Arda ÇETİN
Room: A-201
Lab: A-101
(+90)312 210 5950 (room)
(+90)312 210 5907 (lab)
E-mail: acetin@metu.edu.tr
Courses/Labs:
Principles of Solidification, Casting and Solidification Lab.
Interests:
Solidification Processing, Thermal Analysis, Quantitative Metallography
Former Degree: B.S., M.S.; Metallurgical and Materials Engineering Dept, METU
Current Degree: Ph.D.; Metallurgical and Materials Engineering Dept, METU
Thermal Analysis of SiCp Reinforced A356 Alloy Matrix Composite
Supervisor: Dr. Ali KALKANLI
The aim of the present study is to adapt the Newtonian and Fourier theory based thermal analysis procedures to solidification of SiCp reinforced A356 alloy matrix composite to obtain information about the solidification process of the composite as well as the particulate distribution. A computer program is written to process the thermal data obtained during solidification in order to calculate the latent heat of fusion, dendrite coherency points (DCP), transformation temperatures, and evolution of fraction solid. The particulate distribution was characterized by radial distribution function (RDF). It was observed that the fraction solid at dendrite coherencies may be a useful index to monitor the particulate distribution since the Al-dendrites always nucleate in the liquid away from the particles and push them into interdendritic spaces resulting in micro or macro-segregation depending on solidification conditions. The Newtonian procedure with variable thermophysical properties and the Fourier procedure are successfully adapted to composite solidification and a numerical solution to the problem by finite difference method (FDM) is also presented.
The cooling curve, its derivative and the derivative of the zero curve presented with the evolution of fraction solid for A356 alloy reinforced with 10 vol% SiCp. The cooling rate is 0.278 C/s. The transformation temperatures are calculated as; liquidus temperature = 614.1 C, eutectic nucleation temperature = 565.2 C and the end temperature of transformation = 544.0 C. The latent heat of fusion is calculated as 368.08 kJ/kg for that particular composite and the solid fraction at the dendrite coherency is 0.087.
mp
mc
The quantitative characterization of the spatial distribution of the SiC particulates is carried out with (a) the radial distribution function (RDF) and (b) the agglomeration index, which is defined as the ratio of loose particles to agglomerates. A typical RDF curve for a composite is given in (c). It was seen that the area under the RDF curve may be regarded as an index to the deviation from homogenity and may be used to monitor the particle distribution when considered with the agglomeration index.