Silicon carbide （SIC） foams with a continuously connected open-cell structure were prepared and characterized for their mechanical performance. The apparent densities of SiC foams were controlled between about 0.4 a...Silicon carbide （SIC） foams with a continuously connected open-cell structure were prepared and characterized for their mechanical performance. The apparent densities of SiC foams were controlled between about 0.4 and 2.3 g/cm^3, with corresponding compressive strengths ranging from about 23 to 60 MPa and flexural strengths from about 8 to 30 MPa. Compressive testing of the SiC foams yielded stress-strain curves with only one linear-elastic region, which is different from those reported on ceramic foams in literature. This can possibly be attributed to the existence of filaments with fine, dense and high strength microstructures. The SiC and the filaments respond homogeneously to applied loading.展开更多
Many shape memory alloys can support large recoverable strains of a few percent by reversible stressinduced martensite transformation,yet they behave non-linear within a narrow operating temperature ra nge.Developing ...Many shape memory alloys can support large recoverable strains of a few percent by reversible stressinduced martensite transformation,yet they behave non-linear within a narrow operating temperature ra nge.Developing the bulk metallic materials with ultra-large linear elasticity over a wide tempe rature range has proven to be difficult.In this work,a material design concept was proposed,that is true elastic deformation and reversible twinning-detwinning deformation run in parallel to overcome this challe nge.By engineering the residual internal stress to realize the concurrency of true elastic deformation and twinning-detwinning deformation,a bulk nanocrystalline NiTi that possesses an ultra-large linear elastic strain up to 5.1 % and a high yield stress of 2.16 GPa over a wide temperature range of 270℃ was developed.This study offers a new avenue for developing the metallic materials with ultra-large linear elasticity over a wide temperature range of 270℃(from 70℃ to-197℃).展开更多
文摘Silicon carbide （SIC） foams with a continuously connected open-cell structure were prepared and characterized for their mechanical performance. The apparent densities of SiC foams were controlled between about 0.4 and 2.3 g/cm^3, with corresponding compressive strengths ranging from about 23 to 60 MPa and flexural strengths from about 8 to 30 MPa. Compressive testing of the SiC foams yielded stress-strain curves with only one linear-elastic region, which is different from those reported on ceramic foams in literature. This can possibly be attributed to the existence of filaments with fine, dense and high strength microstructures. The SiC and the filaments respond homogeneously to applied loading.
基金supported by the National Key R&D Program of China (No. 2018YFB1105100)the National Natural Science Foundation of China (Nos. 51971244 and 51731010)+3 种基金the Science Foundation of China University of Petroleum, Beijing (No. 2462018BJC005)the Pre-research Program of Frontier Science, Ministry of Education (No. 6141A020222)the Research Fund of China Manned Space Engineering (No. 040201)supported by the US Department of Energy, Office of Science, and Office of Basic Energy Science (No. DE-AC02-06CH11357)。
文摘Many shape memory alloys can support large recoverable strains of a few percent by reversible stressinduced martensite transformation,yet they behave non-linear within a narrow operating temperature ra nge.Developing the bulk metallic materials with ultra-large linear elasticity over a wide tempe rature range has proven to be difficult.In this work,a material design concept was proposed,that is true elastic deformation and reversible twinning-detwinning deformation run in parallel to overcome this challe nge.By engineering the residual internal stress to realize the concurrency of true elastic deformation and twinning-detwinning deformation,a bulk nanocrystalline NiTi that possesses an ultra-large linear elastic strain up to 5.1 % and a high yield stress of 2.16 GPa over a wide temperature range of 270℃ was developed.This study offers a new avenue for developing the metallic materials with ultra-large linear elasticity over a wide temperature range of 270℃(from 70℃ to-197℃).
