# Fabrication of Aluminium Metal Matrix Composite and
Testing of Its Property

S Johnyjames, A Raja Annamalai

► To cite this version:

S Johnyjames, A Raja Annamalai. Fabrication of Aluminium Metal Matrix Composite and Testing of Its Property. Mechanics, Materials Science & Engineering MMSE Journal. Open Access, 2017, 9, 10.2412/mmse.62.86.695. hal-01504692

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# Fabrication of Aluminium Metal Matrix Composite and Testing of Its Property

S. JohnyJames¹,ª, A. Raja Annamalai¹

1 – School of Mechanical Engineering, VIT University, Vellore, 632014, India

a – johnyjames2002@yahoo.com

<figure><img src="image_2.png" /></figure>

DOI 10.2412/mmse.62.86.695 provided by [Seo4U.link](https://seo4U.link)

**Keywords:** metal matrix composite, stir casting, tensile strength, wear, Zirconium silicate.

**ABSTRACT.** In this paper an attempt has been made to fabricate aluminium metal matrix composite using a newly emerging reinforcement Zirconium silicate which is also called as Zircon (ZrSiO₄). The metal matrix selected was Al-6061. The composition of reinforcement with the metal matrix is 10 wt percent. Stir casting bottom pouring technique was chosen to fabricate the composite. From the cast specimen various samples were cut to study its mechanical and tribological property after the addition of reinforcement. The optical and SEM image shows the presence and dispersion of reinforcements in the metal matrix phase. The spectrum processing was carried out and the result confirms the presence of Zirconium, Silicon, oxygen and aluminium. The Vickers hardness test shows elevated hardness value due to the addition of reinforcement ZrSiO₄ and its value is 101.1HRC. The tensile specimens were prepared using wire-EDM process as per ASTM-E8 standard. The tensile value reveals that there was an improvement in tensile strength of composite and its value is 0.094Gpa. Also, fractography study was done using scanning electron microscope to understand the causes of failure of specimen. Wear test was carried out on the composite using a linear reciprocating tribometer. The wear test result confirms high wear resistance due to the addition of ZrSiO₄ reinforcement in aluminium matrix.

**Introduction.** Composites material has high stiffness and high strength, low density, improved wear resistance, etc. When designed precisely, the newly combined materials produce enhanced strength than would each individual material. The addition of ceramic particles like SiC, Al₂O₃, B₄C, Al₂O₃ to an aluminum based matrix does not much alter the density of material but instead it usually leads to a considerable rise in strength and modulus of composite. Alaneme, studied the mechanical behaviour of alumina reinforced with 6063 metal matrix composite developed by two step – stir casting process. AA 6063– Al₂O₃ particulate composites having 6, 9, 15, and 18 volume percent of reinforcement were produced.[1] Sreenivasan fabricated TiB₂/Al metal matrix composites by stir casting route with 5, 10 and 15% of TiB₂ and studied the wear behaviour of composite. It was observed that the wear rate was higher for the unreinforced aluminium alloy when compared to the reinforced composites. Wear rate was decreased with increasing TiB₂ content in the MMC composites[2]. The composite fabricated using stircasting technique exhibit uniform distribution. Result of uniform distribution of reinforcement in the metal matrix confirm elevated mechanical behavior[3]. Also addition of reinforcements like Al₂O₃, SiC, TiB₂ in the metal matrix improves hardness and thermal property [4]. It has been observed that, elongation decreases when the percentage reinforcement increases, but tensile and hardness value will be high[5,6]. The homogeneity of reinforcement and uniform distribution of reinforcement particles in metal matrix depend upon stir casing parameters [7]. From the literature review it was noted that the most commonly used abrasive reinforcement with aluminium matrix are SiC, Al₂O₃, B₄C and TiB₂ and not much published literature on Zirconium silicate as reinforcement. Hence, in this paper an attempt has been made to fabricate aluminium metal matrix composite with Zirconium Silicate as reinforcement material and to study metallurgical,
tribological and mechanical behavior of developed composite material.

## II. Experimental Procedure

The reinforcement selected for the present study was Zirconium Silicate because of its unique material property and high hardness value about 7.5-8.0 Mohs Hardness at 20°C. Zirconium silicate is highly resist corrosion by alkali materials. The average particle size of Zirconium Silicate was 35 microns. The composites were prepared with 10 wt. % of Zirconium silicate. The aluminium matrix material selected was Al6061 which supports casting process. The Zirconium Silicate particles were preheated at 450°C for 60 min to improve the wettability by removing moisture. The furnace temperature was set to 840°C to melt the aluminium alloy. Continuous stirring of molten aluminium at 450 rpm lead to formation of vortex. The preheated reinforcements were gently added into the molten alloy upon the vortex. Both aluminium alloy and reinforcement material was held in the crucible for 7 minutes and continuously being stirred in order to gain uniform distribution of reinforcement in the matrix. Through bottom pouring arrangement the molten metal was poured into the die and solidified. The required test specimens for microstructure analysis, hardness test, tensile test and wear test were cut from the cast composite using wire-EDM process.

## III. Results and Discussion

### 3.1 Micrograph and analysis

The specimen for microstructure analysis was polished and the micrographs were captured using optical microscope and SEM. The microstructures have been thoroughly examined and found reinforcement particles were uniformly distributed in the metal matrix. Uniform distribution of reinforcement gives strength to the matrix and the same is the root cause for elevated mechanical property. Fig 1(a,b,c,d) shows the existence of reinforcement particles in the composite specimen. Few cluster formation were noticed and predicted this will cause reduction in mechanical property especially tensile strength.

<figure><img src="image_3.png" /><figcaption>Fig. 1, (a) SEM Micrograph of Al/ZrSiO₄.</figcaption></figure>

<figure><img src="image_4.png" /><figcaption>Fig. 1, (b) SEM Micrograph of Al/ZrSiO₄.</figcaption></figure>
<figure><img src="image_5.png" /><figcaption>Fig. 1, (c) Optical Micrograph of Al/ZrSiO₄.</figcaption></figure>

<figure><img src="image_6.png" /><figcaption>Fig. 1, (d) Optical Micrograph of Al/ZrSiO₄.</figcaption></figure>

## Spectrum processing:

<table><caption>Table 1. Elements present in the cast composite.</caption><thead><tr><td>Element</td><td>Weight%</td><td>Atomic%</td></tr></thead><tbody><tr><td>O K</td><td>1.07</td><td>1.79</td></tr><tr><td>Al K</td><td>97.69</td><td>97.18</td></tr><tr><td>Si K</td><td>1.01</td><td>0.96</td></tr><tr><td>Zr L</td><td>0.24</td><td>0.07</td></tr><tr><td>Totals</td><td>100.00</td><td></td></tr></tbody></table>

## Hardness test of Al6061 reinforced with ZrSiO₄

The Vickers hardness test was carried out using (Matsuzawa MMT-X) Vickers hardness machine with 500gf for 10 seconds. Five readings were taken with standard distance of app 0.5mm from every indentation to attain reliability in results. Diamond indenter is used for accuracy of results. The highest measured value is 101.1HRC. This confirms increase in hardness value. Hardness value has been increased due to the addition of ZrSiO₄ with metal matrix. During Composite fabrication reinforcement strengthens the metal matrix and the unique hardness property of ZrSiO₄ is transferred to the specimen.

<table><caption>Table 2. The hardness test value.</caption><thead><tr><th rowspan="2">Sl. No</th><th colspan="3">Measurement Position(mm)</th><th rowspan="2">Load</th><th colspan="2">Diagonal(µm)</th><th rowspan="2">Hardness HV</th><th rowspan="2">Conv. Scale</th></tr><tr><th colspan="3">X</th><th colspan="2">D1</th></tr></thead><tbody><tr><td>1</td><td>8.183</td><td>0.653</td><td>8.209</td><td>500</td><td>105.32</td><td>100.06</td><td>87.9</td><td>HRC</td></tr><tr><td>2</td><td>8.505</td><td>0.653</td><td>8.530</td><td>500</td><td>102.33</td><td>98.50</td><td>91.9</td><td>HRC</td></tr><tr><td>3</td><td>8.819</td><td>0.653</td><td>8.843</td><td>500</td><td>108.02</td><td>103.33</td><td>83.0</td><td>HRC</td></tr><tr><td>4</td><td>8.643</td><td>0.666</td><td>8.669</td><td>500</td><td>108.59</td><td>95.80</td><td>88.7</td><td>HRC</td></tr><tr><td>5</td><td>8.406</td><td>0.666</td><td>8.432</td><td>500</td><td>103.19</td><td>88.26</td><td>101.1</td><td>HRC</td></tr><tr><td colspan="6">Maximum value</td><td>101.1</td><td>HRC</td></tr></tbody></table>
## Tensile test

Three samples were made to have high reliability in results. The specimens were made as per ASTM-E8 standard. The tensile test was carried out using INSTRON tensile testing machine. The maximum Ultimate Tensile Strength value is 0.094Gpa. This elevated strength is achieved due to the addition of ZrSiO₄ with metal matrix. As per the microstructure analysis cluster formation was observed. This can cause degradation of mechanical property. Prevention or reduction of clusters during casting would have achieved higher tensile property. Tensile test shows the kind of fracture what happened is brittle fracture and this is due to reinforcement particles in aluminum matrix.

<table><caption>Table 3. The tensile strength of Composite.</caption><thead><tr><th>Weight % of reinforcements</th><th>SL.NO</th><th>Maximum Load (N)</th><th>UTS (GPa)</th><th>Modulus (Automatic Young's) (MPa)</th><th>Proof Stress (MPa)</th></tr></thead><tbody><tr><td rowspan="3">Al6061/ ZrSiO₄-10%</td><td>1</td><td>2499.77112</td><td>0.062</td><td>29574.066</td><td>58.15</td></tr><tr><td>2</td><td>2925.52710</td><td>0.073</td><td>36092.384</td><td>66.94</td></tr><tr><td>3</td><td>3784.77573</td><td>0.094</td><td>38323.753</td><td>78.04</td></tr><tr><td colspan="4">Maximum value</td><td colspan="2">0.094</td></tr></tbody></table>

## Fractography

It has been observed that uniform distribution of reinforcement in the metal matrix phase is one of the challenges encountered in metal matrix composite during processing which highly influence its strength. There are many factors constitute this issue. Settling of reinforcement particles in the bottom of crucible during holding time causes uneven distribution. This can arise as a result of density differences between the reinforcement particles and the metal matrix. The stirring blade design, rpm of stirrer too influence reinforcement distribution. Fig 2(a) & 2(b) shows pullouts during tensile test, which causes fracture of specimen predominantly in composites. This is due to the level of affinity between Al 6061 alloy and ZrSiO₄. Also grain size and shape of reinforcement particle determine bonding ability. If the reinforcement does not mix and bond with metal matrix, during tensile test due to the lack of bonding it fails. This has caused reduction of tensile strength in the above composite specimen.
<figure><img src="image_7.png" /><figcaption>Fig. 2, (a) SEM image after tensile test.</figcaption></figure>

<figure><img src="image_8.png" /><figcaption>Fig. 2, (b) SEM image after tensile test.</figcaption></figure>

Wear Analysis

The type of wear testing set up used to carry out experiment is a pin-on-disc Ducom Linear Reciprocating Tribometer. Wear test was conducted at a load of 50N. The distance travelled by mild steel pin on the specimen was 720m. The temperature range was from 35C to 44C with a frequency of 10Hz. No lubricant was used as test is carried out in dry conditions. Care has been taken that the specimen under test was continuously cleaned with woolen cloth to avoid the entrapment of debris for accurate results.

Table 4 shows the values obtained during wear test. The frictional force value is 32.189N and Coefficient of friction is directly proportional to frictional force and its value is of is 0.635. The values clearly prove the high wear resistant property of composite specimen. It is evident that wear resistance behaviour of composite increased due to the addition ZrSiO₄ in the metal matrix.
<table><caption>Table 4. Shows wear test results.</caption><thead><tr><td>COF</td><td>FF(N)</td><td>TEMP (°C)</td><td>LOAD (N)</td><td>SPEED</td><td>WEAR (μm)</td></tr></thead><tbody><tr><td>0.635</td><td>32.189</td><td>34.622</td><td>50.704</td><td>608.964</td><td>104.206</td></tr></tbody></table>

**Summary.** Composite specimen was successfully designed and fabricated using stir casting bottom pouring technique. Microstructure analysis proves the existence and distribution of ZrSiO₄ in the metal matrix. Hardness test proves improvement of hardness value up to 40% due to the good cohesion between metal matrix and reinforcement phase. Tensile test result proves elevation in mechanical property and it is minimum level due to the agglomeration of reinforcement particles and poor boning. Optical micro graphs strengthen this fact. Wear resistant property which is one of the peculiar properties of Composite has been achieved due to reinforcement of ZrSiO₄ in metal matrix Al 6061. The wear is measured in microns and its value is 104.206μm. Altogether above fabrication and tests concludes successful fabrication of aluminium metal matrix composite with elevated metallurgical mechanical and tribological property.

References

[1] Alaneme, K. K., & Bodunrin, M. O. (2013). Mechanical behaviour of alumina reinforced AA 6063 metal matrix composites developed by two step-stir casting process. Acta Technica Corviniensis-bulletin of engineering, 6(3), 105.

[2] Sreenivasan, A., Paul Vizhian, S., Shivakumar, N. D., Muniraju, M., & Raguraman, M. (2011). A study of microstructure and wear behaviour of TiB₂/Al metal matrix composites. Latin American Journal of Solids and Structures, 8(1), 1-8.

[3] Skolianos, Stefanos. "Mechanical behavior of cast SiC p-reinforced Al-4.5% Cu-1.5% Mg alloy." Materials Science and Engineering: A 210.1 (1996): 76-82.

[4] Singh, D., Singh, H., Kumar, S., & Singh, G. (2012). An Experimental investigation of Mechanical behavior of Aluminum by adding SiC and Alumina. International Journal on Emerging Technologies, 178-184.

[5] Liang, Y. H., Wang, H. Y., Yang, Y. F., Wang, Y. Y., & Jiang, Q. C. (2008). Evolution process of the synthesis of TiC in the Cu-Ti-C system. Journal of Alloys and Compounds, 452(2), 298-303.

[6] Min, S. O. N. G. (2009). Effects of volume fraction of SiC particles on mechanical properties of SiC/Al composites. Transactions of Nonferrous Metals Society of China, 19(6), 1400-1404.

[7] Prabu, S. B., Karunamoorthy, L., Kathiresan, S., & Mohan, B. (2006). Influence of stirring speed and stirring time on distribution of particles in cast metal matrix composite. Journal of Materials Processing Technology, 171(2), 268-273.

[8] Aruri, D., Adepu, K., Adepu, K., & Bazavada, K. (2013). Wear and mechanical properties of 6061-T6 aluminum alloy surface hybrid composites [(SiC+ Gr) and (SiC+ Al 2 O 3)] fabricated by friction stir processing. Journal of Materials Research and Technology, 2(4), 362-369.

Cite the paper

S. JohnyJames, A. Raja Annamalai (2017). Fabrication of Aluminium Metal Matrix Composite and Testing of Its Property. Mechanics, Materials Science & Engineering, Vol 9. Doi 10.2412/mmse.62.86.695