Shock Response of a Heavy Tungsten Alloy

Abstract

_This article describes the results of shock wave experiments performed on a heavy tungsten alloy containing W, Ni, and Fe in the ratio of 92.85:4.9:2.25 by weight. These experiments provide information about the shear strength under compression and tensile strength, as measured by the spall threshold, of this alloy to 24 GPa. The results of these experiments show that: (i) the magnitude of its Hugoniot elastic limit (HEL) is 2.76 + 0.26 GPa; (ii) this alloy deforms plastically above its HEL and thus retains its shear strength to 24 GPa; (iii) the spall strength of the alloy is found to be 1.9 ± 0.4 GPa and is independent of the impact stress and duration of the shock compression pulse; and (iv) the tensile impedance of the alloy, determined from a new experiment designed to measure this impedance, is 68 ± 10 Gg/m s. INTERNATIONAL JOURNAL OF Plasticity PERGAMON AbstractThis article describes the results of shock wave experiments performed on a heavy tungsten alloy containing W, Ni, and Fe in the ratio of 92.85:4.9:2.25 by weight. These experiments provide information about the shear strength under compression and tensile strength, as measured by the spall threshold, of this alloy to 24 GPa. The results of these experiments show that: (i) the magnitude of its Hugoniot elastic limit (HEL) is 2.76 ± 0.26 GPa; (ii) this alloy deforms plastically above its HEL and thus retains its shear strength to 24 GPa; (iii) the spall strength of the alloy is found to be 1.9 ±0.4 GPa and is independent of the impact stress and duration of the shock compression pulse; and (iv) the tensile impedance of the alloy, determined from a new experiment designed to measure this impedance, is 68 ± 10 Gg/m 2 s.

Dynamic fracture of tungsten heavy alloys

“…Dandekar and Weisgerber [2] measured the value of C L ¼ 5.15 mm/ms for the WNiFe alloy. Using that value gives 2.7 GPa for the spall strength of WNiCo and 2.1-2.5 GPa for WNiFe.…”

“…The approach was to measure the spall strength and then conduct a recovery experiment in which the spall strength was barely exceeded. In guiding the experiments, we were aided by measurements of spall strength on similar materials Dandekar and Weisgerber [2] measured a spall strength of 1.7-2 GPa in a 95% WNiFe alloy that had an HEL of 2.8 GPa, and was probably the same as used here. Chang and Choi [3] measured much higher values, 4-5 GPa, in a 90% WNiFe alloy that had an HEL of 3.1 GPa.…”

Recent Progress in Processing of Tungsten Heavy Alloys

“…WHAs such as the one studied here have been studied extensively, primarily as potential materials for KE projectiles [136]. Mechanical properties and physical phenomena at high strain rates have been obtained or observed using Hopkinson bar techniques [137], normal plate impact [138][139][140], and oblique flyer-plate impact [141]. In most of these, the bulk mechanical properties of the homogenized multiphase material (e.g., stress-strain curves and spall strengths) and microstructure such as fracture surfaces or shear localization initiation sites have been reported.…”

“…As for the case of Spalling; dynamic tensile failure in uniaxial strain loading, typically referred to as spall or spallation, frequently occurs in impact events, including the current plate impact experiments [160]. The spall strength of a similar variety of WHA to that currently studied has been measured to be 1.7-2.0 GPa [161]. In a typical spall experiment, impact sends a shock wave or elastic and plastic waves, depending on stress level, through both the target and impactor.…”