Grain refinement mechanism of as-cast aluminum by hafnium

Li, Hongying; Li, Dewang; Zhu, Zhixiang; Chen, Baoan; Chen, Xin; Yang, Changlong; Zhang, Hongyu; Kang, Wei

doi:10.1016/s1003-6326(16)64438-2

Cited by 23 publications

(12 citation statements)

References 40 publications

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“…A range of microalloying elements were demonstrated to enhance strength, fatigue, and creep resistance of aluminum alloys. This includes small additions of the transition metals Sc [ 154 ], Zr [ 155 ], Cd [ 156 ], Nb [ 157 ], Ti [ 158 ] and the rare-earth elements Ce [ 159 ], Hf [ 160 ], Yb [ 161 ], and Er [ 162 ]. Scandium and zirconium were of particular interest due to their grain refining effect.…”

Section: Aluminum Alloys For Waammentioning

confidence: 99%

Review of Aluminum Alloy Development for Wire Arc Additive Manufacturing

et al. 2021

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Processing of aluminum alloys by wire arc additive manufacturing (WAAM) gained significant attention from industry and academia in the last decade. With the possibility to create large and relatively complex parts at low investment and operational expenses, WAAM is well-suited for implementation in a range of industries. The process nature involves fusion melting of a feedstock wire by an electric arc where metal droplets are strategically deposited in a layer-by-layer fashion to create the final shape. The inherent fusion and solidification characteristics in WAAM are governing several aspects of the final material, herein process-related defects such as porosity and cracking, microstructure, properties, and performance. Coupled to all mentioned aspects is the alloy composition, which at present is highly restricted for WAAM of aluminum but received considerable attention in later years. This review article describes common quality issues related to WAAM of aluminum, i.e., porosity, residual stresses, and cracking. Measures to combat these challenges are further outlined, with special attention to the alloy composition. The state-of-the-art of aluminum alloy selection and measures to further enhance the performance of aluminum WAAM materials are presented. Strategies for further development of new alloys are discussed, with attention on the importance of reducing crack susceptibility and grain refinement.

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Section: Aluminum Alloys For Waammentioning

confidence: 99%

Review of Aluminum Alloy Development for Wire Arc Additive Manufacturing

et al. 2021

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“…For instance, from the viewpoint of compositional design, research has shown that rare earth elements offer significant advantages when added to Al alloys, leading to optimized properties [13][14][15][16][17][18][19][20]. Within the realm of rare-earth elements, hafnium (Hf) stands out as a particularly promising candidate for grain refinement.…”

Section: Introductionmentioning

confidence: 99%

Sustainability through Optimal Compositional and Thermomechanical Design for the Al-7XXX Alloys: An ANOVA Case Study

Ijaz,

Nashri,

Qamash

2024

Sustainability

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The quest for lightweight, high-performance structural materials for demanding applications such as in the fields of automotive, aerospace, and other high-tech and military industries pushes the boundaries of material science. The present work aims to draw attention to a novel, sustainable manufacturing approach for the development of next-generation 7xxx series aluminum alloys that have higher strength by rejuvenating a sustainable compositional and thermomechanical processing strategy. Our innovative strategy integrates two key synergies: trace hafnium (Hf) addition for microstructural refinement, unique thermomechanical treatment involving cryorolling, and a short annealing method. Experimental results revealed that our base alloy exhibited a 33 µm grain size and impressive initial mechanical properties (334 MPa UTS, 150 HV). Adding 0.6 wt.% Hf and employing 50% cryorolling with short annealing led to a remarkable 10 µm grain size reduction and significant mechanical property leaps. The resulting alloy boasts a 452 MPa UTS and 174 HV, showcasing the synergistic advantageous effect of Hf and cryorolling plus annealing treatment. The developed alloys were compositional- and work hardening-dependent, leading to a rich mix of strengthening mechanisms. Optical and scanning electron microscopy reveal several intermetallic phases within the fcc matrix, wherein the Al3Hf phase plays a key role in strengthening by impeding dislocation movement. In addition to experimental results, a 12-full-factorial design experiment via ANOVA analysis was also utilized to validate the significant influence of Hf and cryorolling on properties with (p-values < 0.05). Among the different parameters, cryorolling plus annealing appeared as the most noteworthy factor, followed by the composition. Using the regression model, the ultimate tensile strength and hardness were predicted to be 626 MPa UTS and 192 HV for an alloy with 0.6 wt.% Hf and 85% cryorolling, which opens a new avenue for ultra-high-strength Al7xxx alloys.

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“…The formation of L1 2 -structured Al 3 Hf can inhibit grain boundary and subgranular boundary migration, or serve as a nucleating agent to refine grains. This effectively enhances the strength of aluminum alloys [11][12][13]. Molybdenum (Mo) can be involved in synthesizing intermediate phases enriched with transition metal elements.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation of Phase Equilibria in the Al–Mo–Hf Ternary System at 400 °C and 600 °C

Liu,

Yu,

Liu

et al. 2024

Processes

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This study investigates the phase equilibria of the Al-Mo-Hf ternary system at 400 °C and 600 °C using X-ray diffraction (XRD) and electron probe microanalysis (EPMA/WDS) techniques. Seven three-phase and five two-phase regions were identified at 400 °C, while eight three-phase and four two-phase regions were identified at 600 °C. Despite variations in the solid solubility ranges of certain compounds, the distribution of phase zones in the isothermal cross-section remained consistent at both temperatures. Using the experimental results and logical deductions, isothermal cross-sections were constructed for the Al-Mo-Hf ternary system at 600 °C and 400 °C.

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Grain refinement mechanism of as-cast aluminum by hafnium

Cited by 23 publications

References 40 publications

Review of Aluminum Alloy Development for Wire Arc Additive Manufacturing

Review of Aluminum Alloy Development for Wire Arc Additive Manufacturing

Sustainability through Optimal Compositional and Thermomechanical Design for the Al-7XXX Alloys: An ANOVA Case Study

Experimental Investigation of Phase Equilibria in the Al–Mo–Hf Ternary System at 400 °C and 600 °C

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