Performance comparison of AlTiC and AlTiB master alloys in grain refinement of commercial and high purity aluminum

Friction stir processing (FSP) is one of the severe plastic deformation (SPD) processes. It has been reported that SPD-processed Al with various purities attained a minimum grain size when Zener-Hollomon parameter is larger than 1016 s-1. The minimum grain size is different by purity level and alloying elements. We investigated the influence of Fe solute atoms on grain refinement of high-purity Al on the condition that Zener-Hollomon parameter was larger than 1016 s-1. FSP was conducted on Al-0.01%Fe, which was fabricated by using 5N Al (99.999% purity). FSP-ed Al-0.01%Fe exhibits the minimum grain size of 1.4 μm, although high-purity aluminums with more than 99.998% exhibits much larger minimum grain sizes of 30-40 μm. Only 101 at.ppm Fe played a critical role in the grain refinement of pure aluminums.

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Photopyroelectric Measurement of the Thermal Diffusivity of Recrystallized High Purity Aluminum

Research in Nondestructive Evaluation ◽

10.1080/09349849108968041 ◽

1991 ◽

Vol 3 (1) ◽

pp. 69-80

Author(s):

S. B. Peralta ◽

S. C. Ellis ◽

C. Christofides ◽

A. Mandeiis ◽

H. Sang ◽

...

Keyword(s):

Thermal Diffusivity ◽

High Purity ◽

High Purity Aluminum

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The influence of gadolinium on Al–Ti–C master alloy and its refining effect on AZ31 magnesium alloy

International Journal of Materials Research (formerly Zeitschrift fuer Metallkunde) ◽

10.1515/ijmr-2020-7779 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Wenxue Fan ◽

Hai Hao

Keyword(s):

Mechanical Properties ◽

Magnesium Alloy ◽

Grain Refinement ◽

Magnesium Alloys ◽

Master Alloy ◽

Cast Alloy ◽

Az31 Magnesium Alloy ◽

Synthesis Mechanism ◽

Refining Effect ◽

Master Alloys

Abstract Grain refinement has a significant influence on the improvement of mechanical properties of magnesium alloys. In this study, a series of Al–Ti–C-xGd (x = 0, 1, 2, 3) master alloys as grain refiners were prepared by self-propagating high-temperature synthesis. The synthesis mechanism of the Al–Ti–C-xGd master alloy was analyzed. The effects of Al–Ti–C-xGd master alloys on the grain refinement and mechanical properties of AZ31 (Mg-3Al-1Zn-0.4Mn) magnesium alloys were investigated. The results show that the microstructure of the Al–Ti–C-xGd alloy contains α-Al, TiAl3, TiC and the core–shell structure TiAl3/Ti2Al20Gd. The refining effect of the prepared Al–Ti–C–Gd master alloy is obviously better than that of Al–Ti–C master alloy. The grain size of AZ31 magnesium alloy was reduced from 323 μm to 72 μm when adding 1 wt.% Al–Ti–C-2Gd master alloy. In the same condition, the ultimate tensile strength and elongation of as-cast alloy were increased from 130 MPa, 7.9% to 207 MPa, 16.6% respectively.

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Microstructural Evolutions of 2N Grade Pure Al and 4N Grade High-Purity Al during Friction Stir Welding

Materials ◽

10.3390/ma14133606 ◽

2021 ◽

Vol 14 (13) ◽

pp. 3606

Author(s):

Tomoya Nagira ◽

Xiaochao Liu ◽

Kohasaku Ushioda ◽

Hidetoshi Fujii

Keyword(s):

Friction Stir Welding ◽

Dynamic Recrystallization ◽

Grain Refinement ◽

High Purity ◽

Cube Texture ◽

Grain Structure ◽

Welding Temperature ◽

Friction Stir ◽

Continuous Dynamic Recrystallization ◽

Dislocation Annihilation

The grain refinement mechanisms along the material flow path in pure and high-purity Al were examined, using the marker insert and tool stop action methods, during the rapid cooling friction stir welding using liquid CO2. In pure Al subjected to a low welding temperature of 0.56Tm (Tm: melting point), the resultant microstructure consisted of a mixture of equiaxed and elongated grains, including the subgrains. Discontinuous dynamic recrystallization (DDRX), continuous dynamic recrystallization (CDRX), and geometric dynamic recrystallization are the potential mechanisms of grain refinement. Increasing the welding temperature and Al purity encouraged dynamic recovery, including dislocation annihilation and rearrangement into subgrains, leading to the acceleration of CDRX and inhibition of DDRX. Both C- and B/-type shear textures were developed in microstructures consisting of equiaxed and elongated grains. In addition, DDRX via high-angle boundary bulging resulted in the development of the 45° rotated cube texture. The B/ shear texture was strengthened for the fine microstructure, where equiaxed recrystallized grains were fully developed through CDRX. In these cases, the texture is closely related to grain structure development.

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