通过激光熔覆沉积技术制备应用于航空航天工业的Nb Mo Ta Ti难熔高熵合金材料,通过X射线衍射判断出成形的合金晶体结构为体心立方的单相固溶体结构。高熵合金晶粒尺寸大多在2~12μm之间;平均显微硬度为397.6HV,室温抗压强度为1301.83MPa...通过激光熔覆沉积技术制备应用于航空航天工业的Nb Mo Ta Ti难熔高熵合金材料,通过X射线衍射判断出成形的合金晶体结构为体心立方的单相固溶体结构。高熵合金晶粒尺寸大多在2~12μm之间;平均显微硬度为397.6HV,室温抗压强度为1301.83MPa,1000℃高温抗压强度只达到347.28MPa,其原因可能与激光熔覆沉积成形Nb Mo Ta Ti高熵合金的过程中产生的气孔、未熔化/不完全熔化的Ta粉末粒子和裂纹有关,需进一步研究。展开更多
The microstructure of Mg-8Zn-1Y alloy solidified under super-high pressure was analyzed through X-ray diffraction（XRD）, scanning electron microscopy（SEM） and energy dispersive spectroscopy（EDS）. And, compression...The microstructure of Mg-8Zn-1Y alloy solidified under super-high pressure was analyzed through X-ray diffraction（XRD）, scanning electron microscopy（SEM） and energy dispersive spectroscopy（EDS）. And, compression deformation behavior at room-temperature was studied. The results showed that the microstructure of Mg-8Zn-1Y alloy solidified under ambient pressure and super-high pressure was both mainly composed of ■-Mg and quasicrystal I-Mg3Zn6 Y. Solidification under super-high pressure contributed to refining solidified microstructure and changing morphology of the intergranular second phase. The morphology of intergranular second phase（quasicrystal I-Mg3Zn6Y） was transformed from continuous network（ambient pressure） to long island（high pressure） and finally to granular（super-high pressure） with the increase in pressure. The compressive strength, yield strength and rupture strain of the samples solidified under ambient pressure were significantly improved from 262.6 MPa, 244.4 MPa and 13.3% to 437.3 MPa, 368.9 MPa and 24.7% under the pressure of 6 GPa, respectively. Under ambient pressure, cleavage plane on compressive fracture was large and smooth. When it was solidified under the pressure ranging from 4 to 6 GPa, cleavage plane on compressive fracture was small and coarse. In addition, dimple, tear ridge and lobate patterns existed.展开更多
TiC-TiB2/Cu composites were prepared by self-propagating high-temperature synthesis with pseudo hot isostatic pressing using Ti, B4C, and Cu powders. The compressive deformation of the composites at high tem- perature...TiC-TiB2/Cu composites were prepared by self-propagating high-temperature synthesis with pseudo hot isostatic pressing using Ti, B4C, and Cu powders. The compressive deformation of the composites at high tem- perature was investigated. It is found that the maximum compressive strength decreases with the increase of tem- perature and Cu content. The deformation of the composites includes the steps of elastic, stable theology, and inaction. The maximum strain is in the range of 5 %-10 %. Before fracture, TiC-TiB2/40Cu becomes drum-shaped at 1123 K; however, TiC-TiB2/20Cu only has a brittle frac- ture along the axial direction of 45~. The results show that the compressive strength of TiC-TiB2/Cu decreases from 823 to 1223 K. However, the maximum compressive strength of TiC-TiB2/20Cu reaches 1850 MPa at 823 K, which predicts that this series of composites could be applied to high-temperature compressive materials.展开更多
文摘通过激光熔覆沉积技术制备应用于航空航天工业的Nb Mo Ta Ti难熔高熵合金材料,通过X射线衍射判断出成形的合金晶体结构为体心立方的单相固溶体结构。高熵合金晶粒尺寸大多在2~12μm之间;平均显微硬度为397.6HV,室温抗压强度为1301.83MPa,1000℃高温抗压强度只达到347.28MPa,其原因可能与激光熔覆沉积成形Nb Mo Ta Ti高熵合金的过程中产生的气孔、未熔化/不完全熔化的Ta粉末粒子和裂纹有关,需进一步研究。
基金Project supported by National Natural Science Foundation of China(51475486)Natural Science Foundation of Hebei Province(E2013501096)
文摘The microstructure of Mg-8Zn-1Y alloy solidified under super-high pressure was analyzed through X-ray diffraction（XRD）, scanning electron microscopy（SEM） and energy dispersive spectroscopy（EDS）. And, compression deformation behavior at room-temperature was studied. The results showed that the microstructure of Mg-8Zn-1Y alloy solidified under ambient pressure and super-high pressure was both mainly composed of ■-Mg and quasicrystal I-Mg3Zn6 Y. Solidification under super-high pressure contributed to refining solidified microstructure and changing morphology of the intergranular second phase. The morphology of intergranular second phase（quasicrystal I-Mg3Zn6Y） was transformed from continuous network（ambient pressure） to long island（high pressure） and finally to granular（super-high pressure） with the increase in pressure. The compressive strength, yield strength and rupture strain of the samples solidified under ambient pressure were significantly improved from 262.6 MPa, 244.4 MPa and 13.3% to 437.3 MPa, 368.9 MPa and 24.7% under the pressure of 6 GPa, respectively. Under ambient pressure, cleavage plane on compressive fracture was large and smooth. When it was solidified under the pressure ranging from 4 to 6 GPa, cleavage plane on compressive fracture was small and coarse. In addition, dimple, tear ridge and lobate patterns existed.
基金financially supported by the National Natural Science Foundation of China(No.51172057)the Science Innovate Talents Special Foundation of Harbin(No.2011RXXG011)
文摘TiC-TiB2/Cu composites were prepared by self-propagating high-temperature synthesis with pseudo hot isostatic pressing using Ti, B4C, and Cu powders. The compressive deformation of the composites at high tem- perature was investigated. It is found that the maximum compressive strength decreases with the increase of tem- perature and Cu content. The deformation of the composites includes the steps of elastic, stable theology, and inaction. The maximum strain is in the range of 5 %-10 %. Before fracture, TiC-TiB2/40Cu becomes drum-shaped at 1123 K; however, TiC-TiB2/20Cu only has a brittle frac- ture along the axial direction of 45~. The results show that the compressive strength of TiC-TiB2/Cu decreases from 823 to 1223 K. However, the maximum compressive strength of TiC-TiB2/20Cu reaches 1850 MPa at 823 K, which predicts that this series of composites could be applied to high-temperature compressive materials.
