Gazi Üniversitesi Fen Bilimleri Dergisi (Sep 2020)
The Effect of B4C Reinforcement Ratio and Secondary Sintering Processes on Properties of Al6061 Matrix MMCP Materials
Abstract
In this experimental study, the effect of reinforcement ratio and liquid phase sintering on properties of Al6061 matrix B4C particle reinforced Metal Matrix Composite (MMCP) materials produced by hot pressing active sintering method was investigated. Pre-alloyed Al6061 metal powder with 0%, 5%, 10% and 15% (wt) B4C ceramic particle reinforcing elements were mixed in the turbula device for 45 minutes. The mixture powder was compressed in the mold in dimensions 40x60mm2 at a pre-pressing pressure of 200 MPa at room temperature. Subsequently, lubricant removal process was applied for 45 minutes at 400ºC under argon atmosphere in the same mold block. Then, MMCP materials were produced by applying hot pressing (HP) active sintering under argon atmosphere for 1 hour under pressure of 100 MPa at 550ºC. Secondary sintering was performed on these samples by applying supersolidus liquidphase sintering (SLPS) for 1 hour at 610ºC. Microstructures and physical properties of composite materials produced; characterized by metallographic examination, hardness and density measurements, transverse rapture strength (TRS) test and fracture surface analysis by scanning electron microscopy (SEM). At the end of the SLPS process, the samples were cooled fast in water (W) and slow in the furnace (F), and the effect of the cooling rate was also investigated. SLPS process partially reduced the density of MMCP materials produced by HP. This effect is especially high in furnace cooled samples. However, there was a significant increase in the hardness and TRS values of the samples cooled in water quickly.
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