MAGNESIUM ALLOY MAGNESIUM ALLOY MAGNESIUM ALLOY MAGNESIUM ALLOY MAGNESIUM ALLOY MAGNESIUM ALLOY DEVELOPMENT DEVELOPMENT DEVELOPMENT DEVELOPMENT DEVELOPMENT DEVELOPMENT Science within constraints Science within constraints Mihriban Mihriban O. Pekguleryuz O. Pekguleryuz Mihriban O. Pekguleryuz Mihriban O. Pekguleryuz McGill University McGill University McGill University McGill University
Magnesium alloy development challenges the scientist & engineer 360 0 Mg myth myth Cost & availability Knowledge base performance requirements End user constraints Business savvy Industry knowledge lack of knowledge base lack of knowledge base skepticism skepticism Processing requirements WHAT IS REQUIRED ? WHAT IS REQUIRED ?
Mg ALLOY REQUIREMENTS IN AUTOMOTIVE APPLICATIONS Mg ALLOY REQUIREMENTS IN AUTOMOTIVE APPLICATIONS CURRENT USE: INTERIOR CURRENT USE: INTERIOR MID-TO-LONG-TERM MID-TO-LONG-TERM MID-TO-LONG-TERM COMPONENTS COMPONENTS BODY BODY e.g. Instrument Panel, e.g Inner door panel, pillar structures steering wheel - Stiffness, high ductility - Wrought products (formability) - Structural casting alloys (ductility) - Energy absorption Requires new alloys and processes AM alloys AM alloys CHASSIS CHASSIS Wheel, suspension arm e .g. SHORT TERM : POWERTRAIN SHORT TERM : POWERTRAIN - Strength - High ductility, fatigue e.g . Transmission case, engine parts - Corrosion resistance - Creep resistance (150-200C) - Yield strength Requires new alloys - Corrosion resistance - Mg-Al-RE & Mg-Al-Si Requires new alloys
ALLOY TYPES NEEDED IN THE SHORT-TO-MID-TERM CASTING ALLOYS 1990s-o-present - Creep resistant (175 C or above) - Improved castability (thin-walled) New challenges WROUGHT ALLOYS - improved formability, rollability, workability at room temperature - corrosion resistance - low cost processes
DEVELOPMENT OF Mg CREEP RESISTANT CASTING ALLOYS DEVELOPMENT OF Mg CREEP RESISTANT CASTING ALLOYS DEVELOPMENT OF Mg CREEP RESISTANT CASTING ALLOYS DEVELOPMENT OF Mg CREEP RESISTANT CASTING ALLOYS BAC BACKGRO GROUND ND BACKGRO BAC GROUND ND � 1990s: potential use of Mg in the 1990s: potential use of Mg in the powertrain powertrain � North America: oil- -pan, transmission case pan, transmission case North America: oil Europe: engine block and transmission case Europe: engine block and transmission case � Requirements � Requirements : : Creep- -resistance resistance Creep and and tensile yield strength tensile yield strength at and above at and above 150° °C, C, 150 castability castability and others… …. . and others
DEVELOPMENT OF Mg CREEP RESISTANT CASTING ALLOYS DEVELOPMENT OF Mg CREEP RESISTANT CASTING ALLOYS DEVELOPMENT OF Mg CREEP RESISTANT CASTING ALLOYS DEVELOPMENT OF Mg CREEP RESISTANT CASTING ALLOYS BAC BACKGRO BAC BACKGRO GROUND GROUND ND ND � Mg alloys have been traditional considered for die � Mg alloys have been traditional considered for die- -casting casting (HPDC) (HPDC) � Conventional alloys (Mg � Conventional alloys (Mg- -Al, Mg Al, Mg- -Al Al- -Zn) HPDC alloys lose creep resistance above Zn) HPDC alloys lose creep resistance above 120C. 120C. � Traditional creep resistant alloys of Mg (HPDC) perform between � Traditional creep resistant alloys of Mg (HPDC) perform between 120 120- -150C. 150C. � Aerospace alloys (WE42): not die � Aerospace alloys (WE42): not die- -castable castable; expensive ; expensive ALLOY Creep resistance ALLOY Creep resistance TRADITIONAL ALLOYS TRADITIONAL ALLOYS AS41 medium AS21 medium AE42 good up to 150C AEROSPACE ALLOYS AEROSPACE ALLOYS WE42 High (200-250C) T ° T °C C � 1990s to 2003: alloy development activities in North America, E � 1990s to 2003: alloy development activities in North America, Europe, urope, Israel, Australia, China, Japan Israel, Australia, China, Japan
COMMERCIAL AND NEW Mg CREEP RESISTANT ALLOYS (HPDC) COMMERCIAL AND NEW Mg CREEP RESISTANT ALLOYS (HPDC) ALLOY ALLOY DESIGNATION DESIGNATION INVENTOR STATUS / COMMENTS INVENTOR STATUS / COMMENTS Mg- -Al Al- -Si Si AS41 (Mg- -4Al 4Al- -1Si) 1Si) VW Commercial Mg AS41 (Mg VW Commercial AS21 (Mg- -2Al 2Al- -1Si) 1Si) AS21 (Mg Mg- Mg -Al Al- -Si Si (RE) (RE) AS21x AS21x Hydro Mag Hydro Mag. PATENTED . PATENTED Mg- Mg -Al Al- -RE RE AE42 (Mg AE42 (Mg- -4Al 4Al- -2 RE) 2 RE) Dow Dow Commercial Commercial Mg- -Al Al- -Ca Ca AX51 {Mg- -5Al 5Al- -(.2 (.2- -.8)Ca} .8)Ca} ITM WO96/25529 (1995), PD* WO96/25529 (1995), PD* Mg AX51 {Mg ITM Mg- Mg -Al Al- -RE RE- -Ca Ca AEX AEX Nissan- Nissan -UBE UBE EP 0799901 A1 (1997) EP 0799901 A1 (1997) NK** NK** ACM522-- ACM522 --(Mg (Mg- -5Al 5Al- -2RE 2RE- -2Ca) 2Ca) Honda Honda EP 0791 662A1 (NK**) EP 0791 662A1 (NK**) Mg- -RE RE- -Ca ( Ca (Mn Mn) ) EX {Mg- -(2 (2- -5)RE 5)RE- -(0 (0- -1)Ca} 1)Ca} MEL WO96/24701 (NK**) Mg EX {Mg MEL WO96/24701 (NK**) Mg Mg- -Zn Zn- -Al Al- -Ca Ca ZAX850 ZAX850 IMRA IMRA US 5855697 (1999) US 5855697 (1999) Mg- -Al Al- -RE RE- -Ca ( Ca (Sr Sr) ) MRI 153, MRI 230D DSM- -VW US 6139651 (2000) VW US 6139651 (2000) Mg MRI 153, MRI 230D DSM Mg- Mg -Al Al- -Sr Sr AJ {Mg AJ {Mg- -(2 (2- -9)Al 9)Al- -(.5 (.5- -7)Sr} 7)Sr} Noranda Noranda US 6322644 (2001) US 6322644 (2001) Mg- -Al Al- -Ca Ca- -Sr Sr AXJ {Mg- -5Al 5Al- -(2 (2- -3)Ca 3)Ca- -0.07Sr 0.07Sr GM US 6264763 (2001) Mg AXJ {Mg GM US 6264763 (2001) Mg- Mg -Al Al- -Sr Sr- -Ca Ca AJX {Mg AJX {Mg- -(2 (2- -9)Al 9)Al- -(.2 (.2- -.6)Sr .6)Sr- -(.15 (.15- -.3Ca) .3Ca) Noranda Noranda US 6342180 (2002) US 6342180 (2002) * PD: public domain ** NK: status not known
Mg-Al- Mg-Al-Ca Ca Ca ALLOYS BY ITM (INTERMAG)-1995-96 ALLOYS BY ITM (INTERMAG)-1995-96 ALLOYS BY ITM (INTERMAG)-1995-96 Mg-Al- Mg-Al- Ca ALLOYS BY ITM (INTERMAG)-1995-96 Mg-Al-Ca ALLOYS BY ITM (INTERMAG)-1995-96 Mg-Al-Ca ALLOYS BY ITM (INTERMAG)-1995-96 DATE OF DATE OF COMPOSITION (wt%) COMPOSITION (wt%) CLAIMS CLAIMS APPLICATION / APPLICATION / AI AI Zn Zn Mn Mn RE RE Ca Ca Si Si ORIGINATOR ORIGINATOR Alloys with composition to give AI Ca precipitation Alloys with composition to give AI Ca precipitation 2 1996 - ITM Inc 2 1996 - ITM Inc 2 - 6 2 - 6 0.1-0.8 0.1-0.8 good creep resistance (WO96/25529) good creep resistance (WO96/25529) * Source: J.F. King, ‘’Development of Magnesium Diecasting * Source: J.F. King, ‘’Development of Magnesium Diecasting Alloys,’’ Magnesium Alloys and their Applications, B.L. Alloys,’’ Magnesium Alloys and their Applications, B.L. Mordike Mordike, K.U. , K.U. Kainer Kainer, , Eds Eds, , Proc Proc. . Vol Vol. Sponsored by Volkswagen……April 1998, p. 43 . Sponsored by Volkswagen……April 1998, p. 43 CREEP EXTENSION (%) CREEP EXTENSION (%) 150°C, 35 MPA FOR 200 HOURS 150°C, 35 MPA FOR 200 HOURS ALLOYS CREEP EXTENSION (%) AZ91D CREEP EXTENSION (%) AX506 AX508 AX51 AZ91D AE42 0.33 0.26 0.31 0.33 2.54 6 0 2 1 8 5 4 5 0 E X X 5 A A X A A Very good properties but Very good properties but Castability issues issues Castability
Mg Mg- -Al Al Al- -Sr Sr Sr Alloys ( Alloys (Noranda Alloys ( Noranda ) Noranda ) Mg Mg Al Sr Alloys ( Noranda 2- -10% Al, 1.2 10% Al, 1.2- -7%Sr 7%Sr 2 One of the compositions commercialized in automotive engine block One of the compositions commercialized in automotive engine bloc k AJ52x AJ52x AJ62x AJ62x Al 390 alloy insert Al 390 alloy insert α - α -Mg Mg and and Type A Type A Type B Type B Mg J alloy Mg J alloy intermetallics intermetallics BMW hybrid engine block
� The scientific fall out � The scientific fall out The scientific fall out The scientific fall out - Creep involves thermally activated recovery Creep involves thermally activated recovery processes: processes: dislocation motion, dislocation motion, - diffusion) diffusion) - To be prominent above 0.3 T To be prominent above 0.3 T m of Mg and of the solute - m of Mg and of the solute - Mg alloys especially Mg alloys especially diecast diecast alloys have different alloys have different - mechanisms at room to moderate temperatures mechanisms at room to moderate temperatures and moderate stress regimes: and moderate stress regimes: Stress and/or thermally induced precipitation from the Stress and/or thermally induced precipitation from the supersaturated primary phase (e.g. Mg 17 supersaturated primary phase (e.g. Mg 17 Al Al 12 12 ), or through ), or through decomposition of intermetallics intermetallics (in AE alloys) (in AE alloys) decomposition of Creep induced Creep induced which facilitates grain boundary migration which facilitates grain boundary migration Creep induced Creep induced Mg Mg 17 Al 12 Al pptn ppt Mg Mg Al Al 12 ppt pptn 17 17 17 12 12 - Hence we need to prevent this type of Hence we need to prevent this type of pptn pptn - - Use Use metallurgically metallurgically stable precipitates in alloy design stable precipitates in alloy design - - For higher temperatures: more strategies For higher temperatures: more strategies - and alloy phase diagrams need to be and alloy phase diagrams need to be developed. developed. Grain boundary Grain boundary Grain boundary Grain boundary migration migr ation migr migration ation
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