Effects of VIM frequency on chemical composition,homogeneity and microstructure of NiTi shape memory alloy

Abstract

The concentration distribution and microstructure of NiTi shape memory alloys produced in vacuum induction furnaces operating at high and medium frequencies are compared with those of materials melted in vacuum resistance furnaces. The production procedure consisted of charging pure metals into a graphite crucible; raising the temperature to 1450°C under vacuum; holding the materials in high and medium frequency induction and resistance furnaces for 3, 5, and 120 min under vacuum; and allowing alloys to solidify in the crucibles under the same vacuum. The procedures in each of the three furnaces were made as similar as possible. Chemical composition, microstructure, and surface hardness of alloys were determined at different locations along the length of solidified specimens. Standard deviations in chemical analyses and hardness numbers were taken as criteria for specimen homogeneity. Results indicate that a high vacuum induction furnace operating at medium frequency is an appropriate equipment for melting NiTi shape memory alloys of the desired homogeneity, microstructure, and hardness.

Keywords

TINI SHAPE MEMORY ALLOY HOMOGENEITY VACUUM INDUCTION MELTING VACUUM RESISTANCE MELTING

Get full access to this article

View all access options for this article.

References

KUFMAN

: ‘Shape memory effect in alloy’, 1975, New York, Plenum Press.

SCHOTKY

M. D.

: Trans Mater. Res. Soc. Jpn. B, 1994, 18B, 1131–1141.

ABRAHAMSSON

and BJAMEMO

: Trans Mater. Res. Soc. Jpn. B, 1994, 18B, 1171–1174.

IGHARO

and WOOD

J. V.

: Powder Metall., 1985, 28, 131–139.

HONMA

M. NISHIDA and K. YAMAUCHE ‘Ti—Ni alloy articles having a property of reversible shape memory and a method of making the same’, Pat. 4707196, US Patent Office, Washington, DC, November 1987.

GREEN

S. M.

, GRANT

D. M.

and KELLY

N. R.

: Powder Metall., 1997, 40, 43–47.

B.-Y.

, RONG

L.-J.

, LI

Y.-Y.

and GIUNTER

V. E.

: ThterilletalliCS, 2000, 8, 881–884.

GOLDSTEIN

and SCOTT

: ‘Melting method for high-homogeneity precise-composition nickel— titanium alloys’, Pat. 4282033, US Patent Office, Washington, DC, 1981.

SCOTT

: ‘Gamma titanium aluminide production using the induc-tion skull melting process’, 475 — 482; 1995, Warrendale, PA, TMS.

10.

BADAKHSHAN RAZ

: ‘Influential parameters in production of Ni—Ti memory alloy via melting-casting method’, MSc thesis, Sharif University of Technology, Tehran, Iran, 2002 (In Persian).

11.

ROZNER

A. G.

, HEINTZELMAN

E. F.

, BUEHLER

W. J.

and GILFRICH

J. V.

: ASM Trans., 1965, 58, 415–418.

12.

ZARANDI

F. M. H.

and SADRNEZHAAD

: Mater. Manuf Process., 1997, 12, 1093–1105.

13.

SADRNEZHAAD

, MASTIFIADI

and R. SHARGHE Mater. Manuf Process., 1997, 12, 107–115.

14.

DUERING

T. W.

and PELTON

R. A.

: ‘Ni—Ti shape memory alloy, material properties handbook: titanium handbook’, 1994, Metals Park, OH, ASM International.

15.

MIRABOLGHASEMI

S. H.

, SELAHI

, HAERI

and SADRNEZHAAD

S. K.

: ‘13th Iranian Foundrymen's Society confer-ence’, 237–244; 2001, Tehran, Iran (In Persian).

16.

LOPEZ

H. F.

, SALINAS-RODRIGUEZ

and RODRIGUEZ-GALICIA

J. L.

: Scr. Mater., 1996, 34, 659–664.

17.

ISHIDA

, SATO

, TAKEI

, NOMURA

and MIYAZAKI

: Metall. Mater. Trans A, 1996, 27A, 3753–3759.

18.

LIU

X. P.

, CM

, ZHANG

C. S.

, HE

X. Y.

and ZHAO

L. C.

: Trans. Mater. Res. Soc. Jpn. B, 1994, 18B, 1121–1124.

19.

MASSALSKE

in ‘Binary alloy phase diagrams’, (ed. Murray

J. L.

et al), 2847; 1986, Metals Park, OH, ASM International.

20.

FAVIER

, tau

and MCCORMICK

P. G.

: Scr. Metall., 1993, 28, 669— 672.

21.

THIER

, TREPPMANN

, DRESCHER

and BOUREAUL

: J. Mater. ScL: Mater. Med., 1992, 3, 229–233.

22.

ALLAFI

J. K.

, REN

and EGGLER

: Acta Mater, 2002, 50, 793— 803.

23.

WASILEWSKI

R. J.

, BUTLER

S. R.

and HANLON

J. E.

: Metall. Trans. A, 1971, 2A, 229–238.

24.

CHOUDHURY

: ‘Vacuum metallurgy’, 1990, Materials Park, OH, ASM International.

25.

FURUYA

, KIMUR

, MATSUMOTO

and MASUMOTO

: Trans. Mater. Res. Soc. Jpn. B, 1994, 18B, 1033–1036.

26.

ZINN

and SEMIATIAN

S. L.

: ‘Elements of induction heating’, 3rd edn, 1991, Palo Alto, CA, Electric Power Research Institute.

27.

FELEMINGS

M. C.

: ‘Solidification processing’, 1974, New York, McGraw-Hill.

28.

DAVIS

G. J.

: ‘Solidification and casting’, 1973, London, Applied Science.

29.

STEFANESCU

: ‘Casting metals handbook’, 9th edn, Vol. 15, 1988, Metals Park, OH, ASM International.

30.

TUDBURY

C. A.

: ‘Basics of induction heating’, Vol. 1, 1960, USA, New York, John F. Rider.

31.

YAMAGUCHI

and KAVASE

: 1st Int. Conf. on ‘Processing material for properties’; 1993, Warrendale, PA, TMS.

32.

GEIGER

G. H.

and PORIER

D. R.

: ‘Transport phenomena in metallurgy’, 1973, Reading, MA, Addison Wesley.

33.

ZSEKELY

and THEMELIS

N. J.

: ‘Rate phenomena in process metallurgy’, 1971, New York, Wiley.