Review on Fabrication Methods of in situ Metal Matrix Composites By: 1. LAW MEI LINB BMFB1 2. MOHD AQHAIRI BIN BAHARI B BMFB2 3. MOHAMAD IZZUDIN BIN ABDUL HAMID B BMFB1 4. NOOR AYUHAAN BINTI ABD LAH B BMFB1 5. RIANAH BINTI JIREN B BMFB2 6. SITI SAINILLAH BINTI SULAIMANB BMFB1 7. NADIAH BINTI JAAFAR B BMFB1 1

What is In Situ? In situ is a Latin phrase which translates literally to 'In position'. 2

What is in situ techniques? Involve a chemical reaction resulting in the formation of a very fine and thermodynamically stable reinforcing ceramic phase within a metal matrix. 3

Advantages of in situ techniques 1.There is thermodynamic compatibility at the matrix-reinforcement interface. 2. Also, the reinforcement surfaces are likely to be free of contamination. ~ Therefore, stronger matrix- dispersion bond can be achieved. 4

Technologies 1.Powder Metallurgy Method (Fabrication of in situ Fe/TiC) 2.Liquid-Gas Reaction (Fabrication AlN/Al composite) 3.Solid-Gas-Liquid Reaction Method (Formation of fine single crystal TiC platelets in the Al based matrix ) 4. In situ – Processed by Ingot Metallurgy (Fabrication of Al-TiC composites) 5.Plasma Metallurgy Method 5

In situ – Processed by Ingot Metallurgy What it means? in which the solidification process where the reinforcing particles are formed in situ in the molten alloy. Attractiveness: 1.Simplicity 2.Economy 3.Flexibility 6

In situ – Processed by Ingot Metallurgy 1.Tong and Fang (1998) fabricated Al-TiC composites: with refined microstructure, enhanced dispersion hardening of the reinforcing phases 7

Process 8

Ingot Metallurgy (Synthesis of composites) Al (99.9%) + Ti (99.7%) Graphite powder (40-50 μm) Heated 1100 °C – 1200°C 1h 1300 °C – 1400°C 10 minutes Mixture direct chill cast into ingot bars Melt in graphite-lined induction furnace with argon gas flow. 9

Diagram Example of Ingot Metallurgy 10

Rapid solidification (by chill block melt spinning) The resultant ribbon form The wheel rotating with a surface velocity (30m/min) (solidify process) Melt was ejected to the surface copper rotating wheel by using argon gas When the temperature achieve at 1350 °C, and hold for 5 minutes Heated using high frequency induction 20g of master material was contained in a crucible 11

Video (chill block melt spinning) 12 Ribbon shape

Chemical Analysis The analysis of master ingots was done by the wet method. Carbon was determined by using automatic combustion apparatus. 1.Sample is combusted in a stream of oxygen and the carbon of specimen is converted into CO 2. 2.The CO 2 is fed into a measuring chamber where the concentration peak is detected with nondispersive spectrometer. 3.The linear signal is integrated and displaced digitally after weight compensation and blank correction. 13

Stream of oxygen ChamberDetection with a nondispersive spectrometer AUTOMATIC COMBUSTION APPARATUS 14

Applications 15

MMC by IN SITU FABRICATION METHOD. Short-fiber reinforced in situ MMCShort-fiber. Long-fiber reinforced in situ MMCLong-fiber. Particulate in situ MMCParticulate 16 As a general….

IN SITU MMC APPLICATIONS Rapid Solidification Process Ex : TiC particulate- reinforced Al Rapid Solidification Process Ex : TiC particulate- reinforced Al Vapor phase Infiltration Ex : Silica base aerogel/transition metal composite Vapor phase Infiltration Ex : Silica base aerogel/transition metal composite Controlled crystallization Ex : magnetic device such as choke coils & transfomers Controlled crystallization Ex : magnetic device such as choke coils & transfomers 17

APPLICATIONS OF IN SITU 1) Aerospace  In the aerospace industry, equipment on-board aircraft must be tested in situ, or in place, to confirm everything functions properly as a system 2) Petroleum production  In situ refers to recovery techniques which apply heat or solvents to heavy oil or bitumen reservoirs beneath the earth's crust. 3) Experimental Physics  In situ refers to a method of data collection or manipulation of a sample without exposure to an external environment. 4) Biology  In situ means to examine the phenomenon exactly in place where it occurs (i.e. without moving it to some special medium).

Additional Information 19

In-Situ Polymerization In-situ polymerization has been used to prepare nanocomposites. Inorganic nano-particles are dispersed in monomer, followed by heat or other treatment of the reaction mixture to induce polymerization. Advantages of in-situ polymerization technique: 1.Uniform CNT dispersion in monomers 2.Polymer chains grafted onto the convex walls of carbon nanotubes during in-situ; thus CNT homogeneously dispersed in polymer matrix. 20

Advantages: (cont.) 3. Important for the preparation of insoluble and thermally unstable polymer composites, which cannot be processed by solution or melt processing. 4. For preparation of polymer composites with high nanotube loading, in-situ provides very good miscibility with almost any types of polymers. 21

In-situ polymerization methods used to fabricate CNT- PMMA composites by incorporating CNTs during the course of polymerization of MMA. Basic starting materials: 1.Nanotubes 2.MMA monomer Method: In-situ free radical polymerization method involves polymerization of monomer using a radical initiator such as 2.2´-azobisisobutyronitrile (AIBN). CNTs are dispersed through ultrasonication in the prepolymer. 22 In-Situ Polymerization Processing

Adding CNT at prepolymer provides good dispersion in the low viscosity of the prepolymer. As the polymerization progresses, the viscosity of the solution increases and the polymer grows and wraps around the dispersed CNTs. Benefits: a)Higher interfacial strengths as CNTs interact with the growing polymer, thus forming stronger CNT-polymer bonds via non-covalent or covalent interactions. b)Composites with enhanced mechanical, electrical and tribological were obtained. 23

For another research of MWCNT-PMMA composites synthesized by in-situ bulk polymerization usig AIBN as free radical initiator, the microstructure are shown in Figure A below. 24 Figure A: Microstructure of the in-situ facricated MWCNT-PMMA composite. The bright masses indicates CNTs wrapped with PMMA layers

Q & A 25

1. What is the criteria for reinforcement selection? In general, There are necessary criteria or conditions that must be satisfied for the selection of a ceramic as reinforcement in the manufacture of good and standard metal matrix composites. Such criteria include density, melting temperature, size and shape, elastic modulus, tensile strength, thermal stability, compatibility with matrix material, coefficient of thermal expansion, and cost.

2. Why choose Ti and Al for the In-situ processed by Ingot metallurgy? In general, selection of metal or its alloy as matrix for production of MMC depends on the type, required properties and the kind of application where such composite is required. From this experiment, Al based and Ti based metal matrix composites have a high potential for advanced structural applications when high specific strength as well as good elevated temperature resistance.

3. Why the particulate reinforced MMCs are more interesting due to their ease of fabrication, low costs, and isotropic properties? Answer : The properties of MMCs are controlled by the size and volume fraction of the reinforcement phase as well by the nature of the matrix reinforcement interface 4. In traditional MMCs, wetting between molten metal and reinforcements is often poor. How this problem can be treated? Answer : This problem can be treated through a strongly reactive alloying addition, such as Mg and Li and through reinforcement coating.

5)How do we know if MMC is a hybrid composite? 6)What do you have in mind about in situ hybrid composite? A metal matrix composite (MMC) is composite material with at least two constituent parts, one being a metal. The other material may be a different metal or another material, such as a ceramic or organic compound. When at least three materials are present, it is called a hybrid composite. Scientist do hybrid to pick up good qualities. So there are 2 things better in something they try to mix and make a best item. For e.g. some flower have good looks but no smell and other have great smell but dull look so they mix and try to make a flower with great look and smell together. The authors suggest that it may name as in situ hybrid composite because: 1)It can be achieved in a short processing time 2)Many kinds of ceramic powder can be put into alloy liquid