Influence of Micron-Ti and Nano-Cu Additions on the Microstructure and Mechanical Properties of Pure Magnesium (original) (raw)
Related papers
2012
In this study, the effects of the addition of individual micro-and nano-sized metallic elements (micron-Ti and nano-Cu) and their combination on the microstructure and mechanical properties of pure Mg were investigated. The materials were produced by rapid microwave sintering assisted powder metallurgy technique followed by hot extrusion. From the microstructural characterization and mechanical property evaluation, it was identified that the solid solubility, size and the method of addition of elements significantly influenced the properties. While the insoluble micron-Ti enhanced the strength and reduced the ductility due to weak interface, the addition of nano-Cu with relative solid solubility enhanced the strength due to the formation of Mg 2 Cu intermetallics and retained the ductility. The positive effect of their combined addition was found to be more pronounced when they were pre-processed, rather than their direct addition. The change in particle morphology, Ti 3 Cu intermetallic formation and good interfacial bonding with the matrix achieved due to pre-processing contributed towards its superior strength and ductility.
Metals, 2018
The present study reports the development of new magnesium composites containing complex composition alloy (CCA) particles. Materials were synthesized using a powder metallurgy route incorporating hybrid microwave sintering and hot extrusion. The presence and variation in the amount of ball-milled CCA particles (2.5 wt %, 5 wt %, and 7.5 wt %) in a magnesium matrix and their effect on the microstructure and mechanical properties of Mg-CCA composites were investigated. The use of CCA particle reinforcement effectively led to a significant matrix grain refinement. Uniformly distributed CCA particles were observed in the microstructure of the composites. The refined microstructure coupled with the intrinsically high hardness of CCA particles (406 HV) contributed to the superior mechanical properties of the Mg-CCA composites. A microhardness of 80 HV was achieved in a Mg-7.5HEA (high entropy alloy) composite, which is 1.7 times higher than that of pure Mg. A significant improvement in compressive yield strength (63%) and ultimate compressive strength (79%) in the Mg-7.5CCA composite was achieved when compared to that of pure Mg while maintaining the same ductility level. When compared to ball-milled amorphous particle-reinforced and ceramic-particle-reinforced Mg composites, higher yield and compressive strengths in Mg-CCA composites were achieved at a similar ductility level.
In the current study, the role of nano-Al 2 O 3 addition to Mg-5.6Ti-3Al composite and subsequent recrystallisation heat treatment in improving the mechanical properties are investigated. The following Mg composites: (i) Mg-5.6Ti-3Al (with 3 wt% Al and 5.6 wt% Ti) and (ii) Mg-5.6Ti-3Al-2.5Al 2 O 3 (with 3 wt% Al, 5.6 wt% Ti and 2.5 wt% Al 2 O 3) were synthesised through the disintegrated melt deposition (DMD) technique followed by hot extrusion. Mg-5.6Ti-3Al-2.5Al 2 O 3 composite was then subjected to recrystallisation heat treatment at 200ºC for 5 h. Mechanical property evaluation of the developed Mg composites indicated a significant improvement in microhardness and tensile properties when compared to pure Mg and Mg-5.6Ti-3Al. Microstructural characterisation revealed a significant grain refinement and uniform distribution of reinforcements/second phases in the developed Mg composites due to hybrid reinforcement additions and heat treatment. In case of as-extruded Mg-5.6Ti-3Al-2.5Al 2 O 3 composite, the strength improvement occurred at the expense of ductility while for heat-treated composite, the increase in strength properties was accompanied by an increase in ductility. Based on the processing-structure-property correlation, it was identified that the presence of hard reinforcements/intermetallics in Mg matrix contributes to the improvement in strength properties while the stress relaxation during heat treatment contribute to the ductility enhancement.
Improved mechanical proprieties of “magnesium based composites” with titanium–aluminum hybrids
Journal of Magnesium and Alloys, 2015
In this study, the effect of micron-sized titanium and aluminum addition on the microstructural, mechanical and work-hardening behavior of pure Mg is investigated. Pure Mg reinforced with 10%Ti and 10%Tie1%Al particulates were synthesized through semi-powder metallurgy route followed by hot extrusion. Semi-powder metallurgy appears to be promising approach for the synthesis of Mg based composite, as it is free of ball milling. Tensile results indicate that the direct addition of micron-sized 10wt.% titanium particulates to pure Mg, caused an improvement in elastic modulus, 0.2% yield strength, ultimate tensile strength, and failure strain (þ72%; þ41%; þ29%; and þ79% respectively). The addition of micron-sized 10wt.% titanium particles along with 1.0wt.% Al particles to pure Mg, resulted in an enhancement in elastic modulus, 0.2% yield strength, ultimate tensile strength, and failure strain (þ74%; þ56%; þ45%; and þ241% respectively). Besides tensile test, Vickers hardness and work-hardening behavior of prepared composites were also examined. Impressive failure strain of Mge10Tie1Al composite can be attributed to the better compatibility of Ti particulates with Mg due to presence of alloying element Al.
In the present study, a new magnesium based multicomponent alloy consisting of five alloying elements was synthesized using the technique of Disintegrated Melt Deposition (DMD). Most of the conventional Mg based alloys have one dominant principle element with a small amount of other alloying elements. In this work, the alloy having a chemical composition of Mg 70 Al 18 Zn 6 Ca 4 Y 2 (atomic pct.) was designed by incorporating multiple alloying elements (Al, Zn, Ca and Y) with high amount of alloying element concentration (2 to 18 atomic pct.) into principle element, Mg. Investigations were done on the microstructure and mechanical properties of the developed alloy. The formation and presence of phases and microstruc-tural evolution of the alloy were examined using scanning electron microscopy, energy dispersive x-ray (EDX) analysis and x-ray diffraction (XRD) analysis. The mechanical properties of the developed alloy was determined by way of hardness tests and compression testing. Significantly high macrohardness (59 HRB) and microhardness (150 HV) was realized in Mg 70 Al 18 Zn 6 Ca 4 Y 2 multicomponent alloy. The measured hardness values in this alloy was much higher when compared to those of commercial Mg alloys.
In this study, composites containing pure magnesium and hybrid reinforcements (5.6 wt.% titanium (Ti) particulates and 2.5 wt.% nanoscale alumina (n-Al2O3) particles) were synthesized using the disintegrated melt deposition technique followed by hot extrusion. The hybrid reinforcement addition into the Mg matrix was carried out in two ways: (i) by direct addition of the reinforcements into the Mg–matrix, Mg–(5.6Ti + 2.5n-Al2O3) and (ii) by pre-synthesizing the composite reinforcement by ball milling and its subsequent addition into the Mg–matrix, Mg–(5.6Ti + 2.5n-Al2O3)BM. Microstructural characterization revealed significant grain refinement due to reinforcement addition. The evaluation of mechanical properties indicated a significant improvement in microhardness, tensile and compressive properties of the composites when compared to monolithic magnesium. For the Mg–(5.6Ti + 2.5n-Al2O3) composite, wherein the reinforcements were directly added into the matrix, the improvement in strength properties occurred at the expense of ductility. For the Mg–(5.6Ti + 2.5n-Al2O3)BM composites with pre-synthesized ball-milled reinforcements, the increase in strength properties was accompanied by an increase/retention of ductility. The observed difference in behaviour of the composites is primarily attributed to the morphology and distribution of the reinforcements obtained due to the ball-milling process, thereby resulting in composites with enhanced toughness.► Pure Mg with hybrid reinforcements (5.6Ti + n-2.5Al2O3) has been successfully produced. ► Comparative study of direct and ball-milled reinforcement additions was conducted. ► Ball-milling modifies the morphology and distribution of hybrid reinforcements. ► Composites with direct addition show high strength, but low ductility in both tensile and compressive loading. ► Composites with ball-milled reinforcements show improved tensile and compressive strength and tensile ductility.
A Review on Mechanical Properties of Magnesium Based Nano Composites
AIP Conference Proceedings, 2018
A review was done on Magnesium (Mg) based composite materials reinforced with different nano particles such as TiO2, Cu, Y2O3, SiC, ZrO2 and Al2O3. TiO2 and Al2O3 nanoparticles were synthesised by melt deposition process. Cu, Y2O3, SiC and ZrO2 nanoparticles were synthesised by powder metallurgy process. Composite microstructural characteristics shows that the nano-size reinforcements are uniformly distributed in the composite matrix and also minimum porosity with solid interfacial integrity. The mechanical properties showed yield strength improvement by 0.2 percentage and Ultimate tensile strength (UTS) was also improved for all the nano-particles. But UTS was adversely affected with TiO2 reinforcement while ductility was increased. With Cu reinforcement elastic modulus, hardness and fracture resistance increased and improved the coefficient of thermal expansion (CTE) of Mg based matrix. By Y2O3 reinforcement hardness, fracture resistance was improved and ductility reached maximum by 0.22 volume percentage of Y2O3 and decreased with succeeding increase in Y2O3 reinforcement. The readings exposed that mechanical properties were gathered from the composite comprising 2.0 weight percentage of Y2O3. Ductility and fracture resistance increased with ZrO2 reinforcement in Mg matrix. Using Al2O3 as reinforcement in Mg composite matrix hardness, elastic modulus and ductility was increased but porosity reduced with well interfacial integrity. Dissipation of energy in the form of damping capacity was resolved by classical vibration theory. The result showed that an increasing up to 0.4 volume percentage alumina content increases the damping capacity up to 34 percent. In another sample, addition of 2 weight percentage nano-Al2O3 particles showed big possibility in reducing CTE from 27.9-25.9×10 6 K 1 in Magnesium, tensile and yield strength amplified by 40MPa. In another test, Mg/1.1Al2O3 nanocomposite was manufactured by solidification process followed by hot extrusion. Results showed that strengthening effect was maintained up to 150 C and fracture characteristics of Mg composite transformed from brittle to mixed ductile mode and fully ductile in attendance of nano-Al2O3 particulates.
Enhancing the ductility of Mg-(5.6Ti+3Al) composite using nano-B4C addition and heat treatment
This study investigates the effects of nano-B 4 C addition and isothermal heat treatment on the microstructure and mechanical properties of Mg-(5.6Ti+3Al) composite developed through the disintegrated melt deposition method followed by hot extrusion. The developed Mg composites were characterized for their microstructural and mechanical properties in the as-extruded and heat treated conditions. Microstructural studies reveal no significant changes to the pre-existing Al 3 Ti intermetallic phases and the average grain size, due to nano-B 4 C addition. In the as-extruded condition, mechanical properties measurements showed large improvement in fracture strain without significant changes in strength properties due to nano-B 4 C addition. The best combination of strength and ductility observed in Mg-(5.6Ti+3Al)-2.5B 4 C composite was attributed to combined presence of nano-B 4 C particulates and Al 3 Ti intermetallics. In the isothermal heat-treated condition (200ºC for 5 hours), all the developed Mg composites exhibit significant enhancement in ductility with marginal reduction in strength due to the stress relaxation at matrix-reinforcement interface.