Inconel 718 superalloys deposited by laser solid forming （LSF） were heat treated with solution treatment,intermediate heat treatment （IHT） and two-stage aging treatment in sequence （SITA heat treatment）.The effe...Inconel 718 superalloys deposited by laser solid forming （LSF） were heat treated with solution treatment,intermediate heat treatment （IHT） and two-stage aging treatment in sequence （SITA heat treatment）.The effect of IHT temperature on microstructure,tensile property and notch sensitivity of LSFed Inconel 718 superalloy at 500 ℃ were investigated.As-deposited columnar grains have transformed to equiaxed grains and the grains were refined due to the recrystallization during the SITA heat treatment.It is found that the size and amount of δ phase dispersed at grain boundaries decreased with the increasing of IHT temperature,and δ phase disappeared when the IHT temperature reached 1 020 ℃.The ultimate tensile strength （UTS） and yield strength （YS） of smooth samples increased to a maximum when the IHT temperature reached 980 ℃ and then decreased slightly to a minimum when the IHT temperature was 1 000 ℃,and followed by slight increasing again till the IHT temperature reached 1 020 ℃,resulted from the competition of precipitation strengthening effect of γ″ and γ＇ phase and the grain boundary weakening effect caused by the gradual disappearance of δ phase with increasing the IHT temperature.The notch sensitivity factor （qe） decreased but still greater than 1 as the IHT temperature increased,which is attributed to the decrease of the size and amount of δ precipitation.展开更多
This paper presents the design of a small printed ultra wideband antenna with Band Notched characteristics. Both the free space and on-body performances of this antenna were investigated through simulation. The newly ...This paper presents the design of a small printed ultra wideband antenna with Band Notched characteristics. Both the free space and on-body performances of this antenna were investigated through simulation. The newly designed UWB antenna is more revised small form factor sized, with the ability to avoid interference caused by WLAN (5.15 - 5.825 GHz) and WiMAX (5.25 - 5.85 GHz) systems with a band notch. The return loss response, gain, radiation pattern on free space of the antenna were investigated. After that, the on-body performances were tested on 3-layer human body model with radiation pattern, gain, return loss, and efficiency at 3.5, 5.7, 8, 10 GHz and all the results were compared with free space results. As the on-body performance was very good, the proposed antenna will be suitable to be used for multi-purpose medical applications and sports performance monitoring.展开更多
基金Funded by the Program for New Century Excellent Talents in University of China (No.NCET-06-0879)the National Natural Science Foundation of China (NSFC) (No.50971102)+2 种基金NPU Foundation for Fundamental Research(No.NPU-FFR-JC200808)the Fund of the State Key Laboratory of Solidification Processing (NPU) (Nos.16-TZ-2007 and 39-QZ-2009)supported by the Program of Introducing Talents of Discipline to Universities (No.08040)
文摘Inconel 718 superalloys deposited by laser solid forming （LSF） were heat treated with solution treatment,intermediate heat treatment （IHT） and two-stage aging treatment in sequence （SITA heat treatment）.The effect of IHT temperature on microstructure,tensile property and notch sensitivity of LSFed Inconel 718 superalloy at 500 ℃ were investigated.As-deposited columnar grains have transformed to equiaxed grains and the grains were refined due to the recrystallization during the SITA heat treatment.It is found that the size and amount of δ phase dispersed at grain boundaries decreased with the increasing of IHT temperature,and δ phase disappeared when the IHT temperature reached 1 020 ℃.The ultimate tensile strength （UTS） and yield strength （YS） of smooth samples increased to a maximum when the IHT temperature reached 980 ℃ and then decreased slightly to a minimum when the IHT temperature was 1 000 ℃,and followed by slight increasing again till the IHT temperature reached 1 020 ℃,resulted from the competition of precipitation strengthening effect of γ″ and γ＇ phase and the grain boundary weakening effect caused by the gradual disappearance of δ phase with increasing the IHT temperature.The notch sensitivity factor （qe） decreased but still greater than 1 as the IHT temperature increased,which is attributed to the decrease of the size and amount of δ precipitation.
文摘This paper presents the design of a small printed ultra wideband antenna with Band Notched characteristics. Both the free space and on-body performances of this antenna were investigated through simulation. The newly designed UWB antenna is more revised small form factor sized, with the ability to avoid interference caused by WLAN (5.15 - 5.825 GHz) and WiMAX (5.25 - 5.85 GHz) systems with a band notch. The return loss response, gain, radiation pattern on free space of the antenna were investigated. After that, the on-body performances were tested on 3-layer human body model with radiation pattern, gain, return loss, and efficiency at 3.5, 5.7, 8, 10 GHz and all the results were compared with free space results. As the on-body performance was very good, the proposed antenna will be suitable to be used for multi-purpose medical applications and sports performance monitoring.
