International Journal of Engineering Research ISSN:2319-6890)(online),2347-5013(print) Volume No.4, Issue No.9, pp : 470-474 01 Sept. 2015 IJER@2015 Page 470 Microstructure and Wear Behavior Of as Cast Al-25mg2si-2cu-2ni Alloy 1 Geetanjali.S.Guggari , 2 Veena.Badiger , 3 Dr. Shivakumar S Department of Industrial and Production Engineering ,KLS Gogte Institute of Technology, Belagavi, Karnataka, India 1 gsguggari@git.edu 2 vbadiger@git.edu 3 sshivakumar@git.edu Abstract: The remarkable feature of the Aluminium is its low density and ability to withstand corrosion effect due to phenomenon of passivation. Structural components made from Aluminium and its alloys are vital to the aerospace industry and are important in other areas of transportation and structural materials. The oxides and sulphate are useful compounds of Aluminium based on its weight. In this work, an attempt has been made to utilize the combined effect of high cooling rate solidification, unique micro structural evolution mechanism of T6 heat treatment the advantages of hypereutectic Al-Si system alloyed with other elements such as Cu, Fe and Mg. In the present investigation, the binary alloys in the hypereutectic range viz. Al25Mg2Si has been selected as heat resistant Al-Si alloys. A systematic approach has been carried out to explore the micro structural features, mechanical and wear properties of as cast alloys. Keywords – Aluminium, Passivation, Hyperutectic I. Introduction Aluminium (Al) has been at the center of various engineering applications since long. Aluminium and its alloys had become economic competitors in engineering applications because of their useful features, which include its lightweight with a density of approximately one third of that of steel, attractive appearance, fabric ability and excellent corrosion resistance, re- cycle ability, formability and conductivity. The main driving force for using Al-Si alloys by replacing iron based alloys in the automotive and aerospace industries is improved mechanical properties, lower production cost and greater strength to weight ratio which has also met the demand for reduced pollution and increased performance. [1] Alloying elements are selected based on their effect and Suitability. Silicon lowers the melting point and increase the fluidity (improve casting characteristics) of Aluminium. A moderate increase in strength is also provided by Silicon addition. Different alloying elements added to Al-Si alloy will improve its tribological properties. Some composites of Al-Si alloys are also improve its wear rates and friction properties. [2] Al2Cu and Al-Si-Cu-Mg phases are relatively stable below 150°C and Mg2Si phase will coarsen over 180°C giving rise to a sharp decrease in high temperature strength. [3] The microstructure of spray formed and hot pressed alloy consists of fine and uniform distribution of both primary and eutectic Si with fine needles of Q-Al12Si7Mg4Fe intermetallics and Chinese script like θ-Al2Cu precipitates in the Al matrix. Hot pressing has reduced the porosity from 10 to 1 % in spray formed alloy. The objectives of the present study is to utilize the combined effects of high cooling rate solidification, unique micro structural evolution mechanism of T6 heat treatment and the advantages of hypereutectic Al-Si system alloyed with other elements such as Cu, Fe and Mg. In the present investigation, the binary alloys in the hypereutectic range viz. Al25Mg 2 Si has been selected as heat resistant Al-Si alloys. A systematic approach has been carried out to explore the micro structural features, mechanical and wear properties of as cast alloys. II. Material and Methodology A. Material selection In the present investigation, the binary alloys in the hypereutectic have been Al-25Mg 2 Si-2Cu-4Fe-4Ni alloy is used to represent the light weight heat treatable Al-Mg 2 Si-Cu alloys. Table 1 summarizes the nominal compositions of all the selected alloys. The chemical composition of all the alloys is anlalysed by spark emission spectrometer. Table.1 Chemical Composition of (wt %) Al25Mg 2 Si-2Cu-2Fe- 2Ni alloy Alloy %Si % Fe % Cu % Mg %N i %Al Al- 25Mg 2 Si- 2Cu-2Fe- 2Ni 11 1.86 2 14 1.9 6 Bala nce B. Wear test Dry sliding wear test The wear test is carried out using a pin-on-disc type wear- testing machine .The samples are cleaned prior to and after each interval of wear test with acetone. The wear rates of the alloys found out by measuring the difference in weight of the specimens measured before and after the tests (measured with an analytical balance Mettler AJ100, Hightstown, NJ of 0.1 mg precision). Wear specimen of size 30 mm length and 10 mm diameter are machined from differently processed samples. The contact surface of the specimen are polished up to 1200 mm grit size and tested against a rotating EN-32 steel wear disc with a hardness value of HRC 65. The wear tests are carried out at sliding velocities for a fixed sliding distance of 2000 m at different normal loads. The frictional force induced on the specimen is recorded constantly during the wear test by a load