摘要 :
A novel high-strength die-cast Al-Si-Cu-Mg alloy has been developed in the present work. Experimental results indicated that the combination of different amounts of 0-Al_2Cu and Q-Al_5Cu_2Mg_8Si_6 phases could provide a same yield...
展开
A novel high-strength die-cast Al-Si-Cu-Mg alloy has been developed in the present work. Experimental results indicated that the combination of different amounts of 0-Al_2Cu and Q-Al_5Cu_2Mg_8Si_6 phases could provide a same yield strength but different elongations due to the differences in size and distribution of these two phases. By optimizing the synergistic strengthening of Q-Al_5Cu_2Mg_8Si_6 and θ-Al_2Cu phases, the balanced strength-ductility trade-off was achieved at 3.0 wt% Cu and 0.9 wt% Mg, offering a yield strength of 225 MPa and an elongation of 4.3% under as-cast condition. Except the normal Q and 9 large lamellar or blocks located in n-Al grain boundary, numerous nanoscale Q-Al_5Cu_2Mg_8Si_6 precipitates (mostly under 200 nm) were also observed inside the α-Al grains in the newly developed alloy. Thermodynamic calculation was performed using Pandat 2018 software to explain the formation and distribution of strengthening phases. It was found that Q-Al_5Cu_2Mg_8Si_6Si6 can be precipitated from (1) the melt directly via liquid-solid reaction and (2) α-Al phase via solid-solid reaction. The nanoscale Q-Al_5Cu_2Mg_8Si_6 particles are considered to be precipitated via the latter solid reactions.
收起
摘要 :
An in-situ dual morphology Ti_8C_5/TiB_2 reinforced TiAl composite (DMTTC) is prepared by adding the inoculant which is prepared by spark plasma sintering (SPS). In DMTTC, Ti_8C_5 whiskers/nanoparticles and TiB_2 nano-particles ha...
展开
An in-situ dual morphology Ti_8C_5/TiB_2 reinforced TiAl composite (DMTTC) is prepared by adding the inoculant which is prepared by spark plasma sintering (SPS). In DMTTC, Ti_8C_5 whiskers/nanoparticles and TiB_2 nano-particles have a synergistic strengthening effect on TiAl alloy. In addition, this paper further discusses the synergistic strengthening mechanism of DMTTC.
收起
摘要 :
Aggregation and weak interfacial bonding limit the superior strengthening potential of the carbon nanotubes (CNTs) in the metal matrix composites. To overcome these challenges, in situ Mg2Si nanoparticles (Mg2Sip) have been hybrid...
展开
Aggregation and weak interfacial bonding limit the superior strengthening potential of the carbon nanotubes (CNTs) in the metal matrix composites. To overcome these challenges, in situ Mg2Si nanoparticles (Mg2Sip) have been hybridized with surface modified CNTs through chemical oxidization. The synergistic strengthening was enhanced by tailoring the volume ratios of CNTs to Mg2Sip in the Mg matrix through powder thixoforming technology. Herein, when 0.3CNTs-1.2Mg(2)Si(p) was added, a yield strength, ultimate tensile strength, and elongation of 213 MPa, 271 MPa, and 6.3%, respectively, were obtained, which were 18.3%, 16.8%, and 3.3% higher than those of the 0.75CNTs-0.75Mg(2)Si(p)/Mg composites, respectively. The strengthening effects of the CNTs-Mg2Sip reinforcements were more effective than those of the individual 1.5CNTs and 1.5Mg(2)Si(p) owing to the effective thermal mismatch and load transfer strengthening mechanisms. In this study, we propose an effective approach to harness the superior performances of the hybrid reinforcements for enhancing the composites. (C) 2020 Elsevier B.V. All rights reserved.
收起
摘要 :
The hot rolled medium manganese Ti-bearing and Ti-free steels were solution treated at 1000℃ and then aged at 500, 550 and 600℃, respectively. The results showed that Ti-bearing steel had refined grain size but higher hardness t...
展开
The hot rolled medium manganese Ti-bearing and Ti-free steels were solution treated at 1000℃ and then aged at 500, 550 and 600℃, respectively. The results showed that Ti-bearing steel had refined grain size but higher hardness than Ti-free steel. Moreover, Ti-bearing steel exhibited a superior impact toughness than Ti-free steel, especially when the samples were aged at 500℃, which was attributed to the homogeneous distribution of Ti(C, N) precipitates and alloyed cementite in the matrix. In addition, the Ti-bearing steel aged at 500℃ exhibited the best wear resistance despite its lower initial hardness, which was primarily attributed to the significant work hardening achieved by ε-martensitic transformation and mechanical twins during wear deformation.
收起
摘要 :
A medium-carbon martensitic mold steel with high strength and toughness is obtained based on the synergistic effect of nano precipitates and fine-grained (FG) structure. Treatment increases the length per unit area of the effectiv...
展开
A medium-carbon martensitic mold steel with high strength and toughness is obtained based on the synergistic effect of nano precipitates and fine-grained (FG) structure. Treatment increases the length per unit area of the effective grain boundary by 37.9%. Compared with the untreated samples, the excellent properties of the steel include increases of 39.2% in impact energy and more than 110 Mpa in ultimate yield strength. The FG structure is produced by the interaction between the MC nano precipitates formed by V alloying and the subgrain structure formed by thermomechanical processing (TMP). Additionally, the anisotropy of the microstructure is eliminated through the innovative introduction of austenitization, resulting in the refinement and homogenization of the grain structure. MC nano precipitates not only prevent the growth of subgrain structure but also enhance the thermal stability of FG structure through a pinning mechanism during austenitization.
收起
摘要 :
The complex interaction between stress concentration and abrasive embedding is a crucial issue in impact-abrasive wear. By comparing with the conventional tempered martensitic steel, this work attempts to find a correlation betwee...
展开
The complex interaction between stress concentration and abrasive embedding is a crucial issue in impact-abrasive wear. By comparing with the conventional tempered martensitic steel, this work attempts to find a correlation between the microstructure and wear resistance of bainitic steel, synergistically strengthened by TiC and the residual austenite (RA). The wear behaviors and work-hardening characteristics of the two steels vary under different impact loads. Bainitic steel has a preferable wear resistance despite its lower initial hardness. This is mainly attributed to the fact that the RA in bainite steel produces a greater work-hardening effect through the transformation-induced plasticity effect and alleviates crack propagation. At the same time, TiC particles resist abrasive embedding into the matrix and effectively decrease the wear failure caused by micro-cutting.
收起
摘要 :
The microstructure design of graphene based reinforcement is an effective route to obtain graphene/aluminum composites with good mechanical properties. In this study, alumina anchored on graphene nanosheets hybrid (Al2O3@GNS) was ...
展开
The microstructure design of graphene based reinforcement is an effective route to obtain graphene/aluminum composites with good mechanical properties. In this study, alumina anchored on graphene nanosheets hybrid (Al2O3@GNS) was in situ synthesized by a sodium chloride template-assisted high-temperature calcination strategy. Al2O3@GNS was used as a reinforcement to fabricate aluminum matrix composites (Al2O3@GNS/Al) by flake powder metallurgy (FPM) route. It was found that Al2O3@GNS was homogenously distributed and a relatively obvious synergistic strengthening effect was acquired by employing Al2O3@GNS as reinforcement of the composites. similar to 1.0vol%-Al2O3@GNS/Al composite obtained the maximum tensile strength of 359MPa, an similar to 131.6% improvement superior to pure Al. The strengthening efficiency of Al2O3@GNS is higher than those reinforced by individual GNS, Al2O3 or its simple mixture. An elongation of 11.2% was achieved in the similar to 1.0vol%-Al2O3@GNS/Al composite, exhibiting a favorable strength-ductility synergy. The synergistic strengthening effect was attributed to the formation of an interlocked network of Al2O3@GNS, which was beneficial to improve the load transfer efficiency from the matrix to reinforcement in the composites.
收起
摘要 :
Here, warm rolling and short-time annealing were performed on plain carbon pseudo-eutectoid steels to obtain multiscale heterostructures with synergistic activation characteristics of multiple strengthening mechanisms. Double the ...
展开
Here, warm rolling and short-time annealing were performed on plain carbon pseudo-eutectoid steels to obtain multiscale heterostructures with synergistic activation characteristics of multiple strengthening mechanisms. Double the yield strength of the material, which also has outstanding ductility. The synergistic effect of the multiscale matrix and the heterogeneous boundaries were revealed.
收起
摘要 :
Cu metal matrix composites (MMCs) incorporated with dual reinforcements of nanocarbons and Al_2O_3 particles with different contents were prepared by accumulative roll-compositing (ARC). Microstructure and properties of the dual-r...
展开
Cu metal matrix composites (MMCs) incorporated with dual reinforcements of nanocarbons and Al_2O_3 particles with different contents were prepared by accumulative roll-compositing (ARC). Microstructure and properties of the dual-reinforced Cu MMCs were systematically investigated and compared with those of the individual-reinforced counterparts. Results showed that both the individual and dual reinforcements can be homoge-nously incorporated into and well-bonded with Cu matrix by ARC. The dual-reinforced Cu MMCs exhibited high strength (up to -747 MPa) and better comprehensive properties of strength/elongation and strength/electrical conductivity than those of the individual counterparts. Moreover, a synergistic strengthening effect of 1 + 1 ＞2 of the dual reinforcements was revealed. The influences of content, distribution and interfacial interaction of the dual reinforcements on the properties of the Cu MMCs were discussed. This study indicated the method and mechanisms for further improving the comprehensive properties of Cu MMCs at high strength level by introducing dual reinforcements.
收起
摘要 :
Here, we report a novel CoCrNiAl_(0.1)Mo_(0.1) medium-entropy alloy, which possessed a complex structure comprising with the non-recrystallized structure, recrystallized structure, fine grains and precipitate phase. The alloy disp...
展开
Here, we report a novel CoCrNiAl_(0.1)Mo_(0.1) medium-entropy alloy, which possessed a complex structure comprising with the non-recrystallized structure, recrystallized structure, fine grains and precipitate phase. The alloy displayed exceptional tensile properties after cold-rolled and annealing at various temperatures in a range of 725-900 ℃. As annealed at 725 ℃, the alloy exhibit a tensile strength of 1304 MPa, and uniform elongation of 22% due to the synergistic strengthening of the high density of dislocation in the non-recrystallized regions, ultrafine grains and precipitates in the recrystallized structure. As annealing increasing, further growth of recrystallization region and grain size, resulting in high ductility but low strength. The alloy achieves excellent strength-ductility combination by adjusting microstructure (degree of recrystallization, sizes of grain and precipitate phase, etc.) at different annealing temperature. These results offer an extremely effective design strategy to enhance strength-ductility trade-off by simple thermal treatment.
收起
原文获取