High-entropy alloys(HEAs)with face-centered cubic(FCC)phase such as CoCrFeMnNi or CoCrNi generally exhibit ultra-high fracture toughness but relatively low strength.In contrast,body-centered cubic(BCC)HEAs often displ...High-entropy alloys(HEAs)with face-centered cubic(FCC)phase such as CoCrFeMnNi or CoCrNi generally exhibit ultra-high fracture toughness but relatively low strength.In contrast,body-centered cubic(BCC)HEAs often display higher strengths,but the few reports on fracture toughness measurement demonstrate low toughness values.Here we show that the BCC HfNbTaTiZr refractory HEA,which possesses a combination of high strength,good tensile ductility and excellent high-temperature properties,also exhibits a remarkably high fracture toughness.By using the"single specimen"compliance method for J-integral measurement according to the ASTM E1820–17 standard,its fracture toughness K_(JIC)was experimentally determined to be 210 MPa m^(1/2),which renders this HEA among the toughest metallic materials.The excellent damage tolerance makes the HEA promising for applications as high-temperature structural materials such as in aerospace field.展开更多
The strength asymmetry between tension and compression is a typical case of mechanical response of materials.Here we achieve the intrinsic strength asymmetry of six face-centered-cubic perfect crystals（Cu,Au,Ni,Pt,Al...The strength asymmetry between tension and compression is a typical case of mechanical response of materials.Here we achieve the intrinsic strength asymmetry of six face-centered-cubic perfect crystals（Cu,Au,Ni,Pt,Al and Ir）through calculating the ideal tensile and compressive strength with considering the normal stress effect and the competition between different crystallographic planes.The results show that both the intrinsic factors（the ideal shear strength and cleavage strength of low-index planes）and the orientation could affect the strength asymmetry,which may provide insights into understanding the strength of ultra-strong materials.展开更多
It is a long-standing challenge to search for metallic glasses(MGs)with optimal combinations of glassforming ability(GFA),strength and toughness in the vast compositional space.By taking into account both recently dev...It is a long-standing challenge to search for metallic glasses(MGs)with optimal combinations of glassforming ability(GFA),strength and toughness in the vast compositional space.By taking into account both recently developed ellipse criterion and temperature-based GFA criterion,here we established quantitative correlations among compositions,elastic constants,GFA and mechanical properties of MGs,which enable to predict the GFA,fracture strength and fracture surface simultaneously in advance once the compositions of MGs are determined.Experimental data confirm the validity of this approach in prediction.Finally,a strategy for designing MGs with optimal combinations of strength,toughness and GFA is proposed,which allows for high-throughput discovering glass formers with excellent mechanical properties.展开更多
基金financially supported by the National Natural Science Foundation of China(No.51771205)Liao Ning Revitalization Talents Program(No.XLYC1808027)。
文摘High-entropy alloys(HEAs)with face-centered cubic(FCC)phase such as CoCrFeMnNi or CoCrNi generally exhibit ultra-high fracture toughness but relatively low strength.In contrast,body-centered cubic(BCC)HEAs often display higher strengths,but the few reports on fracture toughness measurement demonstrate low toughness values.Here we show that the BCC HfNbTaTiZr refractory HEA,which possesses a combination of high strength,good tensile ductility and excellent high-temperature properties,also exhibits a remarkably high fracture toughness.By using the"single specimen"compliance method for J-integral measurement according to the ASTM E1820–17 standard,its fracture toughness K_(JIC)was experimentally determined to be 210 MPa m^(1/2),which renders this HEA among the toughest metallic materials.The excellent damage tolerance makes the HEA promising for applications as high-temperature structural materials such as in aerospace field.
基金financial support from the National Natural Science Foundation of China under Grant Nos.51331007,51301174 and 51501190
文摘The strength asymmetry between tension and compression is a typical case of mechanical response of materials.Here we achieve the intrinsic strength asymmetry of six face-centered-cubic perfect crystals（Cu,Au,Ni,Pt,Al and Ir）through calculating the ideal tensile and compressive strength with considering the normal stress effect and the competition between different crystallographic planes.The results show that both the intrinsic factors（the ideal shear strength and cleavage strength of low-index planes）and the orientation could affect the strength asymmetry,which may provide insights into understanding the strength of ultra-strong materials.
基金supported by the National Natural Science Foundation of China(NSFC)under Grant Nos.51771205,51331007the Liao Ning Revitalization Talents Program under Grant No.XLYC1808027the Youth Innovation Promotion Association CAS。
文摘It is a long-standing challenge to search for metallic glasses(MGs)with optimal combinations of glassforming ability(GFA),strength and toughness in the vast compositional space.By taking into account both recently developed ellipse criterion and temperature-based GFA criterion,here we established quantitative correlations among compositions,elastic constants,GFA and mechanical properties of MGs,which enable to predict the GFA,fracture strength and fracture surface simultaneously in advance once the compositions of MGs are determined.Experimental data confirm the validity of this approach in prediction.Finally,a strategy for designing MGs with optimal combinations of strength,toughness and GFA is proposed,which allows for high-throughput discovering glass formers with excellent mechanical properties.
