An Investigation on the Copper Rich Phases in Al Alloys

Transcription

1 71 An Investigation on the Copper Rich Phases in Al Alloys A. V. Golpayegani - M. Divandari Iran University of Science and Technology. ( In Situ Alloying ) ( EDS ).. AlCu () Al 2 Cu () Si. (CuFeMn) 3 Si 2 Al 15 Al 5 CuFeSi -Al 5 FeSi ABSTRACT Al-Cu alloys are one of the most frequent aluminium alloys used in aerospace industry. In this research in-situ alloying was used to produce and investigate some of Cu-rich phases which may form in a broad range of Al-Cu alloys. Energy dispersive x-ray and SEM technique was used to study different phases which may form in this family of alloys. Cu rich alloys like AlCu, Al2Cu and other Si and Fe content intermetallics were considered in the Al-Cu wire interface.

2 81 %/ %.. bct Al 2 Cu () Al 2 Cu (). % AlCu () AlCu (). % % %.. AlCu 4 () %. % ().[] Al-Si-Cu-Fe. Al 5 CuFeSi -Al 5 FeSi.[] Al 5 CuFeSi. (CuFeMn) 3 Si 2 Al 15.[]. -Al 5 FeSi.[] (). / g/cm 3 %..[] ( % % )...[] ( ).( ) AlCu 3 Al 2 Cu 3.[]. Table 1- Intermetallics which may form in Al-Cu alloys and their composition. (wt% Cu) (wt% Cu) (Al) (Cu)

3 91 / / / / cm.( ). Fig 2- Schematic view showing the complete polystyrene pattern.. Fig 3- Schematic view showing the position of Cu wire inside the polystyrene pattern.. Table 2- Chemical composition of 356 Al alloy used in this work. Al Si Cr Cu / Fe / Sr / Mg / Ti / Mn / Other / / Ni /. CO 2. CO 2.. () D55 HANYOUNG. C.. µm ( ). () E300 Olympus CARL ZEISS ( SEM ). Cam Scan MV2300 TE. BUHLER MICROMET

4 02 () () / ( SEM ) CuAl 2. / mm -Al/CuAl 2 (CuFeMn) 3 Si 2 Al 15 -Al 5 FeSi. -Al 5 FeSi () () () () () () (). ). ( Table 3- Etchant and conditions they were used in this work. NaOH H 3 PO 4 HNO 3 C C -Al/CuAl 2 Al 2 Cu () () (). ( SEM )./ mm %..NaOH Fig 6- SEM microstructure of the specimen with a 0.8 mm diameter size Cu wire. Note the microstructure of the interface showing different types of phases which may form in an Al-Cu diagram. NaOH etched..() Table 4- Chemical analysis (atomic%) of the phase shown in figure 6. ( ) ( Atomic% ) -Al 5 FeSi Si K Fe K / / / %./ mm.h 3 PO 4 Fig 4- Optical microstructure of the specimen having a 0.6 mm diameter size Cu wire. H 3 PO 4 etched %./ mm.hno 3 Fig 5- Optical microstructure of the specimen having a 0.8 mm diameter size Cu wire. Note the shape and the morphology of the phase in the interface. HNO 3 etched

5 12 ( SEM)./ mm.naoh %. Fig 8-SEM microstructure of the specimen with a 1.2 mm diameter size Cu wire. Two phases have been form similar to a ring around the Cu wire. NaOH etched..() Table 6- Chemical analysis (atomic%) of the phase shown in figure 8. () (Atomic%) () / Cu K / () / Cu K / AlCu (2) / Al Si K / 2 Cu () Cu K / ().. Table 7- Microhradness of phases shown in the figure 8. ( HV ) / / / / ( SEM ) %./ mm.naoh. Fig 7- SEM microstructure of the specimen with a 1.2 mm diameter size Cu wire. Note the microstructure of different types of phases which may form in an Al-Cu and also a ring which has been formed around the Cu wire. NaOH etched..() Table 5- Chemical analysis (atomic%) of the phase shown in figure 7. ( ) ( Atomic% ) () () () Cu K Si K Cu K Si K Mn K Fe K Cu K / / / / / / / / / / ().. ()

6 22. Fig 9- Schematic diagram of the ring shape phases that have been formed at the interface of Cu wire and Al alloy.. ( ).. :.. (). (CuFeMn) 3 Si 2 Al 15. () -Al 5 FeSi. (). () -Al 5 FeSi. () -Al 5 FeSi (CuFeMn) 3 Si 2 Al 15 () () Al 2 Cu (). -Al/CuAl 2. ( ) H 3 PO 4 HNO 3 ( - ). ( - ) () (). -Al/CuAl 2 () ( EDS ) () (). Al 2 Cu () () (). ( ) ( ) Al 2 Cu () ( ). ( ) () ( EDS ). ( 2 ). AlCu ().... ().

7 32.. Al 2 Cu () AlCu ( 2 ) :. - Si (CuFeMn) 3 Si 2 Al 15 Al 5 CuFeSi Al 5 FeSi. -Al 5 FeSi... L. Backerud et ) C. Triveno Rios et al., ) ( al., 1990 Y. ) ( B. Closet et al., 1982) ( ( L. Liu et al., Al 5 FeSi (CuFeMn) 3 Si 2 Al 15 Table 8- A comparison between the reported analysis (atomic%) of the phases shown in the table. Al Si Fe Cu Mn / / / / / Backerud (CuFeMn) / / / / / 3 Backerud Si 2 Al 15 / / / / / Rios /// / / - Al 5 FeSi / / / / / / / / / /// Closet Liu Rios " ". 2- Federico M. Mazzolani, " Aluminum Alloy Structures ", Second Edition, E & FN Spon, London, L. F. Mondolfo, " Aluminum Alloys: Structure and Properties ", Butterworths, Boston, L. Lasa, J. M. Rodriguez-Ibabe, " Characterization of the Dissolution of the Al 2 Cu Phase in Two Al Si Cu Mg Casting Alloys Using Calorimetry ", Materials Characterization, 48 (2002), pp ASM Metals Handbook, Vol. 3, " Alloy Phase Diagram ", Robert E. Reed Hill, Reza Abbaschian, " Physical Metallurgy Principles ", 3rd Edition, PWS Publishing Co., Boston, T. J. Bastow, S. Celotto, " Structure Evolution in Dilute Al(Cu) Alloys Observed by 63Cu NMR ", Acta Materialia 51 (2003), pp ) ( ) "... ". 9- C. Triveno Rios, R. Caram, C. Bolfarini, W.J. Botta F. and C.S. Kiminami, "Intermetallic Compounds in The Al-Si-Cu System ", Acta Microscopica, Volume 12, Number 1, December Z. Li, A.M. Samuel, F.H. Samuel, C. Ravindran, S. Valtierra, H.W. Doty, " Parameters Controlling the Performance of AA319-type Alloys Part I. Tensile properties ", Materials Science and Engineering A 367 (2004), pp