The effects of picosecond Nd:YAG laser irradiation on chemical and morphological surface characteristics of the commercially pure titanium and Ti–13Nb–13Zr alloy in air and argon atmospheres were studied under diffe...The effects of picosecond Nd:YAG laser irradiation on chemical and morphological surface characteristics of the commercially pure titanium and Ti–13Nb–13Zr alloy in air and argon atmospheres were studied under different laser output energy values.During the interaction of laser irradiation with the investigated materials,a part of the energy was absorbed on the target surface,influencing surface modifications.Laser beam interaction with the target surface resulted in various morphological alterations,resulting in crater formation and the presence of microcracks and hydrodynamic structures.Moreover,different chemical changes were induced on the target materials’surfaces,resulting in the titanium oxide formation in the irradiation-affected area and consequently increasing the irradiation energy absorption.Given the high energy absorption at the site of interaction,the dimensions of the surface damaged area increased.Consequently,surface roughness increased.The appearance of surface oxides also led to the increased material hardness in the surface-modified area.Observed chemical and morphological changes were pronounced after laser irradiation of the Ti–13Nb–13Zr alloy surface.展开更多
The oxidation tests of Ti_3AlC_2 were conducted at 1100 and 1200？C in air for 48 and 360 h, respectively,and the effects of high temperature oxidation on the flexural strength and hardness of Ti_3AlC_2 were investiga...The oxidation tests of Ti_3AlC_2 were conducted at 1100 and 1200？C in air for 48 and 360 h, respectively,and the effects of high temperature oxidation on the flexural strength and hardness of Ti_3AlC_2 were investigated. The microstructure, grain size and phase compositions of Ti_3AlC_2 substrate didn＇t change after oxidation, hence the oxide removed Ti_3AlC_2 substrate maintained its initial flexural strength and hardness. However, the flexural strength of oxide retained Ti_3AlC_2 decreased by about 5%. Acoustic emission monitoring indicated that during the process of three-point bending test, the formed Al_2O_3 scale on Ti_3AlC_2 surface fractured firstly in a cleavage manner, then the substrate/oxide interface cracked,and finally the Ti_3AlC_2 substrate fractured. The mechanical degradation was caused by the preferential formation of cracks in brittle Al_2O_3 scale as well as at defective and lacunose grain boundaries of the substrate where stress concentration generated. The mechanical degradation was insensitive to oxidation temperature and time in the present conditions. In addition, the surface hardness increased significantly after oxidation due to the formed hard Al_2O_3 scale on the surface of Ti_3AlC_2 substrate.展开更多
基金This work was financially supported by the Ministry of Education,Science and Technological Development of the Republic of Serbia through Project Nos.ON174004 and ON172019the PhD fellowship of Slađana Laketić.
文摘The effects of picosecond Nd:YAG laser irradiation on chemical and morphological surface characteristics of the commercially pure titanium and Ti–13Nb–13Zr alloy in air and argon atmospheres were studied under different laser output energy values.During the interaction of laser irradiation with the investigated materials,a part of the energy was absorbed on the target surface,influencing surface modifications.Laser beam interaction with the target surface resulted in various morphological alterations,resulting in crater formation and the presence of microcracks and hydrodynamic structures.Moreover,different chemical changes were induced on the target materials’surfaces,resulting in the titanium oxide formation in the irradiation-affected area and consequently increasing the irradiation energy absorption.Given the high energy absorption at the site of interaction,the dimensions of the surface damaged area increased.Consequently,surface roughness increased.The appearance of surface oxides also led to the increased material hardness in the surface-modified area.Observed chemical and morphological changes were pronounced after laser irradiation of the Ti–13Nb–13Zr alloy surface.
基金financial support of the project from the National Natural Science Foundation of China (Nos. 51571205 and 51271191)
文摘The oxidation tests of Ti_3AlC_2 were conducted at 1100 and 1200？C in air for 48 and 360 h, respectively,and the effects of high temperature oxidation on the flexural strength and hardness of Ti_3AlC_2 were investigated. The microstructure, grain size and phase compositions of Ti_3AlC_2 substrate didn＇t change after oxidation, hence the oxide removed Ti_3AlC_2 substrate maintained its initial flexural strength and hardness. However, the flexural strength of oxide retained Ti_3AlC_2 decreased by about 5%. Acoustic emission monitoring indicated that during the process of three-point bending test, the formed Al_2O_3 scale on Ti_3AlC_2 surface fractured firstly in a cleavage manner, then the substrate/oxide interface cracked,and finally the Ti_3AlC_2 substrate fractured. The mechanical degradation was caused by the preferential formation of cracks in brittle Al_2O_3 scale as well as at defective and lacunose grain boundaries of the substrate where stress concentration generated. The mechanical degradation was insensitive to oxidation temperature and time in the present conditions. In addition, the surface hardness increased significantly after oxidation due to the formed hard Al_2O_3 scale on the surface of Ti_3AlC_2 substrate.
