[1] [1] WU Sh Ch, ZHU Z T. Laser welding and performance evaluation of aluminum alloy ［M］. Beijing: Defense Industry Press, 2014: 13-25(in Chinese).

[2] [2] LI Zh, WANG T, LIU J, et al. Effect of process parameters on corrosion resistance of aluminum alloy hybrid welded joints ［J］. Laser Technology,2019,43(2):189-194（in Chinese）.

[3] [3] DING J K, WANG D P, WANG Y, et al. Effect of post weld heat treatment on properties of variable polarity TIG welded AA2219 aluminum alloy joints ［J］. Transactions of Nonferrous Metals Society of China, 2014, 24(5): 1307-1316.

[4] [4] HE Y, TANG X, ZHU C, et al. Study on insufficient fusion of NG-GMAW for 5083 Al alloy ［J］. The International Journal of Advanced Manufacturing Technology, 2017, 92(9/12): 4303-4313.

[5] [5] SONG X H, JIN X Zh, CHEN Sh Q, et al. Progress of laser-arc hybrid welding and its applications in automotive body manufacture ［J］. Laser Technology, 2015, 39(2): 259-265(in Chinese).

[6] [6] WANG H Y, SUN J, LIU L M. Formation and control mechanism of porosity in 6061-T6 aluminum alloy laser arc hybrid high speed welding ［J］. Chinese Journal of Lasers, 2018, 45(3): 0302001(in Chinese).

[7] [7] XU G X, ZHANG W W, LIU P, et al. Numerical analysis of fluid flow in molten pool of laser GMAW composite heat source welding ［J］. Journal of Metals, 2015, 51(6): 713-723（in Chinese）.

[8] [8] XU Ch Y, LIU Sh Y, ZHANG H, et al. Droplet transfer characteristics and force analysis of laser arc composite welding process ［J］. Journal of Mechanical Engineering, 2018, 54(6): 154-161（in Chinese）.

[9] [9] YANG Y D, LIU J, SHI Y, et al. Effect of nozzle shape on forming quality of aluminum alloy composite welding joint ［J］. Laser Technology, 2018, 42(2): 222-228（in Chinese）.

[10] [10] LIU J, LI Zh, SHI Y, et al. Effect of laser-arc distance on surface flow of laser-GMAW hybrid welding molten pool［J］.Chinese Journal of Lasers, 2018,45(10):1002004(in Chinese).

[11] [11] XIE W, FAN C, YANG C, et al. Effect of acoustic field parameters on arc acoustic binding during ultrasonic wave-assisted arc welding ［J］. Ultrasonics Sonochemistry, 2016, 29: 476-484.

[12] [12] ROSTAMIYAN Y, SEIDANLOO A, SOHRABPOOR H, et al. Experimental studies on ultrasonically assisted friction stir spot welding of AA6061［J］. Archives of Civil & Mechanical Engineering, 2015, 15(2): 335-346.

[13] [13] JIAN X, XU H, MEEK T T, et al. Effect of power ultrasound on solidification of aluminum A356 alloy ［J］. Materials Letters, 2005, 59(2): 190-193.

[14] [14] LIU C, CHEN D, HILL M R, et al. Effects of ultrasonic impact treatment on weld microstructure, hardness, and residual stress ［J］. Materials Science & Technology, 2017, 33(12): 1-9.

[15] [15] XU H, JIAN X, MEEK T T, et al. Degassing of molten aluminum A356 alloy using ultrasonic vibration［J］. Materials Letters, 2004, 58(29): 3669-3673.

[16] [16] LI H X. Study on corrosion resistance of aluminum alloy composite welded Joint by welding process ［D］. Changchun:Changchun University of Science and Technology, 2017: 5-10 （in Chinese）.

[17] [17] LI Y J, WANG J. Principle and application of welding ［M］. Beijing: Chemical Industry Press, 2009: 18-21（in Chinese）.

[18] [18] TUCKER J D, NOLAN T K, MARTIN A J, et al. Effect of travel speed and beam focus on porosity in alloy 690 laser welds ［J］. Journal of Metals, 2012, 64(12): 1409-1417.

[19] [19] GAO M Zh. Study on interface microstructure of ultrasonic assisted brazing joint of AZ31B magnesium alloy/6063 aluminum alloy ［D］. Lanzhou:Lanzhou University of Technology, 2017: 20-25（in Chinese）.

[20] [20] KANG J, ZHANG X, WANG S, et al. The comparison of ultrasonic effects in different metal melts［J］. Ultrasonics, 2015, 57: 11-17.

[21] [21] XU H, JIAN X, MEEK T T, et al. Degassing of molten aluminum A356 alloy using ultrasonic vibration ［J］. Materials Letters, 2004, 58(29): 3669-3673.

[22] [22] MA G, YAN S, WU D, et al. Microstructure evolution and mechanical properties of ultrasonic assisted laser clad yttria stabilized zirconia coating ［J］. Ceramics International, 2017,43(13):9622-9629.

[23] [23] BURKE J E, TURNBULL D. Recrystallization and grain growth ［J］. Progress in Metal Physics, 1952, 3(3): 220-292.

[24] [24] MA L, SHU G, CHEN F. Study on solidification of metal melt in ultrasonic field ［J］. Materials Science and Engineering, 1995(4): 2-7.

[25] [25] GE H L. Study on microstructure change and influence mechanism of aluminum alloy with ultrasonic impact welding ［D］. Harbin :Harbin Institute of Technology, 2016: 32-47 （in Chinese）.