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 paper, the effect of the deformation rate on the inhomogeneity of the distribution of the slip bands in polycrystalline materials has been investigated, and it has been shown that the plastic deformation is affected by grain boundaries and their vicinity as well as by various orientations of single grains in onephase metals and alloys, and by various component properties in multiphase materials.
Abstract: Considerable local strain differences occur in single crystals as a consequence of slip bands. A significant contribution to this phenomenon is the effect of the deformation rate on the inhomogeneity of its distribution. In polycrystalline materials the plastic deformation is affected by grain boundaries and their vicinity as well as by various orientations of single grains in onephase metals and alloys, and by various component properties in multiphase materials. In some cases it has been possible to describe these phenomena by means of micromechanics. Valuable information has also been acquired by means of three-dimensional stereology.
235 citations
TL;DR: In this paper, the authors established reliable criteria for fabricating B4C-AI particulate composites based on fundamental capillarity thermodynamics, reaction thermodynamics and densification kinetics.
Abstract: The processing problems associated with boron carbide and the limitations of its mechanical properties can be significantly reduced when a metal phase (e.g., aluminum) is added. Lower densification temperatures and higher fracture toughness will result. Based on fundamental capillarity thermodynamics, reaction thermodynamics, and densification kinetics, we have established reliable criteria for fabricating B4C-AI particulate composites. Because chemical reactions cannot be eliminated, it is necessary to process B4C-AI by rapidly heating to near 1200°C (to ensure wetting) and subsequently heat-treating below 1200°C (for microstructural development). [Key words: composites, boron carbide, aluminum, processing, cermets.]
211 citations
TL;DR: In this article, the authors investigated the creep behavior of a Mg-0.8% Al solid solution alloy over the temperature range from 473 to 810 K. The results showed the occurrence of three different mechanisms, with the creep process dependent on the testing temperature and stress level.
207 citations
"Effects of temperature and strain r..." refers background in this paper
...According to Lagneborg,(41) the stress exponent of 4 is common when threshold stress is subtracted from the applied stress in the constitutive relationship, but it can also vary from 3 to 5 depending on the nature of threshold stress.(39,41,42) Such study was not undertaken at this stage....
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TL;DR: In this article, a cost effective and reliable casting technique was introduced to overcome the wetting problem between B 4 C and liquid aluminium metal as well as the formation of undesirable phases at the interface using K 2 TiF 6 flux.
196 citations
25 Aug 2009-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this article, the weldability, microstructure evolution and mechanical properties of an AA6063 aluminium alloy and two composites with AA 6063 matrix reinforced with 6 and 10.5vol.% B4C during friction stir welding are investigated.
Abstract: The weldability, microstructure evolution and mechanical properties of an AA6063 aluminium alloy and of two composites with AA6063 matrix reinforced with 6 and 10.5 vol.% B4C during friction stir welding are investigated. A joint efficiency higher than 60% was obtained and increased to over 80% after artificial ageing. The B4C particles size and shape were not affected by the welding process and the particle distribution in the matrix was kept uniform in the weld zone. Evolution of the aluminium grain structure from coarse grains in the base material to the refined, equiaxed grains in the weld centre is described. The microhardness profiles of various B4C concentration materials were measured in both as-weld conditions and after post-weld heat treatments. Other microstructure changes of Al–B4C MMCs after welding and heat treatment are also reported.
162 citations