Shock Wave Response of Iron-based In Situ Metallic Glass Matrix Composites

Abstract

The response of amorphous steels to shock wave compression has been explored for the first time. Further, the effect of partial devitrification on the shock response of bulk metallic glasses is examined by conducting experiments on two iron-based in situ metallic glass matrix composites, containing varying amounts of crystalline precipitates, both with initial composition Fe49.7Cr17.7Mn1.9Mo7.4W1.6B15.2C3.8Si2.4. The samples, designated SAM2X5-600 and SAM2X5-630, are X-ray amorphous and partially crystalline, respectively, due to differences in sintering parameters during sample preparation. Shock response is determined by making velocity measurements using interferometry techniques at the rear free surface of the samples, which have been subjected to impact from a high-velocity projectile launched from a powder gun. Experiments have yielded results indicating a Hugoniot Elastic Limit (HEL) to be 8.58 ± 0.53 GPa for SAM2X5-600 and 11.76 ± 1.26 GPa for SAM2X5-630. The latter HEL result is higher than elastic limits for any BMG reported in the literature thus far. SAM2X5-600 catastrophically loses post-yield strength whereas SAM2X5-630, while showing some strain-softening, retains strength beyond the HEL. The presence of crystallinity within the amorphous matrix is thus seen to significantly aid in strengthening the material as well as preserving material strength beyond yielding.

Mechanical Properties of an Fe‐Based SAM2×5‐630 Metallic Glass Matrix Composite with Tungsten Particle Additions

“…[6,19] The XRD patterns of the ex situ composites, illustrated in Figure 1b-e, show distinct crystalline peaks corresponding to the tungsten phase, which become more prominent with increasing volume fraction of crystalline tungsten addition into the matrix. Furthermore, tungsten does not alter the SAM2Â5-630 matrix and is consistent with our previous report.…”

“…The higher density is of interest for further improving on the record-breaking shock wave response of SAM2Â5-630 [6] by increasing the shock impedance. The stress-strain curves for SAM2Â5/30%W are linear elastic (without yielding) up to the point of sudden catastrophic failure and typical strain-to-failures are less than 0.2%.…”

“…Simultaneous increase in fracture toughness, hardness, and elastic modulus combined with higher shock impedance due to the addition of the high-density tungsten phase can potentially improve on the record-breaking shock wave response of SAM2Â5-630. [6] The SAM2Â5-630 with 30 vol % tungsten exhibited a characteristic strength and Weibull modulus of 165 and 8.7 MPa, respectively, under 4-point flexure.…”

“…[5] A specific in situ composite of SAM2Â5 (i.e., SAM2Â5-630) has the highest elastic limit during shock impact ever reported for a BMG. [6] Unfortunately, amorphous metals in general suffer from a strong tendency toward shear localization, which leads to low fracture toughness and macroscopically brittle failure at room temperature. [1,[7][8][9][10][11] Phan et al [11] recently presented results from flexure testing of a structurally relaxed SAM2Â5 (i.e., SAM2Â5-600).…”

Suppressing η‐phase development in steel‐cemented tungsten carbide: A spark plasma sintering study

“…The Fe‐cemented composite had a relative density of 99.7% and properties comparable to the Co‐cemented composite. Achieving fast heating rates and short sintering cycles is also possible with spark plasma sintering (SPS), which has been demonstrated for sintering oxides, nonoxides,, and metals …”