The effect of temperature,T,on the ductility of nanocrystalline(NC)Cu films of different thicknesses on flexible substrates is studied by uniaxial tension.It is found that the NC Cu films will fracture more easily wit...The effect of temperature,T,on the ductility of nanocrystalline(NC)Cu films of different thicknesses on flexible substrates is studied by uniaxial tension.It is found that the NC Cu films will fracture more easily with increasing T,exhibiting the anomalous T effect compared with that of bulk NC metals and freestanding films.Moreover,the T dependence of ductility becomes stronger for thinner films due to the larger decrement of the interfacial strength in thinner films.T-induced softening of the stretchable substrate reduces the interface constraint ability for suppressing strain localization,leading to the anomalous T effect.展开更多
We report the mechanical spectroscopy study of the cold-rolling induced dynamical behavior of crystalline defects in nanocrystalline (NC) nickel The results show that internal friction (IF) peaks in NC nickel can be i...We report the mechanical spectroscopy study of the cold-rolling induced dynamical behavior of crystalline defects in nanocrystalline (NC) nickel The results show that internal friction (IF) peaks in NC nickel can be induced by cold-rolling.An IF peak,originating from dislocation activity,occurs when the strain is in the range of 9.7- 32.8%.Two Bordoni peaks occur when the strain is 39.0% and an IF peak associated with deformation twinning appears when the strain is 42.6%.These results mean that deformation of NC nickel is mediated by different kinds of defects as the strain increases.展开更多
An investigation into the properties of nanocrystalline(NC)materials with sample lengths less than 30 mm seems to be a challenge by using conventional mechanical spectroscopy(MS).We use a newly developed frequency mod...An investigation into the properties of nanocrystalline(NC)materials with sample lengths less than 30 mm seems to be a challenge by using conventional mechanical spectroscopy(MS).We use a newly developed frequency modulation acoustic attenuation mechanical spectroscopy(FMAA-MS)to investigate phase transition in Ni68Fe32 NC alloy(22 nm)where the length of the sample is 10 mm.An internal friction peak accompanied by an abrupt increase in resonant frequency occurs at 641 K,which originates from order-disorder phase transition,confirmed by a vibrating sample magnetometer and differential scanning calorimetry.展开更多
Mechanical spectroscopy measurement is performed to study the internal friction of nanocrystalline （NC） nickel with an average grain size of 23 nm from room temperature to 610 K. An internal friction peak is observe...Mechanical spectroscopy measurement is performed to study the internal friction of nanocrystalline （NC） nickel with an average grain size of 23 nm from room temperature to 610 K. An internal friction peak is observed at about 550 K, which corresponds to the Curie transition process of the NC nickel according to the result of magnetization test. Moreover, the fact that the explained by an analytical model Curie temperature of NC nickel is based on the weakening of cohesive lower than that of coarse-grained nickel is energy.展开更多
基金Supported by the PAPDthe Fundamental Research Funds for the Central Universities+1 种基金the National Natural Science Foundation of Chinathe National Basic Research Program of China.
文摘The effect of temperature,T,on the ductility of nanocrystalline(NC)Cu films of different thicknesses on flexible substrates is studied by uniaxial tension.It is found that the NC Cu films will fracture more easily with increasing T,exhibiting the anomalous T effect compared with that of bulk NC metals and freestanding films.Moreover,the T dependence of ductility becomes stronger for thinner films due to the larger decrement of the interfacial strength in thinner films.T-induced softening of the stretchable substrate reduces the interface constraint ability for suppressing strain localization,leading to the anomalous T effect.
基金Supported by the PAPD(9114021305)the Fundamental Research Funds for the Central Universities of China(1112021302,CDJXS11132225)+1 种基金the National Natural Science Foundation of China(50831004,51001060,11004098,51171078)the National Basic Research Program of China(2010CB631004).
文摘We report the mechanical spectroscopy study of the cold-rolling induced dynamical behavior of crystalline defects in nanocrystalline (NC) nickel The results show that internal friction (IF) peaks in NC nickel can be induced by cold-rolling.An IF peak,originating from dislocation activity,occurs when the strain is in the range of 9.7- 32.8%.Two Bordoni peaks occur when the strain is 39.0% and an IF peak associated with deformation twinning appears when the strain is 42.6%.These results mean that deformation of NC nickel is mediated by different kinds of defects as the strain increases.
基金by the National Basic Research Program of China under Grant No 2010CB631004the Fundamental Research Funds for the Central Universities(1112021302,1106021343 and 1116021301)the PAPD,and the National Natural Science Foundation of China(11004098,50831004,51001060).
文摘An investigation into the properties of nanocrystalline(NC)materials with sample lengths less than 30 mm seems to be a challenge by using conventional mechanical spectroscopy(MS).We use a newly developed frequency modulation acoustic attenuation mechanical spectroscopy(FMAA-MS)to investigate phase transition in Ni68Fe32 NC alloy(22 nm)where the length of the sample is 10 mm.An internal friction peak accompanied by an abrupt increase in resonant frequency occurs at 641 K,which originates from order-disorder phase transition,confirmed by a vibrating sample magnetometer and differential scanning calorimetry.
基金Supported by the National Basic Research Programme of China under Grant No 2004CB619305, and the National Natural Science Foundation of China under Grant Nos 50461001, 50571044 and 50831004.
文摘Mechanical spectroscopy measurement is performed to study the internal friction of nanocrystalline （NC） nickel with an average grain size of 23 nm from room temperature to 610 K. An internal friction peak is observed at about 550 K, which corresponds to the Curie transition process of the NC nickel according to the result of magnetization test. Moreover, the fact that the explained by an analytical model Curie temperature of NC nickel is based on the weakening of cohesive lower than that of coarse-grained nickel is energy.
