caa a22 4500 463227743 CHVBK 20180405153232.0 cr unu---uuuuu 170326e20071201xx s 000 0 eng 10.1007/s10853-007-2061-4 doi (NATIONALLICENCE)springer-10.1007/s10853-007-2061-4 Formation and retention of local melted films in AZ91 friction stir spot welds [Elektronische Daten] [Peter Su, Adrian Gerlich, Motomichi Yamamoto, Thomas North] The formation of local melted films during friction stir spot welding of as-cast AZ91D and thixomolded AZ91 material is investigated. The average temperatures close to the tip of the rotating pin vary from 438 to 454°C during the dwell period in friction stir spot welding. These measured temperature values are higher than the melting temperature of α-Mg+Mg17Al12 eutectic (437°C). It is suggested that the temperature in the stir zone during the dwell period is determined by the relative proportions of α-Mg and (α-Mg+Mg17Al12) eutectic material, which are incorporated during friction stir spot welding. Based on the stir zone temperature measurements and a detailed examination of material located at the root of the pin thread it is suggested that material is moved downwards via the pin thread and into the stir zone during the dwell period in friction stir spot welding. Evidence of local melted film formation is observed in the stir zone of AZ91 spot welds. It is suggested that melted films are retained since their dissolution rate is much slower in the high temperature stir zone than it is when melted films is formed in the stir zone during Al 7075-T6 friction stir spot welding. The spontaneous melting temperature, solute diffusion rate and the thermodynamic driving force for droplet dissolution are much higher during Al 7075-T6 friction stir spot welding. Springer Science+Business Media, LLC, 2007 Su Peter Department of Materials Science & Engineering, University of Toronto, 184 College St., Room 140, M5S 3E4, Toronto, ON, Canada aut Gerlich Adrian Department of Materials Science & Engineering, University of Toronto, 184 College St., Room 140, M5S 3E4, Toronto, ON, Canada aut Yamamoto Motomichi Department of Materials Science & Engineering, University of Toronto, 184 College St., Room 140, M5S 3E4, Toronto, ON, Canada aut North Thomas Department of Materials Science & Engineering, University of Toronto, 184 College St., Room 140, M5S 3E4, Toronto, ON, Canada aut Journal of Materials Science Springer US; http://www.springer-ny.com 42/24(2007-12-01), 9954-9965 0022-2461 42:24<9954 2007 42 10853 https://doi.org/10.1007/s10853-007-2061-4 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10853-007-2061-4 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Su Peter Department of Materials Science & Engineering, University of Toronto, 184 College St., Room 140, M5S 3E4, Toronto, ON, Canada aut NATIONALLICENCE 700 1- Gerlich Adrian Department of Materials Science & Engineering, University of Toronto, 184 College St., Room 140, M5S 3E4, Toronto, ON, Canada aut NATIONALLICENCE 700 1- Yamamoto Motomichi Department of Materials Science & Engineering, University of Toronto, 184 College St., Room 140, M5S 3E4, Toronto, ON, Canada aut NATIONALLICENCE 700 1- North Thomas Department of Materials Science & Engineering, University of Toronto, 184 College St., Room 140, M5S 3E4, Toronto, ON, Canada aut NATIONALLICENCE 773 0- Journal of Materials Science Springer US; http://www.springer-ny.com 42/24(2007-12-01), 9954-9965 0022-2461 42:24<9954 2007 42 10853 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer