Ballistic performance of tungsten particle/metallic glass matrix composite long rod

In the present manuscript numerical analysis on the ballistic performance of a tungsten particle/metallic glass matrix(WP/MG) composite rod is conducted by integrating with related experimental investigations. In the corresponding finite element method(FEM) simulations a modified coupled thermomechanical constitutive model is employed to describe the mechanical properties of metallic glass(MG)matrix, and geometrical models of the WP/MG composite rod are established based on its inner structure. The deformation and failure characteristics of the rod and target materials are analyzed in detail,and the influences of various factors on the ballistic performance of the WP/MG composite long rod are discussed. Related analysis demonstrates that the penetrating performance of the WP/MG rod is similar to that of the tungsten fiber/metallic glass matrix(WF/MG) composite long rod, i.e., a "self-sharpening" behavior also occurs during the penetration process, and correspondingly its penetrating capability is better than that of the tungsten heavy alloy(WHA) rod. However, the mass erosion manner of the WP/MG rod is different and the erosion is relatively severe, thus its penetrating capability is a little lower compared with that of the WF/MG one. Moreover, the impact velocity and the target strength have significant influences on the ballistic performance of the WP/MG composite rod, whereas the effect of initial nose shape is very little.

Probabilistic Modelling of Microstructural Evolution in Zr Based Bulk Metallic Glass Matrix Composites during Solidification in Additive Manufacturing

Bulk metallic glass and their composites (BMGMCs) are a new class of materials which possess superior mechanical properties as compared to existing conventional materials. Owing to this, they are potential candidates for tomorrow’s structural applications. However, they suffer from poor ductility and little or no toughness which render them brittle and they manifest catastrophic failure under applied force. Their behavior is dubious, unpredictable and requires extensive experimentation to arrive at conclusive results. In present study, an effort has been made to design bulk metallic glass matrix composites by the use of modeling and simulation. A probabilistic cellular automaton (CA) model is developed and described in present study by author which is used in conjunction with earlier developed deterministic model to predict microstructural evolution in Zr based BMGMCs in additive manufacturing liquid melt pool. It is elaborately described with an aim to arrive at quantitative relations which describe process and steps of operations. Results indicate that effect of incorporating all mass transfer and diffusion coefficients under transient conditions and precise determination of probability number play a vital role in refining the model and bringing it closer to a level that it could be compared to actual values. It is shown that proposed tailoring can account for microstructural evolution in metallic glasses.

Fiber Traction Printing:A 3D Printing Method of Continuous Fiber Reinforced Metal Matrix Composite

A novel metal matrix composite freeform fabrication approach,fiber traction printing(FTP),is demonstrated through controlling the wetting behavior between fibers and the matrix.This process utilizes the fiber bundle to control the cross-sectional shape of the liquid metal,shaping it from circular to rectangular which is more precise.The FTP process could resolve manufacturing difficulties in the complex structure of continuous fiber reinforced metal matrix composites.The printing of the first layer monofilament is discussed in detail,and the effects of the fibrous coating thickness on the mechanical properties and microstructures of the composite are also investigated in this paper.The composite material prepared by the FTP process has a tensile strength of 235.2 MPa,which is close to that of composites fabricated by conventional processes.The complex structures are printed to demonstrate the advantages and innovations of this approach.Moreover,the FTP method is suited to other material systems with good wettability,such as modified carbon fiber,surfactants,and aluminum alloys.

Mg-Cu-Zn-Y-Zr bulk metallic glassy composite with high strength and plasticity

Mg65Cu20Zn5Y9Zr1 bulk metallic glass matrix composite with a diameter of 2 mm was produced by copper mold casting. Upon cooling the Mg65Cu20Zn5Y9Zr1 melt, Mg2Cu acicular crystalline phase precipitates uniformly with a size of about 20 μm long and 1 μm thick while the remaining melt undergoes glass transition. Room temperature compression tests revealed that the high fracture strength up to 830 MPa and the plastic strain of 2.4% before failure are obtained for the Mg-based bulk metallic glass matrix composite. The formation of the Mg2Cu phase was proposed to contribute to high strength and plastic deformation of the material.

Effects of heat treatment on mechanical properties and microstructure of tungsten fiber reinforced grey cast iron matrix composites

In this study,grey cast iron matrix composites reinforced by different volume fractions of tungsten fibers(Vr=0.95%,1.90%,2.85%,3.80%)were investigated in as-cast and under the heat treatment temperatures of 1,000℃and 1,100℃.The microstructure and mechanical properties of the composites were analyzed and tested by means of SEM,micro-hardness tester and three-point bend testing.The results show that with increasing of the volume fraction of tungsten fibers,the composites reinforced by the tungsten fiber have higher flexural strength and modulus than that of cast iron without reinforcement,and the flexural strength increases with the increasing of heat treatment temperatures.Due to diffusion reaction between matrix and reinforcing phases,the process of heat treatment,the number of graphite flakes in the matrix seemingly becomes lower;and some hard carbide particles are formed around the residual tungsten fibers.Not only does the hardness of both matrix and reinforcement change tremendously,but also the region of reinforcement is also extended from the original 0.11 mm to 0.19 mm in radius.

Prediction of the Elastic Properties of Short Basalt Fiber Reinforced Al Alloy Metal Matrix Composites

In this paper, a micro-mechanical model is implemented in software for the prediction of local mechanical properties of discontinuous short fiber reinforced composites. The model, based on the Mori and Tanaka method, shear-lag, computational model, Nielsen-Chen model and Miwa’s model is used to predict the elastic behaviour of basalt short fiber reinforced with Al alloy composites. The Al/basalt Metal Matrix Composites (MMCs) contain basalt short fiber from 2.5% to 10% in steps of 2.5 wt.% and are fabricated using squeeze infiltration technique. The effects of fiber length and orientation on elastic properties of Al/basalt MMCs are investigated. A comparison between the experimental data and the theoretical data based on physical models is made, and the significance of the findings is discussed. The results show that as short basalt fiber content was increased from 2.5% to 10% by wt.%, an improvement in Young’s modulus of 13.26% has been observed. Optical microscopy was used to examine the general microstructure and fiber distribution in the composite produced. Scanning Electron Microscopy (SEM) was performed on the fractured surface to understand the failure mechanisms.

An Application of the Modified Shear Lag Model to Study the Influence of Thermal Residual Stresses on the Stiffness and Yield Strength of Short Fiber Reinforced Metal Matrix Composites

The modified shear lag model proposed recently was applied to calculate thermal residual stresses and subsequent stress distributions under tensile and compressive loadings. The expressions for the elastic moduli and the yield strengths under tensile and compressive loadings were derived which take account of thermal residual stresses. The asymmetries in the elastic modulus and the yield strength were interpreted using the derived expressions and the obtained results of the stress calculations. The model predictions have exhibited good agreements with the experimental results and also with the other theoretical predictions

Wear resistance of surface metal matrix composite produced by gas tungsten arc melt injection of Cr3C2 -NiCr particles into low carbon steel

Cr3 C2-NiCr particles were injected into the melted surface of Q235 low carbon steel to make a surface metal matrix composite （MMC） layer by gas tungsten are melt injection （GTAMI） process. Hardness of the surface MMC layer was tested. Wear resistance of the surface MMC was investigated with a ball-on-disk dry sliding setup. Microstrnetures of the surface MMC layer and morphology of the worn surfaces were investigated with scanning electron microscopy （SEM）. The results showed that the hardness of the MMC was as high as 1 960. 7 HV. Wear loss of the upper part of the MMC layer is onlyO. 8% of that of the substrate under the dry sliding condition given. Wear loss of the bottom part is 2. 5 % of that of the substrate.

Preparation of tungsten-particle-reinforced Zr-based bulk metallic glass composites by two-step spark plasma sintering:microstructure evolution,densification mechanism and mechanical properties

A new two-step spark plasma sintering(TSS)process with low-temperature pre-sintering and high-temperature final sintering has been successfully applied to prepare the tungsten-particle(Wp)-reinforced bulk metallic glass composites(Wp/BMGCs).Compared to normal spark plasma sintering(NS),the densification rate and relative density of Wp/BMGCs can be improved by selecting TSS with appropriate sintering pressure in the low temperature pre-sintering stage.However,the compressive strength and plastic strain of 30%Wp/BMGCs prepared by TSS are both higher than those of the samples prepared by NS.The TSS process can significantly enhance the compressive strength of 30%Wp/BMGCs by 12%and remarkably increase the plastic strain by 50%,while the trend is completely opposite for 50%Wp/BMGCs.Quasi-in situ experiments and finite element simulations reveal that uneven temperature distribution among particles during low-temperature pre-sintering causes local overheating at contact points between particles,accelerating formation of sintering neck between particles and plastic deformation of Wp.When the volume fraction of Wp is low,TSS can improve the interface bonding between particles by increasing the number of sintering necks.This makes the fracture mode of Wp/BMGCs being predominantly transgranular fracture.However,as the volume fraction of Wp increases,the adverse effects of Wp plastic deformation are becoming more and more prominent.The aggregated Wp tends to form a solid"cage structure"that hinders the bonding between particles at the interface;correspondingly,the fracture behavior of Wp/BMGCs is mainly dominated by intergranular fracture.Additionally,reducing the sintering pressure during the low-temperature pre-sintering stage of TSS has been shown to effectively decrease plastic deformation in Wp,resulting in a higher degree of densification and better mechanical properties.

A New Modification to Shear Lag Model as Applied to Stiffness and Yield Strength of Short Fiber Reinforced Metal Matrix Composites

A new modification for the shear lag model is given and the expressions for the stiffness and yield Strength of short fiber metal matri×composite are derived. These expressions are then compared with our experimental data in a SiCw/Al-Li T6 composite and the published experimental data on different SiCw/Al T6 composites and also compared with the previous shear lag models and the other theoretical models.

Fabrication and thermal conductivity of copper matrix composites reinforced by tungsten-coated carbon nanotubes

Carbon nanotubes （CNTs） were coated by tungsten using metal organic chemical vapor deposition. Magnetic stirring was employed to disperse the W-coated CNTs （W-CNTs） in a Cu matrix, and then, the mixed powders were consolidated by spark plasma sintering. The W-CNTs obtained a uniform dispersion within the Cu matrix when the W-CNT content was less than 5.0vo1%, but high content of W-CNTs （10vol%） resulted in the presence of clusters. The W-CNT/Cu composites containing low content of W-CNTs （〈5.0vol%） exhibited a higher thermal conductivity than the sintered pure Cu, while the CNT/Cu composites exhibited no increase in thermal conductivity after the incorporation of uncoated CNTs. The W-CNT content was found to play a crucial role in determining the thermal conductivity of the W-CNT/Cu composites. The thermal conductivity of the W-CNT/Cu composites increased first and then decreased with the W-CNT content increasing. When the W-CNT content was 2.5vo1%, the W-CNT/Cu composite obtained the maximum value of thermal conductivity. The thermal resistance of the （W-CNT）-Cu interface was predicted in terms of Maxwell-Gamett effective medium approximation, and its calculated value was about 3.0× 10-9 m2.K.W-l.

Microstructure and Mechanical Properties of as Cast Aluminium Alloy 7075/Basalt Dispersed Metal Matrix Composites

This paper aims to study the effects of short basalt fiber reinforcement on the mechanical properties of cast aluminium alloy 7075 composites containing short basalt fiber of content ranging from 2.5 to 10 percent by weight in steps of 2.5 percent and fabricated using compo-casting technique. The objective is to investigate the process feasibility and resulting material properties such as young’s modulus, ductility, hardness & compression strength. The properties obtained are compared with those of as-cast that were manufactured under the same fabrication conditions. The results of this study revealed that, as the short basalt fiber content was increased, there were significant increases in the ultimate tensile strength, hardness, compressive strength and Young’s modulus, accompanied by a reduction in its ductility. Furthermore, the microstructure & facture studies were carried out using Optical Microscopy (OM) and Scanning Electron Microscopy (SEM) in order to establish relationships between the quality of the fiber/aluminium interface bond and hence to link with mechanical properties of the composites.

Micro-yield behaviors of Al_2O_3-SiO_(2(sf))/Al-Si metal matrix composites

Effects of the volume fraction and the size of crystallized alumina silicate short fibers as well as heat treatment processes on micro-yield strength(MYS) of Al2O3-SiO2(sf)/Al-Si metal matrix composite(MMC) that was fabricated by squeezing cast, were investigated by using continuous loading method on an Instron 5569 tester with a special extensometer with an accuracy of 10?7. The results show that MYS of MMC decreases with the increase of volume fraction and length of the alumina silicate short fibers in the metal matrix composite, respectively. MYS of quenched Al2O3-SiO2(sf)/Al-Si MMC is the lowest, MYS of the MMC through peak-aging treatment is higher than that through other heat treatment methods. And before the peak-aging, MYS of MMC aging treated gradually increases with the increase of the aging time. Aging treatment after solution treatment is a preferred way that enhances micro and macro-yield strength of Al2O3-SiO2(sf)/Al-Si MMC.

Fabrication and Characterization of Glass Fiber with SiC Reinforced Polymer Composites

Glass Fiber Reinforced Polymeric (GFRP) Composites are most commonly used as bumpers for vehicles, electrical equipment panels, and medical devices enclosures. These materials are also widely used for structural applications in aerospace, automotive, and in providing alternatives to traditional metallic materials. The paper fabricated epoxy and polyester resin composites by using silicon carbide in various proportions along with GFRP. The hand lay-up technique was used to fabricate the laminates. To determine the properties of fabricated composites, the tensile, impact, and flexural tests were conducted. This method of fabrication was very simple and cost-effective. Their mechanical properties like yield strength, yield strain, Young’s modulus, flexural modulus, and impact energy were investigated. The mechanical properties of the GFRP composites were also compared with the fiber volume fraction. The fiber volume fraction plays a major role in the mechanical properties of GFRP composites. Young’s modulus and tensile strength of fabricated composites were modelled and compared with measured values. The results show that composites with epoxy resin demonstrate higher strength and modulus compared to composites with polyester resin.

INFLUENCE OF FIBER COATING ON TENSILE BEHAVIOR OF UNIDIRECTIONAL C/Mg COMPOSITES

The mechanical properties and deformation mechanisms of unidirectional carbon fiber reinforced magnesium composites under tensile loading are studied. Two different materials are used as fiber coatings: a single silica and a gradient C/SiC/SiO[sb 2]. The results show that, under the same preparation conditions, composite with the former coating is broken in a non-cumulative mode and its failure stress is rather low. Conversely, the latter coating demonstrates much better efficiency and the corresponding composite is broken in a cumulative mode.

C/Ti/Cu interfacial reaction in SiCf/Cu composites

Continuous SiC fiber reinforced copper matrix （SiC~/Cu） composites were prepared by fiber coating method, and Ti6A14V interlayer was introduced as an interfacial modification coating to improve the interfacial bonding strength. The interfacial reaction characteristics were investigated by transmission electron microscopy （TEM）. The results show that nearly all the titanium atoms reacted with the carbon coating of SiC fibers to form two layers of TiC. Also, a thin copper layer that is sandwiched between these two layers was detected. No Ti-Cu interfacial reaction product was observed. The formation process of the interfacial reaction along with its mechanism was discussed.

Corrosion Behavior of Fe-based Bulk Metallic Glass and In-situ Dendrite-reinforced Metallic Glass Matrix Composites in Acid Solution

The corrosion behavior study was conducted on a novel Fe77 Mo5P9C7.5 B1.5 in-situ metallic glass matrix composite （MGMC）. This composite sample was developed by introduction of bcc a-Fe dendrites as reinforcing phase. The corrosion behavior of this composite was compared to its monolithic counterpart and other Fe-based alloys such as 304L and 2304L stainless steels. The corrosion resistance of MGMCs in H2SO4 solution shows inferior to that of other Fe-based alloys. Experiments suggest that Fe-BMGs samples possess better corrosion resistance property than that of Fe-MGMCs. The possible underlying reasons can be the inhomogeneity induced by the precipitation of a-Fe dendrites in the MGMCs.

Effect of Cu content on microstructure and mechanical properties of in-situ β phases reinforced Ti/Zr-based bulk metallic glass matrix composite by selective laser melting(SLM)

In this study,non-toxic in-situβphases of reinforced Ti/Zr-based bulk metallic glass matrix composites(BMGCs)of(Ti_(0.65)Zr_(0.35))100-xCux(x=5,10,15 at.%)are fabricated via selective laser melting.The effect of Cu content on phase formation,microstructure,and mechanical properties is investigated.The average volume fraction and width of theβphase decreases with increasing Cu content,while a more amorphous phase and the(Ti,Zr)_(2)Cu phase forms.In the center zone of the molten pool,theβphase grows in the direction of the temperature gradient,and the amorphous phase distributes among theβphases.This occurs using:sphere morphology(for x=5),a more continuous elongated sphere and network morphology(for x=10),and network morphology(for x=15),respectively.In the edge zone of the molten pool,due to the smaller cooling rate and the existence of a partially molten zone,theβphase becomes coarser,and an amorphous phase forms for more continuous networks.Furthermore,the hardness improves significantly with increasing Cu content.No crack is found for x=5.Although the average volume fraction of theβphase for x=5 is about 90%,the compression yield strength is 1386±64 MPa,reaching to an average level of conventionally fabricated counterparts,due to finer microstructure,and twinning and martensitic transformation of theβphase.

CuZr-based bulk metallic glass and glass matrix composites fabricated by selective laser melting

Monolithic bulk metallic glass and glass matrix composites with a relative density above 98%were produced by processing Cu_(46)Zr_(46)Al_(8)(at.%)via selective laser melting(SLM).Their microstructures and mechanical properties were systematically examined.B2 CuZr nanocrystals(30-100 nm in diameter)are uniformly dispersed in the glassy matrix when SLM is conducted at an intermediate energy input.These B2 CuZr nanocrystals nucleate the oxygen-stabilized big cube phase during a remelting step.The presence of these nanocrystals increases the structural heterogeneity as indirectly revealed by mircrohardness and nanoindentation measurements.The corresponding maps in combination with calorimetric data indicate that the glassy phase is altered by the processing conditions.Despite the formation of crystals and a high overall free volume content,all additively manufactured samples fail at lower stress than the as-cast glass and without any plastic strain.The inherent brittleness is attributed to the presence of relatively large pores and the increased oxygen content after selective laser melting.