In this work, ultrasonic fatigue behavior of the Ti40Zr10Cu34Pd14Sn2 glassy alloy was investigated at 20 kHz at a stress ratio of R = -1. The number of cycles to failure in the S-N curve obtained in this work did not ...In this work, ultrasonic fatigue behavior of the Ti40Zr10Cu34Pd14Sn2 glassy alloy was investigated at 20 kHz at a stress ratio of R = -1. The number of cycles to failure in the S-N curve obtained in this work did not decrease again even after 107 - 108 cycles unlike previous findings for some steels. The fatigue endurance limit and the fatigue rate were σW = 762 MPa and σW/σB = 0.37, respectively. Fish-eye type inertial crack initiation, reported in many papers on giga-cycle fatigue testing, was not observed. A tendency for the fatigue strength of the Ti40Zr10Cu34Pd14Sn2 glassy alloy specimens to be divided into two groups was observed, that is, specimens with a short fatigue lifetime (6 cycles) with distinct cast defects as crack initiation sites and the other specimens with a long fatigue lifetime (>106 cycles). This may have been caused by accidental nucleation of micro-defects such as impurities, voids and precipitates in the glassy rod specimens during the casting.展开更多
The electrical transport properties of (Ni0.8Nb0.2)100-xZrx (x = 30, 40 and 50) amorphous ribbons and hydrogen charged specimens were investigated. The amorphous ribbons indicated a negative coefficient in the tempera...The electrical transport properties of (Ni0.8Nb0.2)100-xZrx (x = 30, 40 and 50) amorphous ribbons and hydrogen charged specimens were investigated. The amorphous ribbons indicated a negative coefficient in the temperature dependence of their electrical resistivity as well as the typical transport properties of the amorphous alloys with comparatively high values of electrical resistivity, ρ. The normalized temperature coefficient of the resistivity (TCR ≡ 1/ρ300K·dρ/dT) tended to increase with increasing x in the temperature range of 100-300 K. These behaviors would suggest that the transport properties of the present amorphous ribbons were governed by temperature variation of the Debye-Waller factor, not by electron-phonon scattering. The hydrogen charged ribbons obtained by an electrochemical method also showed similar electrical resistivity behaviors as a function of the temperature. However, TCR of x = 40 with hydrogen charged ribbon, in which the amount of absorbed hydrogen was about 14 at%, increased about three times more than that of the pre-charged amorphous ribbon.展开更多
Centimeter-sized Mg65Zn30Ca5 bulk amorphous alloys were fabricated by the spark plasma sintering process from the amorphous powders with a size smaller than 5 la m prepared by ball-milling. The sintered Mg65Zn30Ca5 sa...Centimeter-sized Mg65Zn30Ca5 bulk amorphous alloys were fabricated by the spark plasma sintering process from the amorphous powders with a size smaller than 5 la m prepared by ball-milling. The sintered Mg65Zn30Ca5 samples were in an amorphous state when the spark plasma sintering was performed at a temperature of 383 K under a pressure of 600 MPa. The data of polarization curves presented that the sintered Mg65Zn30Ca5 bulk amorphous alloys exhibited higher corrosion resistance than pure Mg and AZ31B alloy owing to high content of Zn and homogeneous structure. A calcium phosphate compound layer was formed on the sintered Mg65Zn30Ca5 bulk amorphous sample after immersion in Hanks＇ solution, which is effective in improving corrosion resistance and bioactivity. The sintered MgZnCa bulk amorphous alloys with large dimensions broaden the potential application of bulk amorphous alloys in the biomedical fields.展开更多
文摘In this work, ultrasonic fatigue behavior of the Ti40Zr10Cu34Pd14Sn2 glassy alloy was investigated at 20 kHz at a stress ratio of R = -1. The number of cycles to failure in the S-N curve obtained in this work did not decrease again even after 107 - 108 cycles unlike previous findings for some steels. The fatigue endurance limit and the fatigue rate were σW = 762 MPa and σW/σB = 0.37, respectively. Fish-eye type inertial crack initiation, reported in many papers on giga-cycle fatigue testing, was not observed. A tendency for the fatigue strength of the Ti40Zr10Cu34Pd14Sn2 glassy alloy specimens to be divided into two groups was observed, that is, specimens with a short fatigue lifetime (6 cycles) with distinct cast defects as crack initiation sites and the other specimens with a long fatigue lifetime (>106 cycles). This may have been caused by accidental nucleation of micro-defects such as impurities, voids and precipitates in the glassy rod specimens during the casting.
文摘The electrical transport properties of (Ni0.8Nb0.2)100-xZrx (x = 30, 40 and 50) amorphous ribbons and hydrogen charged specimens were investigated. The amorphous ribbons indicated a negative coefficient in the temperature dependence of their electrical resistivity as well as the typical transport properties of the amorphous alloys with comparatively high values of electrical resistivity, ρ. The normalized temperature coefficient of the resistivity (TCR ≡ 1/ρ300K·dρ/dT) tended to increase with increasing x in the temperature range of 100-300 K. These behaviors would suggest that the transport properties of the present amorphous ribbons were governed by temperature variation of the Debye-Waller factor, not by electron-phonon scattering. The hydrogen charged ribbons obtained by an electrochemical method also showed similar electrical resistivity behaviors as a function of the temperature. However, TCR of x = 40 with hydrogen charged ribbon, in which the amount of absorbed hydrogen was about 14 at%, increased about three times more than that of the pre-charged amorphous ribbon.
基金financially supported by the Natural Science Foundation of China under Grant No. 51301091the Natural Science Foundation of Jiangsu Province Grant No. BK20151536+1 种基金the Fundamental Research Funds for the Central Universities No. AE16001the Advanced Materials Development and Integration of Novel Structured Metallic and Inorganic Materials from the Ministry of Education, Sport, Culture, Science and Technology, Japan
文摘Centimeter-sized Mg65Zn30Ca5 bulk amorphous alloys were fabricated by the spark plasma sintering process from the amorphous powders with a size smaller than 5 la m prepared by ball-milling. The sintered Mg65Zn30Ca5 samples were in an amorphous state when the spark plasma sintering was performed at a temperature of 383 K under a pressure of 600 MPa. The data of polarization curves presented that the sintered Mg65Zn30Ca5 bulk amorphous alloys exhibited higher corrosion resistance than pure Mg and AZ31B alloy owing to high content of Zn and homogeneous structure. A calcium phosphate compound layer was formed on the sintered Mg65Zn30Ca5 bulk amorphous sample after immersion in Hanks＇ solution, which is effective in improving corrosion resistance and bioactivity. The sintered MgZnCa bulk amorphous alloys with large dimensions broaden the potential application of bulk amorphous alloys in the biomedical fields.
