the mechanical behavior and microstructure of beryllium has received limited attention over the last 40 years. In the current work, high strain rate tests were conducted using both explosive drive and a gas gun to accelerate the material. Prior studies have focused on tensile loading behavior, or limited conditions of dynamic strain rate and/or temperature. Two constitutive strength (plasticity) models, the Preston-Tonks-Wallace (PTW) and Mechanical Threshold Stress (MTS) models, were calibrated using common quasi-static and Hopkinson bar data. However, simulations with the two models give noticeably different results when compared with the measured experimental wave profiles. The experimental results indicate that, even if fractured by the initial shock loading, the Be remains sufficiently intact to support a shear stress following partial release and subsequent shock re-loading. Additional "arrested" drive shots were designed and tested to minimize the reflected tensile pulse in the sample. These tests were done to both validate the model and to put large shock induced compressive loads into the beryllium sample.

show abstract

Section: Fractographysupporting

confidence: 68%

Characterization of shocked beryllium

Cady

Adams

Hull

et al. 2012

EPJ Web of Conferences

View full text Add to dashboard Cite

show abstract

“…The beryllium sample responded nearly linearly to applied tensile stress until roughly 275 MPa, followed by a sharp yield point phenomenon, consistent with previous reports. [1,2,3] In contrast, in compression, the strain response departs from linearity at roughly Ϫ215 MPa with a smoother elastic-plastic transition. In both tension and compression, once plastic deformation is initiated, the samples deform with essentially no hardening.…”

Section: A Macroscopic Responsementioning

confidence: 89%

“…However, we stress that due to our adoption of the initial interplanar spacing as (Eq. [1]) in our analysis of the neutron diffraction data, the thermal intergranular strains are explicitly ignored and the following plots of the intergranular strains reflect only those originating during plastic deformation.…”

Section: A Evolution Of Intergranular Strains With Plastic Deformationmentioning

confidence: 99%

“…[2,3] However, Murr et al saw little evidence of dislocation pinning and asserted that plastic deformation was dominated by localized slip at the grain boundaries. [1] Relatively few studies of uniaxial compressive deformation of polycrystalline beryllium exist, [8][9][10][11] and only those in References 10 and 11 concentrated on hot-pressed material. The upper/lower yield point phenomena reported in tension are not observed for hot-pressed beryllium in compression.…”

Section: Introductionmentioning

confidence: 99%

“…[1][2][3][4][5][6][7] In tension, hotpressed beryllium typically exhibits a sharp yield point phenomenon, with upper and lower yield points between 325 and 275 MPa, respectively, with an elongation of 0.7 to 3 pct depending on the impurities, heat treatment, and grain size. [2,4,6,7] This yield phenomenon in beryllium has been attributed to dislocation pinning by iron-bearing precipitates.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A neutron diffraction and modeling study of uniaxial deformation in polycrystalline beryllium

Brown

Bourke

Tomé

et al. 2003

Metall Mater Trans A

View full text Add to dashboard Cite

The deformation of polycrystalline beryllium to strains of Ϯ0.8 pct in uniaxial tension and compression was studied by neutron diffraction and modeled using an elasto-plastic self-consistent (EPSC) model. The beryllium response is asymmetric with respect to tension and compression in both the macroscopic behavior, as displayed in the stress/strain curve, and the microscopic lattice response. The EPSC model qualitatively reproduces the lattice strain curves in tension and compression with the assumption of pyramidal slip being active, in addition to prism and basal slip and with the inclusion of thermal residual stresses developed during processing. Although it underpredicts the magnitude of the observed strains, it demonstrates that accounting for residual stresses of thermal origin is crucial for understanding the evolution of lattice strains during uniaxial loading.

show abstract