RAPID SOLIDIFICATION OF LIGHT ALLOYS (Al & Mg)

PREPARED BY: MD BAZLUR RASHID

ID: 500482015

Prepared for: Professor Ravi Ravindran

� Introduction

� “Conventional casting Techniques”

Session overview

� “Rapid solidification casting techniques”

� “Conclusion”

� Light alloy: The alloy which have higher strength ration than

iron or nickel based structural alloys is called light alloy (Web

definition).

� The specific strength ration of Mg =25.3 GPa , Al=26.7 GPa ,

Introduction

� The specific strength ration of Mg =25.3 GPa , Al=26.7 GPa ,

and for Ti = 26.6 GPa , these metal based alloys are noted

as light alloy.

� Al, mg and Ti based alloys are more attractive in the

aerospace industries because of their attractive structural

weight reduction phenomenon.

Light alloys are widely used in:

� Air craft and rocket design

Application of light alloys

� Air craft and rocket design

� Shipbuilding

� Transportation Engineering

� Electrical Engineering

� Production of consumer goods

� Military application.

Conventional casting method

� The process contains a hollow

cavity of desired shape to be

solidified.solidified.

� Solidification includes: surface

formation, local gap formation,

heat flow and cooling system,

microstructure of the skin, hot

tears etc.

� Solidification differs based on

the pure metal and alloys.

Figure : A typical casting Mold

� “The Rapid solidification (RS) process has been widely used since 1984”.

There are many kinds of rapid solidification process have been

Rapid solidification Technology

There are many kinds of rapid solidification process have been developed in the past like:

• Vacuum Induction melting

• Squeeze casting

• Splat quenching

• Melt spinning

• Planer flow casting

• Laser or electron beam solidification.

RST ( Continued)

� VAC is on of the pioneer in rapid

solidification Technology to cast

thin metallic ribbons of thickness

15- 50µm in a single process step

directly from molten metal.directly from molten metal.

� Extremely high cooling rates of

10^6 k/s.

� High casting speed of 100 Km/hr.

� In- line winding up of the thin

ribbon.

� Automatic reel change during

winding without process

interruption. Figure: Vacuum induction melting

� Magnesium is the lightest structural material with an

attractively feature of low density 1.74 gm./ cm^3

Properties and phase diagram of Mg

attractively feature of low density 1.74 gm./ cm^3

� The magnesium is 36% lighter than Aluminum and 61.3%

lighter than titanium.

� Rapid solidification of magnesium alloys has two objectives:

the improvement of corrosion resistance and balancing of

compressive and tensile yield strength which are the

overcoming of conventionally processed magnesium alloys.

� The study on RS, Mg - 8.5 wt. % Li + 1 wt. % Si

RS effects on Magnesium Alloy

� The study on RS, Mg - 8.5 wt. % Li + 1 wt. % Si

exhibited microstructural refinement in the RS scales of

the binary alloy by a factor of 10 related with chilled-cast

material.

� Recent study on melt spun ribbons process, Mg- Al - Zn

alloys containing with rare earth additions reported very

fine grain refinement microstructure (grain size 0.3- 0.7

µm) .

RS of Mg Alloy

� Grain refinement is more uniform, and unique in RS than ingot system.than ingot system.

� During extrusion and heat treatment precipitation formed which made nearly doubled the yield strength of Mg- 0.3 wt. % Zr and increased it ultimate strength by 30%. Figure:- (4) Scanning electron micrographs of

(a) ingot and (b) splat specimens of Mg -10

wt. % Nd alloy showing of refinement .

� The density of aluminum is 2.70 g / cm^3.

� Because of acceptable cost, low component mass, appropriate

mechanical properties and structural integrity, 70% of

Properties and Phase diagram of AL

mechanical properties and structural integrity, 70% of

commercial and civil air frames are made from aluminum alloy.

� Al- alloy used in commercial vehicles, marine hulls and

superstructure, military vehicles.

� Car industry use aluminum alloy as engine castings, wheels,

radiators and increasingly as body parts.

� More over it is widely used in electrical conductors and food

packaging (foil paper).

RS effects of Al alloy

� Enhance mechanical

properties because of fine

grain structure formed by grain structure formed by

Rapid solidification.

� Low shrinkage and gas

porosity.

� Good surface quality

RS of Al alloy ( Contd.)

∗ Rapid solidification can reduce interdendritic shrinkage which is an overcoming of IM process. It makes overcoming of IM process. It makes uniform and finer grain distribution.

∗ With addition of earth metals, RSP can increase corrosion resistance due to microstructural refinement.

∗ Rapid solidification has been employed to produce very fine size grain alloys for which tensile and compressive yield strength are almost equal.

Interdendritic shrinkage in aluminum alloy.

Conclusion

∗ Ultimate tensile strength increased to 730 MPa by RS which is 600 MPa during IM for certain type of aluminum alloy (Al-6.5 Zn-2.5 Mg- 1.5 Cu- 0.14 Zr-0.1 Ni). 400

600

800

aluminum alloy (Al-6.5 Zn-2.5 Mg- 1.5 Cu- 0.14 Zr-0.1 Ni).

∗ Investigation on intermetallic compound base aluminum has started and in future more potential will be provided for its high temperature use.

∗ Rapid solidification of Mg alloy has improved its strength, ductility, corrosion resistance and thermal stability.

0

200

400

Fig: comparison of Ultimate tensile

strength.

∗ [1]. YOUNG-WON KIM and S. KRISHNAMURTHY: Rapid Solidification of Lightweight Metal Alloys*, Materials Science and Engineering, A 117 (1989) 19 – 32.

∗ [2]. Loren A. Jacobson, Joanna McKittrick: Rapid solidification processing, Materials Science and Engineering R11 (1994) 355- 408.

∗ [3]. Amit Joshi, LITHIUM ALUMINIUM ALLOYS –The New Generation Aerospace Alloys.∗ [4]. M.P. Groover, “Fundamentals of modern manufacturing,” 3rd edition, (2007).∗ [5]. Dr. Talib Khalel Ibrahim*,Dr. Ali Sabea Humod**: Rapid Solidification Processing of Al- 3wt% Mg Alloy, Eng. & Tech.,

Vol.25, No.10, 2007∗ [6]. Metals Handbook, 9th edition, vol. 16, ASM International, Materials Park, Ohio, 1989.∗ [7]. W. Kurz, R. Trivedi: Rapid solidification processing and microstructure formation, Materials Science and Engineering,

A 179/A180 (1994) 46-51

Reference

A 179/A180 (1994) 46-51∗ [8]. Rapidly solidify aluminum alloys key to metals.∗ [9]. Rapid solidificatification process (Wikipedia)∗ [10] L.A Carapela, Met. Prog,. 48(1947) 297-307∗ [11]. F. Hehmann, F.sommer and H. Jones, in E.H. Fores and S.J. Savage ( eds.), Progressing of structural metals by Rapid

solidification, American society for metals, Metals park, OH,1987, pp. 397-398.∗ [12]. N.I. Varicch and B.N. Litvin, fiz. Met. Metalloved, 16 (4) (1963) 526-529∗ [13]. H. Abe, K. Ito and T. Suziki, Acta metal., 18(1970) 991-994∗ [14]. H. Abe, K. Ito and T. Suziki, trans. Jpn. Inst. Met., 11 (1970) 368-370.∗ [15]. H. Abe, K. Ito and T. Suziki, J.Fac. Eng. Univ. Tokyo, A10 (1970) 60-61∗ [16]. R.S. Busk, Light Metals, 23 (266) (1960) 197-200.∗ [17]. P.J. meschter and J.E O’ Neal, Metal. Trans. A, 15 (1984) 237-240.∗ [18]. C.F. Chang, S.K. Das and D. Raybould, in P.W. Lee and R.S.Carbonara (eds.), rapidly solidified materials, American

society for metals, Melts Park, OH, 1985, pp. 129-135.∗ [19]. R.S. Busk and T.E. leontis, trans. Metal. Soc. AIME, 188(1950) 297-306.∗ [20].T.R. Anantharaman et all. Trans. Ind. Inst. Met., 30 (6) (1977) 1-13∗ [21]. H. Jones, Rapid solidification of Metals and Alloys, Monograph No. 8, Institution of metallurgies, London. 1982.∗ [22]. M. Lebo and N.J. Grant, Metall. Trans., 5 (1974) 1547-1555.∗ [23].J.E. Hatch (ed.), Aluminum: properties and physical metallurgy, American society for metals, Metals Park, OH, 1984.