1. Shaping Characteristics and Solidification Microstructure under Electromagnetic Confinement for Nickel-Based Superalloys Lin Liu State Key Laboratory of Solidification Processing Northwestern Polytechnical University Xi’an 710072, PR China, E-mail: linliu@nwpu.edu.cn

2. 1. Background

3. 3 Turbine blades in Aero-engine CC DS SC

4. 4 Manufacture process of engine blades Ceramic mold CCDS SC Molten metal

5. 5 Liquid metal cooling directional solidification process Disadvantage of physical molds: Reacting with the melt and polluting it; Separating the samples from cooling medium, resulting in lower cooling rate during solidification

6. 6 EMCDS Electromagnetic pressure Solidification structure control Electromagnetic Confinement and Directional Solidification (EMCDS)

7. 7 1-solid alloy,2-heating inductor,3- shaped melt,4-shaping inductor ， 5-solidfied sample, 6-screen,7-coolant, 8-cooler, 9-drawing bar ， 10-thermal coupler ， 11-recorder  Characteristics :  Contact less and no contamination  High temperature gradient and high cooling rate Electromagnetic Confinement and Directional Solidification Process (EMCDS)

8. 2.Theoretical Models and Simulation

9. 9 Electromagnetic Pressure under Dual- frequencies P m =P m1 +P m2 +P m12 +P m21 If frequencies difference is an integer, the last two items can be neglected:

10. 10 Electromagnetic pressure under difference parameters Melt height Frequency Magnetic induction intensity Electromagnetic parameters of materials

11. Electromagnetic Pressure variations at the corner r=20mm r=10mm r=5mm r=4mm r=3mm r=2mm

12. Electromagnetic Pressure Distribution of rectangle cross- sections under different width-thickness ratios (r=5mm) 1:1 2:1 3:1 4:1 （

13. 13 sample a=b=c=6.5mma=9mm,b=7mm,c=6.5mma=10mm,b=8mm,c=6.5mm Design of Inductor

14. 14 3-D temperature and electron- magnetic force field

15. 15 z S/L d S L H Flatness (d) of S/L interface varies with the liquid column height (H)

16. 3. Experimental

17. 17 EMCDS equipment

18. 18 Samples of EMCDS （ Aluminum alloys, Stainless steels, Superalloys ）

19. 19 Macrostructure of a superalloy with electron-magnetic confinement With convection Less convection

20. 20 Dendritic morphology and spacing V=120μm·s -1 300μm Effect of drawing velocity on dendritic spacing

21. 21 The application of EMCDS Active metal and alloys –Intermetallic compounds: TiAl –Magnetic alloys: NdFeB, SmCo High melting point alloys –NiAl (1640 ℃ ) –Nb 5 Si 3 (2000 ℃ )

22. 22 4. Conclusions A new kind of material forming technique was introduced, that is electromagnetic confinement and directional solidification (EMCDS). The theoretical models of EMCDS process are put forward. Enough electromagnetic pressure exerted to samples and proper values of the ratio of heat to force are required for shaping the given materials and predetermined cross sections in dual-frequency magnetic field. The samples of various alloys, such as superalloys and aluminum alloys were obtained with containerless electromagnetic shaping process with directionally solidified structure.

23. Thanks for your attention