Grain growth kinetics of bulk AZ31 magnesium alloy by hot pressing

Characterization of Powder Metallurgy Processed Pure Magnesium Materials for Biomedical Applications

“…Increasing the compaction pressure (above 300 MPa) at RT had an influence on the deformation of the powder particles while increased deformability of particles corresponded with increasing compaction pressure. The influence was also sufficient for changing the character of the porosity from open porosity to closed porosity and decreased the number of pores on the samples' cross-sections, which is in agreement with [11][12][13]. Hot pressing led to a significant decrease of the porosity of the compacts and also to a change in the character of the porosity (Figure 2) [4,32].…”

“…Improvement of mechanical properties by hot pressing of pure magnesium is visible in Figures 3 and 4. Hot pressed samples prepared at 300 • C revealed the same trend in increasing flexural strength with increasing compaction pressure as samples prepared at 400 • C; however, the values of flexural strength are slightly higher for the series of samples prepared at 400 • C. This fact can be attributed to a higher diffusion rate of magnesium at 400 • C, which leads to better diffusion bonding between powder particles and possibly more pronounced grain coarsening at higher temperature [11]. Samples prepared at 500 • C reached much lower values of flexural strength compared to other hot pressed samples (comparing samples prepared under the same pressures) and only slightly higher than cold compacted samples (Figure 4a).…”

“…Powder particles' deformation leads to cracking of the layer of corrosion products normally present on the powder particles' surface [11][12][13]. The applied plastic deformation results in an increase of the contact area of powder particles and, in combination with the applied temperature, enhances the diffusion processes.…”

“…The applied plastic deformation results in an increase of the contact area of powder particles and, in combination with the applied temperature, enhances the diffusion processes. Increasing compacting pressures usually also lead to a decrease in the porosity of the processed bulk material [11][12][13]. The porosity of the processed bulk material is usually considered as a disadvantage of the PM processing techniques.…”

Effect of ball milling time on nanocrystalline powders and bulk ultrafine-grained Mg-3Al-Zn alloy

“…However, the symmetry of the hexagonal close-packed crystal structure results in poor formability and ductility near room temperature [2]. According to Hall-Petch relationship, grain refinement is one of the most effective methods to improve the strength of the material, the resulting ultrafine-grained (UFG) structure can bring about high strength and even superplasticity at high strain rates and low temperatures [3][4][5]. Of the many techniques used for achieving UFG microstructures, such as equal channel angular extrusion (ECAE) [6], friction stir processing(FSP) [7], accumulative roll bonding (ARB) [8], high-pressure torsion (HPT) [9] and powder metallurgy (PM) [10], PM was an effective technique to synthesize high strength UFG Mg alloys [11][12][13][14][15].…”