Effects of temperature and strain rate on compressive flow behavior of aluminum-boron carbide composites
TL;DR: In this article, the authors investigated the flow properties of aluminum and aluminum-boron carbide (Al-B4C) composites, containing 5, 10 and 15 wt% B4C, at compression tests at strain rates of 10−4, 10−3 and 10−2 s−1 over the temperature range 25 to 500℃.
Abstract: Flow properties of aluminum and aluminum-boron carbide (Al-B4C) composites, containing 5, 10 and 15 wt% B4C, were investigated by compression tests at strain rates of 10−4, 10−3 and 10−2 s−1 over the temperature range 25 to 500℃. The nature of stress–strain curves as a function of reinforcement, temperature and strain rate revealed that (1) flow stress initially increases as the reinforcement increases, but it decreases for Al-15% B4C composite, (2) flow stress increases with the increase in strain rate, with the strain rate sensitivity index varying from 0.01 for aluminum at 200℃ to 0.30 for Al-5% B4C composite. The activation energy for deformation is found to vary from 124 to 187 kJ/mol for Al-15% B4C and Al-5% B4C composites, respectively.
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TL;DR: Microstructure evolution of 15'wt% boron carbide particle reinforced aluminum matrix composites (B4C/Al composites) with titanium addition during liquid-stirring process was dynamically characteriz...
Abstract: Microstructure evolution of 15 wt% boron carbide particle reinforced aluminum matrix composites (B4C/Al composites) with titanium addition during liquid-stirring process was dynamically characteriz...
32 citations
11 Mar 2019-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this article, the deformation behavior of a rolled Al-15vol% B4C composite was studied at high temperatures, using single tensile tests over a wide range of strain rates.
Abstract: Deformation behavior of a rolled Al-15 vol% B4C composite was studied at high temperatures, using single- tensile tests over a wide range of strain rates. The deformation of the composite is characterized by high apparent stress exponent, na and high activation energy, Qa, which are higher than those reported in pure Al. The analysis showed the presence of threshold stress that its value increases with decreasing the testing temperature. Using the threshold stress in the analysis, the obtained values of the true stress exponents, nt of ~ 5 and the true activation energy, Qt of 130 kJ mol−1, were similar to those reported for pure Al. TEM results of subgrain formation along with the mechanical data (nt and Qt) suggest that dislocation climb in the Al matrix is the rate controlling mechanism. The elongation (ef %) showed a maximum value at 500 °C at intermediate value of Zener-Hollomon parameter, Z. The fracture surfaces of tested samples are characterized by mixed modes of ductile (dimple formation) and brittle (cleavage) failures, which were dependent on the deformation conditions of temperature and strain rate.
15 citations
TL;DR: In this paper, the authors investigated the tensile flow behavior of aluminum-boron carbide (Al-B4C) composites of 0, 5 and 15% B4C, hot rolled to ~88% with intermediate annealing at 350°C, and found that the strain rate sensitivity index (m) was found to be ~0.1 over for all the composites in both as-cast as well as hot rolled condition.
Abstract: High temperature tensile flow behavior of aluminum-boron carbide (Al-B4C) composites of 0, 5 and 15% B4C, hot rolled to ~88% with intermediate annealing at 350 °C, was investigated by constant initial strain rate (CIS) test technique at 500 °C and strain rate jump test technique over the temperature range of 400–500 °C. In the as-cast condition, the flow stresses obtained between CIS and strain rate jump test techniques were found to be significantly different at 500 °C. The strain rate sensitivity index (m) was found to be ~0.1 over for all the composites in both as-cast as well as hot rolled condition. Tensile elongations were found to be 0.36 in both as-cast and hot rolled aluminum, whereas the same reduced in Al-5% B4C composite to 0.35 and 0.27, respectively. The values of activation energy (Q) for deformation of rolled aluminum and Al-5% B4C composite were determined to be 194.2 and 73.4 kJ/mol, respectively. The microstructural examination, using SEM and EBSD techniques, revealed cavitation in alum...
4 citations
01 Jun 2020
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TL;DR: In this article, different volume fractions of B4C particles were incorporated into the aluminum alloy by a mechanical stirrer, and squeeze-cast A356 matrix composites reinforced with B4c particles were fabricated.
Abstract: In this study, different volume fractions of B4C particles were incorporated into the aluminum alloy by a mechanical stirrer, and squeeze-cast A356 matrix composites reinforced with B4C particles were fabricated. Microstructural characterization revealed that the B4C particles were distributed among the dendrite branches, leaving the dendrite branches as particle-free regions in the material. It also showed that the grain size of aluminum composite is smaller than that of monolithic aluminum. X-ray diffraction studies also confirmed the existence of boron carbide and some other reaction products such as AlB2 and Al3BC in the composite samples. It was observed that the amount of porosity increases with increasing volume fraction of composites. The porosity level increased, since the contact surface area was increased. Tensile behavior and the hardness values of the unreinforced alloy and composites were evaluated. The strain-hardening behavior and elongation to fracture of the composite materials appeared very different from those of the unreinforced Al alloy. It was noted that the elastic constant, strain-hardening and the ultimate tensile strength (UTS) of the MMCs are higher than those of the unreinforced Al alloy and increase with increasing B4C content. The elongation to fracture of the composite materials was found very low, and no necking phenomenon was observed before fracture. The tensile fracture surface of the composite samples was indicative of particle cracking, interface debonding, and deformation constraint in the matrix and revealed the brittle mode of fracture.
80 citations
"Effects of temperature and strain r..." refers background in this paper
...3 It is estimated that nearly 69% of annual Metal Matrix Composites (MMCs) produced are Al matrix-reinforced composites.(4) Boron carbide (B4C), also called as black diamond, is a promising covalently bonded ceramic material used as reinforcement in Al matrix....
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15 Dec 2010-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: The average grain size of the accumulative roll bonding (ARB) processed composite was about 186nm by linear intercept method, based on transmission electron microscopy (TEM) observations.
Abstract: In the present study, Al/B 4 C composites were produced and compared in the form of sheets, through accumulative roll bonding (ARB) and repeated roll bonding (RRB) processes. The microstructure of the composites fabricated by both the methods, revealed by scanning electron microscopy (SEM), showed the B 4 C particles properly distributed in the aluminum matrix. The average grain size of the ARB processed composite was about 186 nm by linear intercept method, based on transmission electron microscopy (TEM) observations. Mechanical properties of the Al/B 4 C composites produced by two methods were investigated by tensile and hardness tests. The results showed that the tensile strength and hardness of the ARB and RRB processed composites increase with the number of cycles. However, the tensile strength and hardness of the ARB processed composite are much higher than those of the RRB processed composite. The tensile test results revealed that the elongation of the ARB processed composite is lower than that of the RRB processed composite.
73 citations
TL;DR: In this article, a composite material consisting of an Al-12Si matrix reinforced with 20% B 4 C particles was used to produce hard and dense composite coatings with good cohesion between the deformed particles and good adhesion to the substrate.
Abstract: Coatings of a composite material consisting of an Al–12Si matrix reinforced with 20 wt.% B 4 C particles were produced using Cold Gas Dynamic Spray (CGDS) and Pulsed Gas Dynamic Spray (PGDS) processes onto Al-6061 and SS-316L substrates. Two types of composite feedstock powders (mechanically mixed and cryomilled) were used. The influence of the coating process as well as the nature of the feedstock material on the coating microstructure and mechanical properties was studied. The combination of cryomilling to synthesize the feedstock powder and the spray processes provides a unique opportunity to produce hard and dense composite coatings with good cohesion between the deformed particles and good adhesion to the substrate, no phase degradation, very low compressive stresses and high dry sliding wear resistance. The two spray processes have shown almost similar results regarding microstructure and mechanical properties. No effect of the substrate material, Al-6061 and SS-316L, on the coating microstructure and properties was observed.
72 citations
TL;DR: In this paper, the grain structure in the matrix of B 4 C particulate reinforced MMCs and their friction stir welds is characterized by using optical metallography and the electron backscatter diffraction (EBSD) technique.
70 citations
TL;DR: In this article, the microstructure of matrix/reinforcement interface was investigated using SEM studies with or without Ti added composites, and the reaction layer was also characterized with EDS analysis and X-ray mapping.
Abstract: In the present work, Al-B4C composites were produced by casting route at 850°C and titanium-containing flux was used to overcome the wetting problem between B4C and liquid aluminium metal. The microstructure of matrix/reinforcement interface was investigated using SEM studies with or without Ti added composites. The reaction layer was also characterized with EDS analysis and X-ray mapping. It was found from the microstructural observations by high resolution field emission gun SEM (FEG-SEM) that the wetting issue was effectively solved by the formation of very thin (80-180 nm in thickness) Ti-C and Ti-B reaction layers.
59 citations