Microstructural evolution and phase transformation of hydrogenated and dehydrogenated TC21 alloys were investigated by optical microscopy （OM）, X-ray diffraction （XRD） and transmission electron microscopy （TEM）....Microstructural evolution and phase transformation of hydrogenated and dehydrogenated TC21 alloys were investigated by optical microscopy （OM）, X-ray diffraction （XRD） and transmission electron microscopy （TEM）. XRD peaks ofαandβphases after hydrogenation shifted to low angle because of lattice expansion with the solution of hydrogen atoms. Microstructure of TC21 alloy after hydrogenation changed apparently. Compared to the as-received one, the contrasts of equiaxedαphase and transformedβphase under optical microscope were reversed. In addition, XRD and TEM analyses revealed that hydrides and α′ martensite precipitated fromαandβphases. Bulk of twins and some Ti3Al particles were observed in hydrogenated TC21 alloy, which means that hydrogen led to the redistribution of alloying elements inαandβphase. After dehydrogenation, the microstructure of TC21 alloy was similar to that of the as-received one, which consisted ofαandβphases.展开更多
A novel technique for fabricating TiB_2/Al composites in molten aluminum was introduced. The formation mechanism of brittleAl,Ti particulates up to 30 m in size produced in the composites was studied and a method of e...A novel technique for fabricating TiB_2/Al composites in molten aluminum was introduced. The formation mechanism of brittleAl,Ti particulates up to 30 m in size produced in the composites was studied and a method of eliminating them was proposed. The resultsshow that (l) the brittle Al,Ti particulates are always present in the composites when the molar ratio of Ti to B 'T,:nB is l:2; and (2) theformation of the brittle Al,Ti phase can be avoided entirely from the final product by using a proper 'T,:nB of l:4 in the Ti-B-Al preforms.In the former case, the tensile elongation of the composite is only 4%, much lower than the value of pure aluminum (20%). In the latercase, the tensile elongation of this composite is 10%, higher than the value of the composite with a lot ofAl,Ti (4%), whereas the ultimatetensile stfength of the former is nearly that of the later.展开更多
基金Project(Z1120117)supported by the Key Program in Xihua University,ChinaProject(12201453)supported by Department of Education Research Fund in Sichuan Province
文摘Microstructural evolution and phase transformation of hydrogenated and dehydrogenated TC21 alloys were investigated by optical microscopy （OM）, X-ray diffraction （XRD） and transmission electron microscopy （TEM）. XRD peaks ofαandβphases after hydrogenation shifted to low angle because of lattice expansion with the solution of hydrogen atoms. Microstructure of TC21 alloy after hydrogenation changed apparently. Compared to the as-received one, the contrasts of equiaxedαphase and transformedβphase under optical microscope were reversed. In addition, XRD and TEM analyses revealed that hydrides and α′ martensite precipitated fromαandβphases. Bulk of twins and some Ti3Al particles were observed in hydrogenated TC21 alloy, which means that hydrogen led to the redistribution of alloying elements inαandβphase. After dehydrogenation, the microstructure of TC21 alloy was similar to that of the as-received one, which consisted ofαandβphases.
文摘A novel technique for fabricating TiB_2/Al composites in molten aluminum was introduced. The formation mechanism of brittleAl,Ti particulates up to 30 m in size produced in the composites was studied and a method of eliminating them was proposed. The resultsshow that (l) the brittle Al,Ti particulates are always present in the composites when the molar ratio of Ti to B 'T,:nB is l:2; and (2) theformation of the brittle Al,Ti phase can be avoided entirely from the final product by using a proper 'T,:nB of l:4 in the Ti-B-Al preforms.In the former case, the tensile elongation of the composite is only 4%, much lower than the value of pure aluminum (20%). In the latercase, the tensile elongation of this composite is 10%, higher than the value of the composite with a lot ofAl,Ti (4%), whereas the ultimatetensile stfength of the former is nearly that of the later.
