Properties Evolution during Transient Liquid Phase Sintering of PM Alumix 431

This paper reports a study on densification and microstructural changes, which were occurred during transient liquid phase sintering of Alumix 431. The objective was to find the optimum sintering temperature for obtaining higher densities and improved mechanical properties. For this purpose, the commercial Al powder mixture ECKA Alumix 431 was pressed at 400 MPa and sintered under pure nitrogen in a broad range of temperature between 580 and 620◦C for 30 minutes in N2. The effect of sintering temperature was evaluated by measuring sintered density, transverse rupture strength, dynamic Young’s modulus, and macrohardness. The optical microscopy and scanning electron microscopy used for studying microstructural characterization and fracture surface of the resulting materials, respectively. It could be observed that the sintered density increases with higher sintering temperature up to a certain limit, rearrangement as well as pore elimination due to transient liquid phase sintering being helpful. On the other hand, too high sintering temperatures are unwelcome either apparently as a consequence of Zn evaporation and microstructural change such as grain growth. It was found that the maximum sintered density for Alumix 431 is attained by sintering at the range of 610◦C when the amount of liquid phase is satisfactory.