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Shaped charge liner (SCL) has been extensively applied in oil recovery and defense industries. Achieving superior penetration capability through optimizing SCL structures presents a substantial challenge due to intricate rate-dependent processes involving detonation-driven liner collapse, high-speed jet stretching, and penetration. This study introduces an innovative optimization strategy for SCL structures that employs jet penetration efficiency as the primary objective function. The strategy combines experimentally validated finite element method with machine learning (FEM-ML). We propose a novel jet penetration efficiency index derived from enhanced cutoff velocity and shape characteristics of the jet via machine learning. This index effectively evaluates the jet penetration performance. Furthermore, a multi-model fusion based on a machine learning optimization method, called XGBOOST-MFO, is put forward to optimize SCL structure over a large input space. The strategy's feasibility is demonstrated through the optimization of copper SCL implemented via the FEM-ML strategy. Finally, this strategy is extended to optimize the structure of the recently emerging CrMnFeCoNi high-entropy alloy conical liners and hemispherical copper liners. Therefore, the strategy can provide helpful guidance for the engineering design of SCL.

This study investigates the enhancement of lateral damage effects after armor penetration by utilizing grooved shaped‐charge liners. Traditional methods often fail to achieve penetration and damage comparable to copper warheads when engaging distant targets or targets with interlayer materials. By modifying the liner structure, the jet can be redirected off‐axis after penetrating the target, improving the overall damage effectiveness. Smooth Particle Hydrodynamics (SPH) simulations were employed to model the fragment cloud damage effects of high‐velocity metal jets from internally grooved liners, and comparisons were made with nongrooved liners. The results show that the fragment clouds generated by grooved liners exhibit greater dispersion angles and velocities than those from nongrooved liners, with groove spacing positively correlated with the divergence angle. SPH simulations align with experimental data, demonstrating that groove spacing and depth significantly influence the primary and secondary perforation areas. Overall, the grooved liner design significantly enhances lateral damage effects, and the consistency between experimental and simulation data further validates its effectiveness. The findings provide new insights and references for improving the postpenetration damage design of shaped‐charge warheads. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Ordnance Equipment Engineering is the property of Chongqing University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Herein, we investigated the effect of W content on the jet penetration performance of W-Cu shaped charge liners by using both simulation and experimental methods. The W-Cu composite liners were prepared directly by using spark plasma sintering (SPS) technique. Microstructural observations showed that W particles were uniformly dispersed within the Cu matrix. The relative density of W-Cu composites decreased slightly from 99.2% to 98.8% with an increase in the W content. The hardness of the W-Cu composite liner increased as increasing W content and reached the highest value of 209.2 HV for the composite reinforced by 60 wt.% W. Besides, the penetration depth increased and reached the maximum value of 80 mm for the composite liner containing 50 wt.% W which is improved by about 11% compared to pure Cu liner. According to simulation and experiment results, the penetration depth of the W-Cu composite liners exhibits a nearly identical trend. W-Cu composite liner containing 50 wt.% W remains the best performance compared to other composites. However, the experimental results are lower compared to the simulation results. This could be because the simulation procedure did not completely account for the actual test conditions. [ABSTRACT FROM AUTHOR]

In this work, a novel five-step cold extrusion forging technology was proposed for fabricating a shaped charge liner with hyperboloid structure feature, in which three steps forming to develop the macroscopic hyperboloid shape and two steps annealing treatments to improve the microstructure and property of the liner. Besides, the preforming process was the focus of this investigation because the size structure, microstructure, and texture of the preform play a crucial role in the manufacture of the final forming process due to the heredity of dimension and microstructure, which also provides powerful process reference with the following forming steps. Based on the ABAQUS finite element (FE) platform, the cold extrusion process of the shaped charge liner preform was simulated, and the influences of forming parameters such as the initial billet size and friction coefficient between billet and dies on forming load, cavity filling, and strain distribution of the preform were investigated, respectively. The simulation results show that the optimal parameters of initial billet diameter and friction coefficient between dies and billet in cold extrusion preforming of shaped charge liner are 50 mm and 0.1, respectively. Additionally, the strain distribution of the shaped charge liner in the cold forming process was analyzed in detail. Finally, the experiment of the cold extrusion of the shaped charge liner preform was carried out to verify the feasibility of the cold extrusion process and the correctness of the simulation results. [ABSTRACT FROM AUTHOR]

Precipitation-hardened high entropy alloys (PHEAs) are promising candidates for shaped charge liners (SCLs) due to their potential in obtaining good penetration depth and diameter. Deformation mechanism under explosive is the key to guiding the alloys microstructure, property optimization and shaped charge designing. In this study, the microstructural evolution and deformation mechanism of PHEA SCLs under explosive loading were systematically investigated. Under explosive loading, both the α 2 and BCC matrix phases underwent dynamic recrystallization, transforming into fine equiaxed grains (∼10 μm). The BCC phase deformed earlier than the α 2 phase, exhibiting a clearly asynchronous deformation behavior. This demonstrates that the α 2 phase can effectively improve the deformation resistance upon detonation and further increase jet diameter. Moreover, the α 2 can be retained under explosive conditions, which enables delaying the expansion of the adiabatic shear bands and further improving the jet continuity. Our results shed lights on developing new high-performance alloys and the related microstructure optimization for engineering applications in SCLs. • Developed a Ti-Zr-Nb-Al PHEA for SCLs, and investigated the deformation mechanism upon detonation loading. • The deformation mechanism of the BCC and α 2 phases was mainly dominated by dynamic recrystallization upon detonation loading. • The BCC and α 2 phases exhibited an obviously asynchronous deformation behavior under explosive loading. [ABSTRACT FROM AUTHOR]

To avoid the aimless design of shaped charge liner (SCL) material for obtaining deep penetration and large penetration holes in reinforced concrete targets, new design principles are proposed in this study. Following the principles, an intermetallic-compound-reinforced Ti-17Al-29Nb alloy was prepared via hot isostatic pressing (HIP) sintering. This alloy shows high dynamic compressive strength (1583 MPa), high dynamic compressive plasticity (35 %), high elevated-temperature tensile strength (414 MPa at 800 °C), and low elevated-temperature plasticity (6 % at 800 °C). The penetrating experiments showed that the Ti-17Al-29Nb alloy liner penetrated through the 600-mm-thick C40 concrete target, forming large penetration holes. Although the penetration depth was slightly lower than that of the most commonly used pure copper liner, the diameter of the exit hole was 2.1 times that of the pure copper liner. The high jet tip velocity (7651 m/s) and large jet diameter (a maximum of 0.28 CD) were the key factors to form the high penetration depth and large penetration hole. This study not only brings a new type of SCL material with excellent penetration performance against reinforced concrete targets but also provides a new research direction for the design and selection of the SCL materials.

The metal injection molding (MIM) method was applied to manufacture a shaped charge liner (SCL) used for petroleum perforating bombs. Its application could overcome the drawback of heterogeneous density distribution prepared using the traditional powder metallurgy and spinning process. The sintering results showed that because of the limitation in the sintering temperature, the relative density of the W–Cu alloy shaped charge liners prepared by metal injection molding (MIM W–Cu SCLs) ranged from 48.05% at 1050 °C to 52.52% at 1100 °C, which was far below those prepared by spinning. Further increase to higher temperature led to the W–Cu separation, cracks, and distortion of the SCL. The explosive test proved that the shaped charge liners prepared by metal injection molding (MIM SCLs) could achieve comparable or even better penetration performance than those prepared by spinning. The particle size of tungsten played a significant role in the penetration performance in which the sample prepared from a −250-mesh tungsten powder showed the highest penetration depth, which was 18.44% deeper than that of the spinning process. From the observation of ballistic holes, the jet of the MIM SCL was composed of dispersed W–Cu particles without a slug. The diameters of the holes bored by the MIM SCLs were larger than those SCLs produced by spinning, which proved that the MIM SCL jet is noncoherent. [ABSTRACT FROM AUTHOR]

To investigate the microstructure evolution and dynamic deformation behavior of a CoCrNi medium entropy alloy under an ultrahigh explosive loading rate, CoCrNi-shaped charged liners were fabricated and fired into steel targets. Targets with residual jet fragments were recovered for detailed microstructural analysis using scanning electrical microscopy, X-ray diffraction, electron backscattered diffraction, and transmission electron microscopy. The results indicate that the grain size was reduced by more than 3 times and grains were found to be equiaxed in the residual jet, which indicates that dynamic recrystallization (DRX) occurred during this extremely high strain rate and large plastic deformation. Furthermore, the content of Cr element in CoCrNi at the grain boundaries increased significantly after detonation deformation. The reduced grain sizes are believed to reduce the bulk diffusion path of Cr from grain interior into grain boundaries with the support of sufficient energy provided by the ultrahigh temperature. The enrichment of Cr at grain boundaries promotes the formation of nanosized Cr-rich precipitates with body-centered cubic (BCC) structures, which were found to be widely distributed along grain boundaries in the residual jet. These precipitates were considered obstacles for grain boundary movement and promotion of crack initiation along the grain boundaries, which might cause ductility loss of the CoCrNi-shaped charge jet and loss of penetration capability. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of High Pressure Physics is the property of Chinese Journal of High Pressure Physics Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The metal injection molding (MIM) method was applied to manufacture a shaped charge liner (SCL) used for petroleum perforating bombs. Its application could overcome the drawback of heterogeneous density distribution prepared using the traditional powder metallurgy and spinning process. The sintering results showed that because of the limitation in the sintering temperature, the relative density of the W–Cu alloy shaped charge liners prepared by metal injection molding (MIM W–Cu SCLs) ranged from 48.05% at 1050 °C to 52.52% at 1100 °C, which was far below those prepared by spinning. Further increase to higher temperature led to the W–Cu separation, cracks, and distortion of the SCL. The explosive test proved that the shaped charge liners prepared by metal injection molding (MIM SCLs) could achieve comparable or even better penetration performance than those prepared by spinning. The particle size of tungsten played a significant role in the penetration performance in which the sample prepared from a −250-mesh tungsten powder showed the highest penetration depth, which was 18.44% deeper than that of the spinning process. From the observation of ballistic holes, the jet of the MIM SCL was composed of dispersed W–Cu particles without a slug. The diameters of the holes bored by the MIM SCLs were larger than those SCLs produced by spinning, which proved that the MIM SCL jet is noncoherent.

To investigate the microstructure evolution and dynamic deformation behavior of a CoCrNi medium entropy alloy under an ultrahigh explosive loading rate, CoCrNi-shaped charged liners were fabricated and fired into steel targets. Targets with residual jet fragments were recovered for detailed microstructural analysis using scanning electrical microscopy, X-ray diffraction, electron backscattered diffraction, and transmission electron microscopy. The results indicate that the grain size was reduced by more than 3 times and grains were found to be equiaxed in the residual jet, which indicates that dynamic recrystallization (DRX) occurred during this extremely high strain rate and large plastic deformation. Furthermore, the content of Cr element in CoCrNi at the grain boundaries increased significantly after detonation deformation. The reduced grain sizes are believed to reduce the bulk diffusion path of Cr from grain interior into grain boundaries with the support of sufficient energy provided by the ultrahigh temperature. The enrichment of Cr at grain boundaries promotes the formation of nanosized Cr-rich precipitates with body-centered cubic (BCC) structures, which were found to be widely distributed along grain boundaries in the residual jet. These precipitates were considered obstacles for grain boundary movement and promotion of crack initiation along the grain boundaries, which might cause ductility loss of the CoCrNi-shaped charge jet and loss of penetration capability.

The paper presents some selected results of tests performed as part of a research task titled "Use of graphene and new multilayer explosive material technologies in shaped charge liner materials". The main aim of the experiments was to test the possibilities of using graphene as an addition to materials used for shaped charge liner production. The primary factors that need to be considered when selecting materials for shaped charge liners are presented. The paper contains a description of the powder materials used, as well as a description of the primary manufacturing steps, encompassing the powder blend preparation, pressing and sintering operations. The results of experiments intended to determine the effects of selected manufacturing process parameters on the porosity of the resulting compacts and sinters are shown, both for products made of pure copper powder and graphene-coated powder. Subsequently, test results for manufacturing of liners made using copper powder pressed using the die and isostatic methods are presented. Liners made of copper powder blends with a varying content of graphene-coated copper powder were also manufactured, and densities and porosities of the resulting sinters were compared.

Copyright of Ordnance Industry Automation is the property of Editorial Board for Ordnance Industry Automation and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A slug prepared from pure titanium shaped charge liners was recovered after detonation deformation at an ultrahigh strain rate over 10 5  s −1 and high strain over 500%. Optical microscopy, electron backscattered diffraction (EBSD), and transmission electron microscopy (TEM) were employed to investigate the microstructure of the Ti shaped charged liner before and after the detonation deformation. The microstructures of the recovered slug include lamellar α grains, equiaxed α grains within localized shear bands, and jagged α grains. EBSD results indicated that the grain orientation distribution is random and no texture was observed in the slug. TEM observation revealed that the α → β → α phase transformation occurred owing to the rapid heating and cooling combined with deformation at ultrahigh strain rates in the Ti shaped charge liner. No melting phenomenon was observed during the deformation process. The deformation process consisted of the explosive detonation stage combined with rapid heating and the subsequent penetration stage combined with rapid cooling. In the explosive detonation stage, the α → β phase transformation instantaneously occurred via a martensitic mechanism. In the penetration stage, the high-temperature slug in β state was cooled rapidly and showed different deformation behaviors in three different areas. [ABSTRACT FROM AUTHOR]

In order to investigate the interaction between shaped charge jet and target, three different targets, including pure copper target, carbon steel target and Ti-6Al-4V alloy target, were penetrated by W-Cu shaped charge jet. Penetration performance and corresponding penetration mechanisms were studied. Calculated theoretical penetration depth ratio of Ti-6Al-4V alloy target, pure Cu target and carbon steel target is 10:2.8:5.7, while the practical penetration depth ratio is 10:28:21, indicating that the interaction between jet and target has a significant effect on the penetration depth. Microstructural analysis shows that the interaction between jet and Cu target is the lightest among the three kinds of targets, leading to an increased penetration depth of Cu target. The interaction between jet and Ti-6Al-4V alloy target is the severest, resulting in an increased transverse energy dissipation of jet and decreased penetration depth of Ti-6Al-4V alloy target. Given the significant interaction between jet and target, we propose a modified equation of penetration depth by adding an empirical parameter, which provides a platform to predict more accurate penetration depth. [ABSTRACT FROM AUTHOR]

The application of reactive materials on shaped charge liners has received much attention. Herein, the demolition mechanism and behavior of reactive materials based shaped charge liner are investigated by experiment, numerical simulation, and theoretical analysis. Three reactive shaped charge liners, composed of a mixture of Al/PTFE (26.5/73.5 wt-%) powders, are fabricated by pressing and sintering. The damage effects of the multi-layered target against reactive materials based shaped charge are investigated. The results show that the reactive liners create excellent collateral damage due to the release of chemical energy contained in reactive materials. An Eulerian computational model is developed to investigate penetration behavior of the reactive jet formed by shaped charge liner. In addition, a theoretical model based on cavity expansion is derived to predict the initiated location of reactive materials. Comprehensive analysis indicates that the TNT equivalence factor for these powder mixtures used in this work is 3.41-7.77 and that the self-delay time is about 0.8 ms. This work will provide guidance and reference for the design of reactive shaped charge liner. [ABSTRACT FROM AUTHOR]

Liners used in shaped charges (SC) must possess good penetration ability and explosive power. Producing the reactive layer (i.e., the Al-Ni composite) on a well-penetrating liner (i.e., Cu) via spray coating is a novel method; the exothermic reaction of this reactive layer can be enhanced by controlling the structure of the feedstock material. However, preceding studies have been unable to completely succeed in achieving this goal. There is still an opportunity to improve the performance of reactive layers in SC liner applications. In order to address this problem, a reactive Al-Ni composite powder was produced via arrested reactive milling (ARM) and deposited by a kinetic spray process. Afterward, the deposition state and self-propagating high-temperature synthesis (SHS) reaction behavior of the ARMed Al-Ni deposit were investigated. The deposition state was degraded by the ARM process due to the remaining solid lubricant and the strain-hardening effect, but the practically estimated bond strength was not poor (~40 MPa). No SHS reactions were induced by the ARM and kinetic spray process, which resulted in the quantitative maximization of the exothermic reaction. It is noteworthy that the initiation temperature of the SHS reaction was highly advanced (~300 °C) relative to preceding studies (~500 °C); this change is due to the additional mechanical activation initiated by the kinetic spray deposition. [ABSTRACT FROM AUTHOR]

Two kinds of W/Cu double-layer shaped charge liner (SCL) were prepared by chemical vapor deposition (CVD) combined with electroforming technique: A SCL with W inner layer and Cu outer layer, B SCL with Cu inner layer and W outer layer. The penetration properties of A and B SCLs were researched. The results show that the two SCLs can form continuous jet and the tip velocities of A and B jets are 7.4 and 6.3 km·s, respectively. The kinetic energy density (5.3 × 10 J·m) of A jet tip increases by 194.4 % compared with that (1.8 × 10 J·m) of B jet tip. B jet, however, exhibits deeper penetration depth at the same experimental conditions. The chemical component and microstructure of the area nearby the ballistic perforation were researched. Component analysis shows that both the jets are formed only from inner layer metal. Microstructure analysis shows that martensite and intermetallic form around ballistic perforation penetrated by A SCL due to the intensive interaction between W jet and steel target. The two kinds of newly formed ultrahard phases also hinder the jet from penetrating target further. As a result of relatively alleviative interaction between Cu jet and target, only solid solution rather than ultrahard phases forms around ballistic perforation penetrated by B SCL. [ABSTRACT FROM AUTHOR]

Explosive experiments of W–Cu–Zn, W–Cu–Ni and W–Cu alloy shaped charge liners (SCLs) were conducted, and the effects of Zn and Ni added in W–Cu alloy on the penetration performance and penetration mechanism of the SCLs were systematically investigated. Results show that Zn and Ni evidently reduce the penetration performance of the SCLs. Microscopic analyses show that the affected zones in the targets are enlarged and the melting of W particles in the jets is aggravated, which indicates the transverse dissipation of the jets energy. Thus, the decreased penetration performance of the SCLs is mainly caused by the severe transverse dissipation of the jets energy. During the penetration process, the addition of Zn in the W–Cu alloy decreases the melting point of the matrix, making the matrix easier to be melted and squeezed out. The lubrication effect of the matrix is reduced severely and the interaction between the W particles and the targets is facilitated. The addition of Ni in the W–Cu alloy increases the melting point of the matrix phase, making the matrix phase harder to be melted and the lubrication effect of the matrix decreased. The reduced lubrication effect leads to severe interaction between the jets and the targets, and the transverse dissipation of the jets energy is aggravated. Moreover, the addition of Ni in the W–Cu alloy increases the bonding strength between the W particles and the matrix, thus during the penetration process, W particles of the W–Cu–Ni jets have severer deformation compared with that of the W–Cu jets. The severer deformation of the W particles leads to further consumption of kinetic energy. [ABSTRACT FROM AUTHOR]

The nanostructured W-Cu powder was prepared by high-energy ball-milling. The W-Cu alloy as liner materials was fabricated by the dynamic consolidation technique. The density of the consolidated sample was 99.6% T.D. The sample was determined by EPMA, and the results show that the composition and the distribution of the elements were uniform. The sample was analyzed by XRD, and the W crystalline sizes were measured as 26 nm. The sample was machined into W-Cu alloy liners, showing good properties of machinability. The armor-piercing experiment of the W-Cu alloy liner of shaped charge without an insulating board indicates that the armor-piercing capability increases by more than 30% in comparison with the copper liner. [ABSTRACT FROM AUTHOR]

The Selective Laser Melting (SLM) technique has attracted attention in a wide range of manufacturing research areas, including the defense industry because of its high efficiency and good consistency of manufactured material properties. Shaped charge liner is the crucial unit in the shaped charge warhead. However, jet performance formed by SLM-produced liner remains to be studied systematically. In the present research work, the SLM technique was applied to manufacture CuSn10 shaped charge liners. Casted CuSn10 liners were also fabricated using the classical turning method for comparison. The grain size of the SLM-produced liner was found to be much smaller than the machined liner due to the rapid heating and cooling rate during the SLM manufacturing process. This contributed to improved jet performance. A flash X-ray photography system was applied to capture jet stretching appearances. Necking appears at the jet tip formed by the machined liner, while the jet formed by the SLM-produced liner remains continuous. Penetration test results show that the penetration depth of the jet formed by the SLM-produced liner is around 27% larger than that formed by the machined liner. Segments along the sidewall of the penetration tunnels were selected for in-depth micro analysis. Energy dispersed spectrum (EDS) surface scanning results indicate the composition at the side wall of the penetrated tunnel. Metallurgical microscope was applied to distinguish four different phase zones of the target. The width of these different zones indicates the severity of the lateral interaction between the jet and target, which can be adopted to evaluate jet penetration capability. The present study analyzes the factors that influence jet performances and proves that SLM technology is well-adapted in the manufacturing of shaped charge liners. [ABSTRACT FROM AUTHOR]

To assess the effect of explosive loading on deformation behavior and microstructure evolution, a slug recovered from a fine-grained copper shaped charge liner after detonation deformation at an ultrahigh strain rate over 104 s−1 was investigated. In the slug, multiple shear bands appeared in a single direction spiral pattern and exhibited self-organization behavior, which constitute the main deformation characteristics. Compared with the initial fine grains, the larger grains formed in the deformed copper liner. The annealing twins and few dislocations were observed in these grains. Further, a copper texture and cube texture appeared in different parts of the slug. The results demonstrate the occurrence of recovery and recrystallization. Throughout the detonation process, a substantial amount of plastic work was transformed into heat, the copper liner underwent rapid heating. The thermal softening due to elevated temperature counteracted work hardening and induced shear localization. The existence of shear bands means that the collapsing mechanism of the liner changed from global deformation to shear localization. Although the post-deformation cooling rate of the slug was very fast, the temperature and time met the requirements of recrystallization and grain growth by grain boundary migration. Through this study, the influence of the thermal effect on ultrahigh strain rate deformation is better understood. • A slug was recovered from a fine-grained Cu SCL after detonation deformation. • The grain size in slug is larger due to sufficient temperature for recrystallization. • The shear bands appeared in slug after the ultrahigh strain rate deformation. • Multiple shear bands in slug show a self-organization characteristic. [ABSTRACT FROM AUTHOR]

An ideally shaped charge warhead is an effective weapon against armored targets. The use of the gathering energy effect generated by the explosion drives the liner to form a shaped charge jet, which can penetrate the armored target. Existing shaped charge warheads often use a metal liner. Herein, we discuss the characteristics of polymer liners. To study the characteristics of the expansive jet formed by the polymer liner, three polymer materials with different properties—polytetrafluoroethylene (PTFE), nylon (PA), and polycarbonate (PC)—were selected. Using the smooth particle hydrodynamics (SPH) method and the AUTODYN finite element software, the expansive jet formation by the polymer liners was simulated and verified by experimental data. The polymer jets of the different materials exhibit a certain degree of expansivity; however, due to differences in the material properties, the expansive diameter of the jet and the degree of head compaction differed. The expansive diameter of the PA jet was the smallest, and that of the PTFE jet was larger than that of the PA jet, but with a smaller compactness. The PC jet exhibited the largest expansive diameter and the highest degree of compactness. [ABSTRACT FROM AUTHOR]

Energetic structural materials (ESMs) have many potential military applications due to their unique functions. In this work, the reactivity and penetration performance of ESMs have been examined as a shaped charge liner material. The penetration experiments of nickel-aluminum (Ni-Al) and copper-nickel-aluminum (Cu-Ni-Al)-shaped charge liners (SCLs) have been designed and fired into 45# steel. The targets were recovered and analyzed by optical microscopy, electron microscopy, energy dispersive spectroscopy, and Vickers microhardness measurements. The head and tail of the crater walls penetrated by two reactive jets demonstrated unique microstructures. The jet rapidly decayed with the penetration process, but the "white" zone (a mixture of martensite and austenite) was more prominent in the tail, and the microhardness of the tail was much higher than that of the head. The results showed the continued exotherm of Ni-Al reactive jet when it was fired into the target. The addition of Cu reduced the exotherm of Ni-Al, Cu could not only increase the average crater size, but also raise the average penetration depth by 42%. These results offer valuable insight for utilizing ESM as shaped charge liner materials. [ABSTRACT FROM AUTHOR]