The effects of rapid heating cyclic heat treatment on mechanical properties of a TiAl based alloy (Ti 33Al 3Cr) were studied by means of an induction heating machine. The results show that: 1) fine fully lamellar micr...The effects of rapid heating cyclic heat treatment on mechanical properties of a TiAl based alloy (Ti 33Al 3Cr) were studied by means of an induction heating machine. The results show that: 1) fine fully lamellar microstructure with colony size of about 50 μm and lamellar spacing of about 0.12 μm can be obtained; 2) the compression mechanical properties can be improved to a large extent and the best comprehensive compression mechanical properties can reach the yield stress 745 MPa, the large flow stress 1 672 MPa and the compression ratio 19.4%; and 3) the compression fracture at room temperature after induction heat treatment and aging is still typical cleavage fracture.展开更多
The effect of incorporating limited-diffusivity elements such as Fe and Ti on thermal stability of the nanocrystalline Al alloy was investigated.Al−10wt.%Fe and Al−10wt.%Fe−5wt.%Ti alloys were fabricated.The initial m...The effect of incorporating limited-diffusivity elements such as Fe and Ti on thermal stability of the nanocrystalline Al alloy was investigated.Al−10wt.%Fe and Al−10wt.%Fe−5wt.%Ti alloys were fabricated.The initial mixtures of powders were milled for 100 h in vacuum.The bulk samples were fabricated from the milled powders in a high frequency induction heat sintering(HFIHS)system.The milled powders and the bulk sintered samples were characterized by X-ray diffraction(XRD),Vickers microhardness,field emission scanning electron microscopy(FESEM-EDS)and transmission electron microscopy(TEM).The observations indicated that Fe and Ti were completely dispersed in the matrix to form a supersaturated solid solution(SSSS)with Al.Additionally,the inclusion of alloying elements led to an increase in hardness and yield strength of the alloy by 127%and 152%,respectively.The elevated temperature compression tests were carried out to evaluate the thermal stability of the alloys.The Al−10wt.%Fe−5wt.%Ti alloy revealed the optimum thermally stable behavior of the three alloys studied.The incorporation of Fe and Ti improved the thermal stability of the developed alloys through inhibiting the grain growth,hindering dissolution and growth of second phases(such as Al13Fe4 and Al13Ti),and forming a stable solid solution.展开更多
This article describes in detail a technique for model!ng cavity optomechanical field sensors. A magnetic or electric field induces a spatially varying stress across the sensor, which then induces a force on mechanica...This article describes in detail a technique for model!ng cavity optomechanical field sensors. A magnetic or electric field induces a spatially varying stress across the sensor, which then induces a force on mechanical eigenmodes of the system. The force on each oscillator can then be determined from an overlap integral between magnetostrictive stress and the corresponding eigenmode, with the optomechanical coupling strength determining the ultimate resolution with which this force can be detected. Furthermore, an optomechanical magnetic field sensor is compared to other magnetic field sensors in terms of sensitivity and potential for miniaturization. It is shown that an optomechanical sensor can potentially outperform state-of-the-art magnetometers of similar size, in particular other sensors based on a magnetostrictive mechanism.展开更多
文摘The effects of rapid heating cyclic heat treatment on mechanical properties of a TiAl based alloy (Ti 33Al 3Cr) were studied by means of an induction heating machine. The results show that: 1) fine fully lamellar microstructure with colony size of about 50 μm and lamellar spacing of about 0.12 μm can be obtained; 2) the compression mechanical properties can be improved to a large extent and the best comprehensive compression mechanical properties can reach the yield stress 745 MPa, the large flow stress 1 672 MPa and the compression ratio 19.4%; and 3) the compression fracture at room temperature after induction heat treatment and aging is still typical cleavage fracture.
文摘The effect of incorporating limited-diffusivity elements such as Fe and Ti on thermal stability of the nanocrystalline Al alloy was investigated.Al−10wt.%Fe and Al−10wt.%Fe−5wt.%Ti alloys were fabricated.The initial mixtures of powders were milled for 100 h in vacuum.The bulk samples were fabricated from the milled powders in a high frequency induction heat sintering(HFIHS)system.The milled powders and the bulk sintered samples were characterized by X-ray diffraction(XRD),Vickers microhardness,field emission scanning electron microscopy(FESEM-EDS)and transmission electron microscopy(TEM).The observations indicated that Fe and Ti were completely dispersed in the matrix to form a supersaturated solid solution(SSSS)with Al.Additionally,the inclusion of alloying elements led to an increase in hardness and yield strength of the alloy by 127%and 152%,respectively.The elevated temperature compression tests were carried out to evaluate the thermal stability of the alloys.The Al−10wt.%Fe−5wt.%Ti alloy revealed the optimum thermally stable behavior of the three alloys studied.The incorporation of Fe and Ti improved the thermal stability of the developed alloys through inhibiting the grain growth,hindering dissolution and growth of second phases(such as Al13Fe4 and Al13Ti),and forming a stable solid solution.
文摘This article describes in detail a technique for model!ng cavity optomechanical field sensors. A magnetic or electric field induces a spatially varying stress across the sensor, which then induces a force on mechanical eigenmodes of the system. The force on each oscillator can then be determined from an overlap integral between magnetostrictive stress and the corresponding eigenmode, with the optomechanical coupling strength determining the ultimate resolution with which this force can be detected. Furthermore, an optomechanical magnetic field sensor is compared to other magnetic field sensors in terms of sensitivity and potential for miniaturization. It is shown that an optomechanical sensor can potentially outperform state-of-the-art magnetometers of similar size, in particular other sensors based on a magnetostrictive mechanism.
