1. Intermetallics as innovative CRM-free materials
Pavel Novak1, Lucyna Jaworska2, Marcello Cabibbo3
1 Department of Metals and Corrosion Engineering, University of Chemistry and Technology Prague, Technická 5, Prague. Czech Republic;
2 The Institute of Advanced Manufacturing Technology, Wroclawska 37A, Krakow. Poland
3 DIISM/Università Politecnica delle Marche, Via Brecce Bianche, Ancona, Italy

2. Outline Properties of intermetallics
Presented applications of intermetallics
High-temperature materials
Tool materials
Corrosion resistant materials
Biomaterials
Production of intermetallics

3. Properties of intermetallics
High melting points
High hardness
High resistence against high-temperature oxidation
Excellent corrosion resistance
Aluminides and silicides = low density
Shape memory
Hydrogen storage ability
Special magnetic or electric properties
… x
Low room-temperature ductility
Problematic production

4. Presented applications of intermetallics
Power generation
Automotive industry
Chemical industry
Aerospace industry
Medicine

5. High-temperature materials
Heat-resistant steels, nickel alloys, cobalt alloys
CRMs: Cr, Co, Nb, W
Applications:
Airplane jet engines
Car combustion engines (turbocharger, exhaust valves)
Furnace elements …

6. High-temperature materials
Turbine blades of airplane engines (Boeing 787, 747)
High-temperature oxidation (800°C, air)
P. Novák, et al., Intermetallics 19 (2011)

7. High-temperature oxidation (800°C)
Fe-Al-Si-Ni
High-temperature oxidation (800°C)
P. Novák, et al., Key Engineering Materials 465 (2011)

8. Tool materials
Cemented carbides, tool steels
CRMs: Co, W, Cr, (Mo)

9. Intermetallics as tool materials?
Hardness
Wear resistance

10. Short fibre- reinforced
NiAl-Al2O3 composites
Particle- reinforced
1 wt. %
10 wt. %
Short fibre- reinforced
1 wt. %
5 wt. %
P. Novák, et al., Powder Metallurgy 54 (2011),

11. NiAl-Al2O3 composites
P. Novák, et al., Powder Metallurgy 54 (2011),

12. Corrosion-resistant materials
Stainless steels, nickel alloys
Contain CRMs: Cr, (Mo)
Applications:
Chemical industry
Car exhausts
Kitchen tools
Other aggressive environments

13. Corrosion-resistant materials
Intermetallics based on Fe-Al system – passivation by Al2O3 at pH > 3
addition of Si – weaker passive layer at pH > 2
Intermetallics based on Ti-Al system – passivation by Al2O3 and TiO2 at pH > 2
addition of Si – less significant effect

14. Biomaterials Titanium alloys, cobalt alloys, stainless steels
Contain CRMs: Nb, Co, Cr, (Mo)

15. Bone replacement material
New Ti-Si based material
Human bone

16. Production - Melting metallurgy
high melting points (e.g. Ti5Si3 2130°C)
high reactivity of the melts
Ti-Al-Si alloy

17. Forming
possible for intermetallics which exhibit plasticity at elevated temperatures (TiAl, NiTi)
forming of Fe-Al a Fe-Al-C with the use of protective capsule
I. Schindler et al. / Intermetallics 18 (2010) 745–747

18. TiAl-Ti5Si3 composite (MA + SPS)
Powder metallurgy
Powder preparation:
melt atomization
mechanical alloying
Consolidation:
HIP (hot isostatic pressing)
SPS (Spark Plasma Sintering)
Advantages – fine-grained structure
Disadvantages – high costs, problematic sinterability of intermetallics
TiAl-Ti5Si3 composite (MA + SPS)

19. Powder metalurgy - Mechanical alloying
Joining of particles by plastic deformation
Severe plastic deformation  structure refinement
Formation of solid solutions and intermetallics
Crushing of particles
Usually long duration (10 – 100 h)
Ultra-high energy mechanical alloying (1 - 4 h)

20. Powder metalurgy - Spark Plasma Sintering
Spark Plasma Sintering (SPS)
uni-axial pressing + high electric current
ultra-rapid sintering
conductive and non-conductive materials
High Pressure SPS (HP SPS)
up to 8 GPa
lower porosity
modified mechanical properties
Ä. Knaislová, et al., Materials 10 (2017) 465

21. Self-propagating High-temperature Synthesis (SHS)
TiAl-Ti5Si3 in-situ composite
P. Novak et al., Powder Metallurgy 54 (2011)

22. SHS - „Thermal explosion“ mode
P. Novák et al., Powder Metallurgy 54 (2011)

23. Conclusions
Intermetallics are already substituting CRM-containing materials in selected applications (jet engines,...).
For more wide use, the extensive development is needed.
Positive reaction from industry required.
Acknowledgement
The international frame of the research was supported by COST Action CA15102.