Effect of Mg on the Sintering of Al-Mg Alloy Powders by Pulse Electric-Current Sintering Process

Abstract

Utilization of deoxidization mechanism of magnesium (Mg) is an effective method to remove the oxide films at aluminum (Al) alloy powder surface in pulse electric-current sintering (PECS) process. The continuous amorphous oxide film at Al alloy surface are broken and removed by deoxidization of Mg. Crystalline particles of MgAl 2 O 4 or MgO, or both of them, are formed, which depend on Mg content in Al alloy powder and sintering temperature. After that the metal/metal contact is caused, and solid state sintering of Al alloy powder is facilitated. The electrical resistivity and tensile properties of powder compacts are improved by Mg addition. Based on the analyses of electrical resistivity, tensile properties and microstructures of the sintered specimens, optimum amount of Mg addition to improve the sintering properties of Al powder is determined to be 0.3-2.5 mass%.

Ceramic Particulate Reinforced Zr<SUB>55</SUB>Cu<SUB>30</SUB>Al<SUB>10</SUB>Ni<SUB>5</SUB> Metallic Glassy Matrix Composite Fabricated by Spark Plasma Sintering

“…Thus the temperature at the contact interfaces between powder particles should be higher than the average temperature for the sintered specimens due to the focused current and Joule heat at the bonded interface between powder particles, which has been demonstrated in our previous investigations of AlMg alloy powders sintered by the SPS process. [14][15][16] This local high temperature can enhance the formation and growth of the neck between powder particles, and improve the properties of the sintered BMG specimens. On the other hand, Tokita 12) indicated that the application of the pulse voltage in the SPS process enhanced thermal diffusion.…”

Densification of Gas Atomized Ni-Based Metallic Glassy Powders by Spark Plasma Sintering

“…Thus the temperature at the contact interfaces between powder particles, especially at low relative density, should be higher than the average temperature for the sintered specimens due to the focused current and Joule heat at the bonded interface between powder particles, 14,15) which has been demonstrated in our previous investigations of Al-Mg alloy powders sintered by the SPS process. 16,17,27) This local high temperature can enhance the formation and growth of the neck between powder particles, and improve the properties of the sintered specimens. The sintering temperature is measured and controlled by a thermocouple inserted into the die wall with a distance of about 5 mm from the sintered powders in the present study.…”

Fabrication of ZrCuAlNi Metallic Glassy Matrix Composite Containing ZrO<SUB>2</SUB> Particles by Spark Plasma Sintering Process

“…Thus the temperature at the contact interfaces between powder particles, especially at low relative density, should be higher than the average temperature for the sintered specimens due to the focused current and Joule heat at the bonded interface between powder particles, 14,18) which has been demonstrated in our previous investigations of Al-Mg alloy powders sintered by the SPS process. [19][20][21] This local high temperature can enhance the formation and growth of the neck between powder particles, and improve the properties of the sintered BMG specimens. With increasing relative density, the contact area between powder particles increases, a relative homogeneous temperature field is created.…”