Constitutional Properties of Selected Ternary R-Ni-Al alloys (R= Ce, Sm)

Transcription

1 University of Genoa, Department of Chemistry and Industrial Chemistry, INSTM, UdR Genova Constitutional Properties of Selected Ternary R-Ni-Al alloys (R= Ce, Sm) S. Delsante, G. Borzone

2 The addition of misch metal to aluminium-based alloys improves: Tensile strength Heat resistance Vibration resistance Corrosion resistance Extrudability Low-density glassy alloys contain: ~ 90 at% Al, 5 to 9 at% transition metals (Fe, Co, Ni, Rh) ~ 5 at% rare earths (Ce, Nd, Y) Amorphous phases formed in the La-Ni-Al system (Inoue 1997) They have: High tensile strength Crystallization temperature between250 C and 300 C Nanocrystal dispersions of essentially pure Al Low density (aerospace industry) (ASM Gschenidner vol.2, 1990)

3 Phase relations of the Sm Ni Al ternary system at 500 C in the at.% Al region S. Delsante, R. Raggio and G. Borzone - Intermetallics, 16 (11-12), 2008, A Revision of the Al-Rich Region of the Sm-Al Phase Diagram: The Sm 3 Al 11 Phase S. Delsante, R. Raggio, G. Borzone and R. Ferro -Journal of Phase Equilibria and Diffusion, 28 (3), 2007, The Al-rich region in the Y Ni Al system: microstructures and phase equilibria R. Raggio, G. Borzone and R. Ferro -Intermetallics, 8 (3), 2000, Thermodynamic analysis and assessment of the Ce Ni system M. Palumbo, G. Borzone, S. Delsante, N. Parodi, G. Cacciamani, R. Ferro, L. Battezzati, M. Baricco - Intermetallics, 12 (12), 2004, Chemical and thermodynamic properties of several Al Ni R systems G. Borzone, R. Raggio, S. Delsante and R. Ferro -Intermetallics, 11 (11-12), 2003, Thermodynamic investigation of samarium nickel alloys G. Borzone, N. Parodi, R. Raggio and R. Ferro -Journal of Alloys and Compounds, , 2001, Synthesis and Structural Characterization of Ternary Compounds Belonging to the Series RE 2+m Ni 4+m Al 15+4m (RE rare earth metal) S. Delsante, K. W. Richter, H. Ipser and G. Borzone - Z. Anorg. Allg. Chem., 635, 2009, Influence of rare earth metals on the characteristics of anodic oxide films on aluminium and their dissolution behaviour in NaOH solution F. Rosalbino, S. Delsante, G. Borzone and E. Angelinii - Corrosion Science, 52 (2), 2010, Hydrogen evolution reaction on Ni-RE (RE=rare earth) next term crystalline alloys F. Rosalbino, G. Borzone, E. Angelinia and R. Raggio - Electrochimica Acta, 48 (25-26), 2003,

4 The aim of this work is the investigation of the isothermal sections at 800 C of the R-Ni-Al systems (R= Ce and Sm) in the Al-rich part to underline similarities and differences in the formation of ternary phases and in the established phase relationships Why Ce and Sm? Ce represents the light rare earth, Sm is known to have a boundary behavior between light and heavy rare earths Outline Literature data on R-Ni-Al systems(r = Ce and Sm) Experimental details Results and discussion

5 Three recent publications about the Ce-Ni-Al system: 1. [08Tang]: Experimental investigation (Intermetallics 16, 2008, ) of the Al-Ce-Ni system at 800 C 2. [09Tang]: The phase equilibria of the Al-Ce-Ni system at 500 C (JALCOM 470, 2009, ) 3. [10Tang]: Correlation between thermodynamics and glass forming ability in the Al-Ce-Ni system (Intermetallics 18, 2010, )

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7 After a thermodynamic modeling 10 invariant reactions in the Al-rich corner have been computedby[10tang]. TheyconfirmedsomeofthembyDTA experiments. -E1: L Al + Ce 3 Al 11 + NiAl 3 (628.2 C) -U1: L + Ce 4 Ni 6 Al 23 Ce 3 Al 11 + NiAl 3 (735.7 C) -U2: L + Ni 2 Al 3 Ce 4 Ni 6 Al 23 + NiAl 3 (843.0 C) -U3: L + CeNiAl 4 Ce 4 Ni 6 Al 23 + Ce 3 Al 11 (896.5 C) -U4: L + CeNi 2 Al 5 Ce 4 Ni 6 6Al 23 + Ni 2 Al 3 (901.1 C) -P1: L+ CeNiAl 4 + CeNi 2 Al 5 Ce 4 Ni 6 Al 23 (998.2 C) -U5: L + CeAl 4 L + Ce 3 Al 1 11( C) -U6: L + βceal 3 CeNiAl 4 4+ CeAl 4 ( C) -U7: L+ CeAl 2 βceal 3 + CeNiAl 4 ( C) -P2: L + CeAl 4 + CeAl 2 βceal 3 ( C)

8 Binary and ternary phases in the Al-rich part for the relevant phase diagrams Phase Composition / at..% Pearson symbol - type structure Ce Ni Al Ce 3 Al oi28-la 3 Al 11 α-ceal hp8-ni 3 Sn CeAl cf24-cu 2 Mg Al 3 Ni cp4-cu 3 Au Al 3 Ni hp5-al 3 Ni 2 Ce 4 Ni 6 Al ms66-y 4 Ni 6 Al 23 CeNiAl oc24-ynial 4 CeNi 2 Al oi16-prni 2 Al 5 Ce 12.1 Ni 28.1 Al Unknown (reported only at 800 C) In [99Belov] the existence of a ternary eutectic reaction (L Al + NiAl 3 +CeAl 4 *)withaglobalcompositionce 2.6 Ni 2.6 Al 94.8 andat E = 627 C has been reported

9 Two recent publications about the Sm-Ni-Al system: 1. [08Delsante]: Phase relations of the Sm Ni Al ternary system at 500 C in the at.% Al region; (Intermetallics, 16 (11-12), 2008, ) 2.[09Delsante]: Synthesis and Structural Characterization of Ternary Compounds Belonging to the Series RE 2+m Ni 4+m Al 15+4m (RE rare earth metal); (Z. Anorg. Allg. Chem., 635, 2009, )

10 Isothermal section at 500 C 1Sm 4 Ni 6 Al 23 2SmNiAl 4 3SmNiAl 3 4SmNi 2 Al 3 5SmNiAl 2 6SmNiAl E 1 : L Al + Sm 3 Al 11 +Sm 4 Ni 6 Al 23 (Sm 2.5 Ni 2.5 Al 95 ) E 2 : L Al + NiAl 3 +Sm 4 Ni 6 Al 23 (Sm 1 Ni 2 Al 97 )

11 Binary and ternary phases in the Al-rich part for the relevant phase diagrams Phase / T range ( C) Composition / at.% Pearson symbol - type structure Sm Ni Al SmAl op16-eral SmAl hp8-ni 3 Sn SmAl cf24-cu 2 Mg AlNi cp2-cscl Al 3 Ni cp4-cu 3 Au Al 3 Ni hp5-al 3 Ni 2 Sm 3 Ni 5 Al os108-gd 3 Ni 5 Al 19 (stable only at 800 C) Sm 4 Ni 6 Al ms66-y 4 Ni 6 Al 23 SmNiAl oc24-ynial 4 SmNiAl op20-ynial 3 SmNiAl os16-cumgal 2 SmNi 2 Al hp18-honi2.6ga2.4

12 Experimental techniques Pieces of the elements in pure Ar atmosphere Synthesis in alumina crucibles by induction melting Annealing for days at 800 C Quenching in ice-water ISOTHERMAL SECTION INVESTIGATIONS CHARACTERIZATION OF THE ALLOYS LOM SEM EPMA XRD Differential Scanning Calorimetry and Thermal Analysis were also performed on some Ce-Ni-Al alloys

13 Ce-Ni-Al system: 11 alloys in the composition range at.% Al have been synthesized and completely characterized Sm-Ni-Al system: 19 alloys in the composition range at.% Al have been synthesized and completely characterized

14 Results

15 Ce-Ni-Al: isothermal section at 800 C Grey phase: NiAl 3 White phase: Ce 3 Al 11 liquidus (ternary eutectic morphology) 1.Ce 4 Ni 6 Al 23 2.CeNiAl 4 Composition and crystal structures of the ternary phases Ce 4 Ni 6 Al 23 (ms66- Y 4 Ni 6 Al 23, CeNiAl 4 (os24-ynial 4 ) weree confirmed For the Ce 3 Al 11 a Ni solubility of ~2 at.% was observed. The previously established phase relationships have been confirmed

16 BSE micrograph of a Ce 2.5 Ni 3.0 Al 94.5 sample: ternary eutectic morphology As cast Annealed at 500 C After DSC analysis, 1 C/min The microstructure of the ternary eutectic is greatly affected by the solidification T E = 622 C measured by DSC

17 DTA performed Vienna by Dr. K. Richter 2 nd cycle 1 st cycle The experimental results by DTA analysis confirmed the calculated temperatures for the invariant reactions reported by [10Tang], with a good agreement for U 3 and P 1 Ce 4 Ni 6 Al 23 U 1 : L + Ce 4 Ni 6 Al 23 Ce 3 Al 11 + NiAl 3 U 3 : L + CeNiAl 4 Ce 4 Ni 6 Al 23 + Ce 3 Al 11 P 1 : L + CeNiAl 4 + CeNi 2 Al 5 Ce 4 Ni 6 Al C [736 C] 896 C [896.5 C] 990 C [998 C]

18 Sm-Ni-Al: Al: isothermal section at C 1.Sm4Ni6Al23 2.Sm3Ni5Al19 3.SmNiAl4 4.SmNiAl3 5.SmNiAl2 6.SmNi2Al3 7. Sm13Ni30Al57 Grey phase: Sm4Ni6Al23 Bright phase : SmAl3 liquidus Bright phase: Sm3Ni5Al19 Grey phase: NiAl3 Light grey phase: Ni2Al3 Bright phase: SmAl2 Dark Grey phase: SmNi2Al3 Light grey phase: SmNiAl2 Grey phase: NiAl Light grey phase: SmNiAl4

19 -The existence of the Sm 4 Ni 6 Al 23, SmNiAl 4, SmNiAl 3, SmNiAl 2 and SmNi 2 Al 3 ternary phasespreviously reported for the isothermal section at 500 C were confirmed. -The existence of the Sm 3 Ni 5 Al 19 in samples annealed at 800 C was also confirmed. -A new phase with a composition ~Sm 13 Ni 30 Al 57 was found. - The relationships between binary and ternary phases have been proposed.

20 500 C 800 C

21 Ce-Ni-Al and Sm-Ni-Al systems: Isothermal sections at 800 C 1.Ce 4 Ni 6 Al 23 2.CeNiAl 4 1.Sm 4 Ni 6 Al 23 2.Sm 3 Ni 5 Al 19 3.SmNiAl 4 7. Sm 13 Ni 30 Al 57 Different behaviour of R-Ni-Al systems containing Ce or Sm But, the phase reported by [08Tang] to exist at 800 C with an unknown structure and a composition ~Ce 12.1 Ni 28.1Al 59.8 can be the same observed by us withacomposition~sm 13 Ni 30 Al 57

22 Conclusions -1 - Composition and crystal structures of the ternary phases Ce 4 Ni 6 Al 23, CeNiAl 4 wereconfirmed -FortheCe 3 Al 11 anisolubilityof~2at..% was observed. - The previously established phase relationships have been confirmed - Temperature of several invariant reactions have been determined by DSC and DTA analysis

23 Conclusions -2 - The existence of the ternary phases Sm 4 Ni 6 Al 23, SmNiAl 4, SmNiAl 3, SmNiAl 2 and SmNi 2 Al 3 previously reported for the isothermal section at 500 C were confirmed. The existence of the Sm 3 Ni 5 Al 19 in samples annealed at 800 C was also confirmed. - Anew phase with a composition ~Sm 13 Ni 30 Al 57 was found. Astructural investigation is still needed. - The relationships between binary and ternary phases have been proposed. - The differences between the relationships occurring at 500 C and 800 C have been highlighted. - Similarities and differences in the formation of ternary phases and in the established phase relationshipss for the Ce-Ni-Al and Sm-Ni-Al systems have been underlined.

24 THANK YOU FOR YOUR ATTENTION

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26 Al 15+4m Ni 4+m R 2+m structure series R 4 Ni 6 Al 23 R= Y, Sm, Gd, Yb Al RNi 3 Al 9 R= Y, Gd, Dy, Er R= heavy rare earths R 3 Ni 5 Al 19 R 3 Ni 5 Al 19 R= Gd RAl 3 NiAl 3 Phase R 4Ni 6Al 23 at% R at% Ni R 3 Ni 5 Al R 4 Ni 6 Al RNi 3 Al RNi 3 Al 9 at%al Ni 2 Al 3 structure type os108-gd 3 Ni 5 Al 19 ms66- Y 4 Ni 6 Al 23 hr78- ErNi 3 Al 9

27 Bright phase: Sm 3 Ni 5 Al 19 Grey phase: NiAl 3 liquidus Bright phase: SmNiAl 4 Dark Grey phase: new phase Grey phase: SmNiAl 3