Hot Extrusion Treatment Research Articles

Effect of Hot Extrusion on Microstructure, Texture, and Mechanical Properties of Mg-Zn-Mn-0.5Ca Alloy

This paper investigates the microstructure, texture, and mechanical properties of the Mg-4Zn-1Mn-0.5Ca alloy subjected to hot extrusion under varying conditions of temperature (260 °C, 300 °C, 340 °C) and extrusion speed (0.01 mm/s, 0.1 mm/s, 1 mm/s). The primary objective is to determine the optimal extrusion parameters within the selected experimental range for achieving superior mechanical properties. The results indicate that, when extruded at a constant speed of 0.1 mm/s, the alloy exhibits optimal performance at 340 °C, with a yield strength of 202 MPa, ultimate tensile strength (UTS) of 306 MPa, and elongation at fracture of 18.9%. A decrease in extrusion temperature leads to an increase in yield strength but a reduction in ductility. Specifically, the UTS reaches its peak at 342 MPa at 300 °C, while it drops slightly to 329 MPa at 260 °C. The final results show that the comprehensive mechanical properties of the Mg-4Zn-1Mn-0.5Ca alloy obtained by hot extrusion treatment with an extrusion temperature of 300 °C and extrusion speed of 0.1 mm/s are the best and can effectively improve the mechanical properties of the alloy and provide a good choice for the preparation of other biodegradable magnesium alloy products.

Exploring the relationship between nutritional properties and structure of chestnut resistant starch constructed by extrusion with starch-proanthocyanidins interactions

Driven by the high economic value of chestnut, creating chestnut-based food with nutritional functions has become a hot spot in food industry. In this study, effect of hot-extrusion treatment (HEX) with starch-proanthocyanidins (PR) interactions (HEX-PR) on chestnut starch (CS) nutritional properties was evaluated from the perspective of structural changes. Results showed that HEX-PR promoted the formation of ordered structure of CS containing single helix, V-type crystalline structure, and starch aggregates, thus increasing the resistant starch (RS) content from 3.25 % to 12.35 %. For the nutritional evaluation, the α-amylase inhibitory activity, antioxidant activity and antiglycation activity of HEX-PR treated CS (HEX-PRS) were enhanced, and the enhancing effect became stronger as PR concentration rose. In addition, HEX-PRS increased the level of short-chain fatty acids (SCFAs), especially propionate, and meanwhile enriched beneficial intestinal bacteria especially the Bifidobacterium. Notably, correction analysis showed that the microbial community was closely related to the α-amylase inhibitory activity, antioxidant activity and antiglycation activity. Overall, this study provided an approach for improving the nutritional functions of starch, and could offer guidance for further investigations to improve the nutritional quality of chestnut starch-based foods.

Processing and Mechanical Properties of Ti2AlC MAX Phase Reinforced AE44 Magnesium Composite

AE44 alloys and nanolaminated Ti2AlC particle-reinforced AE44 magnesium composites were synthesized by stir casting techniques and textured by hot extrusion methods. It was found that lamellar Al11RE3 precipitates spheroidized with the introduction of Ti2AlC into the AE44 matrix. Both transmission electron microscope and planar disregistries calculations reveal a good match for interfacial lattice transition between Mg (0001) and the basal plane (0001) of Ti2AlC. This suggests that Ti2AlC is an efficient potent nucleating substrate for Mg, thus fertilizing the formation of strong interfacial bonds. After hot extrusion treatment, Ti2AlC particles were reoriented in the textured magnesium matrix, as confirmed by X-ray diffraction. This texture effect on the composite’s mechanical properties was carefully studied by tensile and compressive tests.

Effect of heat treatment on the mechanical and tribological properties of AA8090/6% SiCp composite

Abstract AA8090, a certain type of Al-Li alloy, has been widely used in the aerospace industry because of its low density and high strength after heat treatment. In this research work, the AA8090/6% SiCp composite was produced by modified stir casting and then subjected to hot extrusion treatment. One part of the extruded rod was used to prepare the wear test samples and the remaining part was converted to strips with 2 mm thickness via hot rolling process. Three processes, including precipitation hardening with conventional heating, age hardening with rapid heating, and precipitation after directional quenching, were done on samples. The results of the mechanical properties revealed that precipitation hardening after directional quenching reduced the peak of hardness time from 16 to 6 h, increased the peak of hardness by 20%, and improved the tensile strength, yield stress, and elongation by 16%, 16%, and 40%, respectively. The results of wear test indicated that, at the load of 10 N, abrasive wear was the dominant wear mechanism. Increase in load showed delamination, and at the load of 30 N, a transition from mild wear to severe wear occurred due to a change in wear mechanism to adhesive wear. At this load, the samples without heat treatment showed the lowest wear rate in comparison to the samples subjected to heat treatment. By and large, the specimens heat treated with directional quenching among the other heat-treated specimens showed the higher wear resistance at all of loads.

Effect of Sr content on microstructure and mechanical properties of Mg-Li-Al-Mn alloy

The as-cast Mg-8Li-3Al-0.5Mn-xSr (LAM830-xSr, x=0-1.0) alloys were designed and prepared in a vacuum induction furnace under controlled argon atmosphere. The alloys were then processed by hot extrusion, and their microstructural evolution and mechanical properties were analyzed. Results indicate that the LAM830 alloy mainly consists of α-Mg, β-Li, Al2Mn3, and LiMgAl2 phases. Sr addition results in the precipitation of Al-Sr. Moreover, Sr addition results in a fact that the secondary dendrite arm spacing (DAS) of the primary a-Mg phase is obvious refined. Microstructure of the investigated alloys is further refined as a result of the hot extrusion treatment. The content and morphology of the secondary phases have important effects on the mechanical properties of the alloys. The as-extruded LAM830-0.5Sr alloy exhibits an optimal elongation of 22.43% and as-extruded LAM830-0.75Sr alloy shows an optimal tensile strength of 265.46 MPa.

Microstructure and properties of hot extruded AZ31-0.25%Sb Mg-alloy

The effects of hot extrusion treatment on the microstructure and mechanical properties of AZ31-0.25%Sb Mg alloy were investigated by means of mechanical properties measurement and microstructure observation. The results show that the microstructure of AZ31-0.25%Sb Mg alloys consists of α-Mg matrix, Mg 17Al 12 and Mg 3Sb 2 phases. The ultimate tensile strength (UTS) and yield tensile strength(YTS) of the alloy are obviously enhanced by hot extrusion treatment, and the enhanced extent of UTS and YTS increases with the decrease of hot extrusion temperature, moreover, the YTS value of the alloy at RT, after extruded at 220 °C, increases up to 131.4%, which attributes to the finer grains resulted from the dynamic recrystallization occurred during hot extrusion. As hot extrusion goes on, the slipping and concentration of dislocations continue to occur within the finer grains, which promotes the formation of the subgrains in the alloy. The deformation features of the extruded alloy during tensile deformation at RT are the twinning deformation and dislocation slipping in the twinning regions. Moreover, the deformation mechanisms of the alloy are a dislocation activation on the basal plane and a+c dislocation activation on the pyramidal planes.

Anisotropy in extruded lanthanum borogermanate glasses? Structural study by Raman spectroscopy

Polarized Raman spectra of lanthanum borogermanate (LBG) glasses of different compositions, as well as of LBG glasses obtained by the hot-extrusion technique, have been obtained. In addition, the crystallization behaviour of LBG glasses of different compositions has been studied by differential thermal analysis and X-ray diffraction. Both the Raman spectra profile and the crystallization behaviour depend on the lanthanum–boron ratio. Polarized Raman spectra of hot-extruded samples show differences from the unextruded samples. For the first time, structural changes in glasses under hot-extrusion treatment were observed by vibrational spectroscopy.