Effect of Milling Conditions on the Microstructural Design in Aluminum Based Alloy Fabricated by SPS

Abstract

In this work, aluminum-based alloys were mechanically alloyed by various doping elements followed by spark plasma sintering. Three different mixing methods were studied. First, all elemental powders were mixed for 24 h. In the second and the third method, powders were divided into three groups, and each group was milled separately for different times. Then the obtained mixtures were grouped together and again milled for 12 and 24 h, for the M2 and M3 mixtures, respectively. The influence of milling parameters on the microstructural features of sintered samples was determined using a scanning electron microscope (SEM) equipped with an energy-dispersive X-ray spectroscopy system. The correlation observed between the milling time and microstructural evolution of the powder particles during the milling process was to determine the optimal process parameters. For the first time, the present research has demonstrated the effectiveness of the milling process for the preparation of tailored mixtures of metallic powders, enabling microstructural characteristics that could be favorable for the formation of secondary structures on the tribosurfaces.

Enhancement of the Mechanical and Tribological Properties of Aluminum-Based Alloys Fabricated by SPS and Alloyed with Mo and Cr

“…The friction coefficient for Al-Cr composition was two times lower and 12% less than for bronze and Al-Mo, respectively. These results support the conclusions claim that the value of friction coefficients is not a major criterion of materials wear resistance, which was reached in the previous study [48].…”

“…In our previous study, we had confirmed the effectiveness of the MA and spark plasma sintering method for the preparation of tailored mixtures of metallic powders, enabling microstructural characteristics that could be favorable for the formation of secondary structures on the tribosurfaces [48]. However, the evaluation of the mechanical and tribological behavior of the obtained compositions was not presented.…”

“…The resultant mixture was homogenized for 12 h. It should be clarified that hard metal balls were used for homogenization and each mixture was dried, grounded in an agate mortar, and passed through a 63 µm sieve. More detailed information concerning the mixing process was provided in the previous study [48]. Obtained suspensions were dried using a vacuum drying oven and sieved through a 63 µm mesh.…”

“…Zinc does not form phases and has a relatively homogeneous distribution with some areas of high concentration related to Cu. More detailed information concerning the microstructure characterization, EDS chemical identification of elements, and their concentration in Al-Mo alloy was provided in the previous study [48]. Figure 5 shows SEM-EDS elemental distribution maps in the Al-Cr alloy.…”

“…This consolidation method offers considerable advantages such as faster and shorter processing time compared to conventional sintering methods, due to simultaneous application of mechanical pressure and electric pulse. The advantages of this technique are associated with a high densification rate and fine microstructure and consequently better properties [46][47][48][49]. Moreover, SPS allows the breaking of the continuity of oxide film on the surface of aluminum particles.…”