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使用Nd~(3+):YAG脉冲激光器产生的脉冲能量为12.5 J,频率10 Hz,波长1064 nm的脉冲激光研究了强激光冲击下的Ti-6Al-4V合金表面响应,用SEM和TEM及IFFT方法分析了激光冲击强化造成的微结构响应.结果表明,激光冲击可使Ti -6Al- 4V合金表面硬度增加80%以上,残余压应力达到500 MPa以上.在激光冲击产生的超高能量和超高应变率作用下,具有α/β两相结构的Ti-6Al-4V合金的激光冲击强化效应表现出明显的择优倾向.在较低冲击能量下,β相优先获得形变强化;在较高的冲击能量下,α和β相才能同时获得相当的形变强化,且优先强化相出现过饱和强化现象.位错增殖是冲击强化的主要微观机制,增殖形式多为定向发射和位错偶极子,α和β相则以半共格方式协调形变;在冲击强化区域内呈现应变屏蔽现象,其源于形变缺陷的自组织,是材料在激光冲击形变时的微观约束条件和激光冲击单点累积形变方式以及α/β两相的相间强度与结构差异共同作用所致.
The surface response of Ti-6Al-4V alloy under intense laser shock was studied by pulsed laser with pulse energy of 12.5 J, frequency of 10 Hz and wavelength of 1064 nm, which was produced by Nd ~ (3 +): YAG pulsed laser. IFFT method was used to analyze the microstructural response caused by laser shock. The results show that the laser shock can increase the surface hardness of Ti-6Al-4V alloy by more than 80% and the residual compressive stress of 500 MPa. Under the condition of high strain rate, the laser shock strengthening effect of Ti-6Al-4V alloy with α / β two-phase structure shows obvious preferential tendency. At lower impact energy, The impact strength of the α and β phase can be obtained at the same time the corresponding deformation strengthening, and the preferential strengthening phase appears supersaturation strengthening phenomenon Dislocation proliferation is the main micro-mechanism of impact strengthening, the proliferation of mostly multi-directional emission and dislocation dipoles , and the α and β phases coordinate and deform in a semi-coherent manner. Strain shielding phenomenon appears in the area of impact strengthening, which is derived from the self-organization of deformation defects. It is the microscopic constraint condition and the single point accumulation of laser shock when the material is deformed by laser shock shape Variable mode and α / β two-phase interphase strength and structural differences caused by the interaction.