Because of higher relative strength and stiffness than Fe alloys, aluminum alloys are very attractive materials for aerospace, aircraft, and automobile industries [1-4]. The metal matrix composites reinforced with discontinuous reinforcement‘s particles are attractive for applications needs higher thermal stiffness and strength than monolithic alloys. Cu-based shape memory particles (Cu-Al-Ni) seem to be a noble candidate for the reinforcement of metal matrix composite known as an adaptive composite. Cu-Al-Ni particles are chemically stable in aluminum alloys and exhibit good mechanical properties at relatively low cost [5]. The shape memory alloy embedded composites have microscopic scale thermal residual stresses, which are generated during cooling from the high-temperature due difference in CTEs and cannot remove by heat treatment [6]. The growth of such stresses and mechanical behavior of MMC in the occurrence of these stresses has been thoroughly studied by several authors [7-11]. The automobile parts and structures experience shape memory effect because of their service temperature. The property of adaptive composites varies by a change in the residual stress field due to SME. The current investigation presents the relation between CTE and residual stresses are investigated for varying volume fractions of reinforcement particles.

A. Composite preparation The matrix material used for producing an adaptive composite in this study is aluminum 2024. This alloy is best suited for mass production of lightweight castings. Table 1 indicates the chemical composition of Al 2024 alloys Table 2 shows the mechanical properties of the Cu-Al-Ni shape memory particulates and the Cu-Al-Ni of 100 µm is reinforced in the matrix material. The reinforcement volume fractions 5%, 10%, and 15% are introduced by liquid route technique known as stir casting.

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Using stir casting technique the reinforcement material is poured into the molten metal pool during the vortex formed by alumina glazed stainless steel stirrer, alumina glazing to blades of the stirrer is essential to prevent the movement of ferrous ions from the stirrer into the molten metal. The rotation of the stirrer is 0-750 rpm and the depth of immersion is two third depth of the molten alloy. The molten alloy is degassed by pure nitrogen for about 3 to 4 minutes and the mixture is poured into the preheated metallic molds. B. Specimen preparation: The diffraction test specimens were prepared from the cylindrical casting of Al 2024 in accordance with the ASTM standard by machining. The diameter and height of the specimen are 10 mm and 05 mm. The polishing of specimen surfaces was made by 1 µm diamond paste. The results are taken by considering four specimen samples under identical conditions and etched by Keller‘s reagent [12-13]. At last washed with distilled water followed by acetone and dried. C. Cu-Al-Ni particles shape memory effect in Al 2024 alloy: The relation between reinforcement particles and matrix Al 2024 is critical because the application needs a transfer of load and strain from the particles to the matrix. The matrix has a pronounced effect on local stress state and transformation behavior particles. This work is based on the research of Jonnalagadda et al. D. CTE measurement: Coefficients of thermal expansion tests were carried out with Thermomechanical analyzer TMA Q400 shown in figure 1. The specimens were subjected to a constant load of 0.5 N and readings were taken from temperature 30 °C to 500 °C for the heating part of the cycle and from 500 °C to 30 °C for cooling part of the cycle at a sweep rate of 5 °C. E. Residual stress measurement: Residual stress measurement is carried out by BRUKER D8 ADVANCE X-ray Diffractometer with specification horizontal/vertical θ/2θ or θ/θ geometry as shown in figure 1, circle diameter 435, 500, and 600 mm. Maximum usable angular Range 110° ˂ 2θ ≤ 168°, the smallest adjustable increment of 0.0001°, anodes of Cu, Cr, and Co and application software of EVA LEPTOS & TOPAS.

Figure 3 indicates that the composites obtained from stir-casting methods are good quality and sound castings. Figure 4 shows the variation of CTE measured from TMA Q400. In this, for the as-cast composites, CTE decreases as the particulate volume fraction increases due o the difference in expansion values of reinforcement and host matrix. Further, for the SME composites CTE increases as the particulate volume fraction increases due to shape memory

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and host matrix. Figure 5 shows the variation of residual stress measured from high-resolution XRD machine, in this for as-cast composites residual stress decreases as the particulate volume fraction increases due to plastic flow. Further for SME composites residual stress increases as the particulate volume fraction increases due to shape memory effect and plastic flow simultaneously.

Thermal expansion and residual stress is a function of particulate volume fraction and the variation will be in a pronounced effect when the composites were subjected to shape memory effect.

conclusions can be drawn, the variation of both coefficient of thermal

Authors would like to thank, the Secretary, VGST, Department of Information Technology, Biotechnology and Science &Technology, Government of Karnataka for project fund of Rs.10 Lakhs /year for two years (Ref No. K- FIST (Level-1), Proposal No. L1-7 of 2012-13).

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Research Student, Visvesvaraya Technological University, Research Resource Center, Belagavi, Karnataka, Belagavi, Karnataka, India