EXPLOSIVE PRODUCTION OF ULTRAFINE-GRAINED MATERIALS

1. EXPLOSIVE PRODUCTION OF ULTRAFINE-GRAINED MATERIALS Yu. A. Gordopolova, S. S. Batsanova, V. A. Veretennikova, N. G. Zaripovb, and L. V. Gordopolovaa aInstitute of Structural Macrokinetics and Materials Science, Chernogolovka, Moscow, 142432 Russia bState Aviation Technical University, Ufa, 450000 Russia e-mail: gordop@ism.ac.ru Contents • Shock compression of nanopowders • Dynamic-isostatic pressing of ultrafine powders •Shock-induced refining of grains in materials •Shock quenching of SHS products • Conclusion

2. SHOCK COMPRESSION OF NANOPOWDERS I II D D Pressing with cylindical geometry ED Decaying mode (underpressing) Regular mode(homogeneity) Mach mode (overpressing) HE P = 0 DU D = c0 + bU ampoule(ductile metal) starting powder PI ~ D2; PII ~ D2 PI > PII plug → Resultant monolith material (Ni)after shock compaction and thermal treatment (6OOC, 15 min) mean particle size < 100 nm hardness 47 HRC bending strength 1100 MPa starting powder (Ni) mean particle size 56 nm TEM photograph of final Ni sample

3. DYNAMIC-ISOSTATIC PRESSING OF ULTRAFINE POWDERS ED HE ampoule(steel) KBr foil starting powders (diamond/w-BN) → final compact (diamond/w-BN) grain size in central area 10 nm hardness 8103 HV grain size at periphery30 nm hardness(2-3)103 HV compression strength (until cracking) 10 t/cm2 particle size (polycryst.)3-10 m size of single crystals in particles < 100 nm

4. SHOCK-INDUCED REFINING OF GRAINS IN METALS(dynamic recrystalization) Microstructure of Al—4% Cu—0.5% Zr mixture at different depth from the surface of loading 5 mm 7 mm

5. F REFINEMENT OF CERMET GRAINS DURING HOT DEFORMATIONExperimental setup rapid deformation (dynamic loading) slow deformation (quasi-static loading) ED lens punch HE D metal matrix shock wave (103m/s) initial sample (TiC0,47 SHS compact at 9500C) force (10 ton) ~ 106 s-1 ~ 0.1 = 10–4–10–3 s–1 = 0.7–0.8 final shape of samples

6. MICROSTRUCTURE OF TITANIUM CARBIDE SUBJECTED TO RAPID HOT DEFORMATION (SHOCK COMPRESSION) (b) (a) (c) (d) Microstructure of (a) starting TiC0.47and (b–d) its evolution during rapid (dynamic) hot deformation (high ).

7. MICROSTRUCTURE OF TITANIUM CARBIDE SUBJECTED TO SLOW HOT DEFORMATION (SUPERPLASTIC MODE) Microstructure of TiC0.6 obtained by superplastic (quasi-static) deformation of TiC0.47 (low )

8. 4.325 Lattice parameter, Å TiC0.75 4.320 4.315 TiC0.6 4.310 TiC0.58 TiC0.55 4.305 4.300 4.295 TiC0.47 4.290 0 0.25 0.50 0.75 1.00 Strain , rel. units CHEMICAL COMPOSITION OF TITANIUM CARBIDE GRAINS DURING HOT DEFORMATION Lattice parameter of TiCx vs. strain  for dynamic (□) and quasi-isostatic (○) loading

9. FINE STRUCTURE OF TITANIUM CARBIDE DURING RAPID HOT DEFORMATION (a) (b) (c) Changes in the fine structure of TiCx during hot deformation: (a) development of intergranular sliding, formation of dislocation walls and subgrains, (b) precipitation of tabular Ti, and (c) formation of fine-grained microduplex structure.

10. SHOCK QUENCHING of SHS PRODUCTS 100 1.2 C/Ti = 0.47 C/Ti = 0.76 C/Ti = 1.00 C/Ti = 1.00 Detonation delay, s 1.0 C/Ti = 0.47 C/Ti = 0.76 C/Ti = 1.00 C/Ti = 1.00 90 Relative density, % Mean grain size, m 0.8 0.6 80 120 240 360 120 240 360 0 0 ED HE Highly dense materials with controlled grain size Flying plate Green mixture Container Igniter TC Plug Detonation delay, s

11. R/Rmax 1.0 0.8 0.6 0.4 0.2 Ti ( ), C ( ), Si ( ), Cu ( ) GRADED AND LAYERED MATERIALS BY SHOCK QUENCHING OF SHS PRODUCTS Combustion wave Combustion wave Ti + C Cu Ti + Si TiSi Ti + Si product green mixture reaction zone d, m 10 8 6 4 2 0 50 100 L, m TiC Cu TiSi

12. CONCLUSION Action of shock waves on materials is an effective tool for modification of their structure and hence properties. Different options for application of shock waves afford preparation of different materials with unique properties, including ultrafine-grained and nano-structured ones, for various practical implementations.