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Ti , Zr and Sc aluminum alloy microstructure and properties of

Author: CuiHaiChao
Tutor: ZuoXiuRong
School: Zhengzhou University
Course: Materials Physics and Chemistry
Keywords: Ti， Zr， Sc Grain refinement Aging hardness Recrystallization Mechanical properties
CLC: TG146.21
Type: Master's thesis
Year: 2007
Downloads: 335
Quote: 2
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Abstract


Scandium is the best modifier to improve the performance of aluminum alloys. The aluminum alloys with minor scandium have the high strength, plastic, excellent welding properties, corrosion resistance and resistance to neutron irradiation damage performance. However, it is not widely used in the aluminum industry due to the high cost of scandium. Therefore, developing the high-performance aluminum alloys with low-level scandium has important practical significance, which lays the foundation for the large-scale deployment of scandium alloys.It has been found that, when 0.09%Ti, 0.13%Zr and 0.20%Sc are added to the pure aluminium, the alloys have stronger refining capacity, the grain diameter of 160μm, better than 0.13%Zr and 0.20%Sc or 0.09%Ti and 0.20%Sc added. When 0.2%Zr and 0.25%Sc are added to pure aluminum the alloys have stronger refining results, the grain diameter of 178μm, better than 0.20%Sc and 0.03%Ti additions. When 0.03%Ti, 0.2%Zr and 0.25%Sc are added jointly, the alloys have the best refining effect, the grain diameter of 148μm. 0.25%Sc is added to the aluminum alloys, increasing the tensile strength and yield strength significantly, from 63MPa to 173MPa and 47MPa to 139MPa, and also declining the elongation rate from 50% to 20%. Al-0.25%Sc and Al-0.03%Ti -0.25%Sc alloys have the equivalent strength, larger strength than Al-0.03%Ti-0.2%Zr-0.25%Sc and Al-0.2%Zr-0.25%Sc alloys. The beginning recrystallization temperatures of Al-0.03%Ti-0.25%Sc and Al-0.25%Sc alloys lie between 400°C and 500°C, and the beginning recrystallization temperatures of Al-0.2%Zr-0.25%Sc and Al-0.03%Ti-0.2%Zr-0.25%Sc are above 500°C. At 400°C aging, the microstructure of Al-0.25%Sc alloys have been blurred after 120 hours, and hardness declines greatly, becoming almost complete recrystallization. Al-0.03%Ti-0.25%Sc alloys become partial recrystallization after 120 hours aging at 400°C and Al-0.2%Zr-0.25%Sc and Al-0.03%Ti-0.2%Zr-0.25%Sc never recrystallize at 400°C aging. At 500°C aging, the hardness of Al-0.03%Ti-0.25%Sc and Al-0.25%Sc alloys is close to the minimum value after 72 hours, indicating having presented complete recrystallization. Al-0.2%Zr-0.25%Sc and Al-0.03%Ti-0.2%Zr-0.25%Sc alloys get the partial recrystallization for 120 hours at 500°C aging. Al-Ti-Zr-Sc and Al-Ti-Zr alloys can be obtained by electrolysis, using electrolytic equipment and industrial raw materials of aluminium, by adding titania, zirconia and scandium oxide. So direct electrolytic production of Al-Ti-Zr and Al-Ti-Zr-Sc alloys is feasible, and electrolytic Al-Ti-Zr-Sc alloys have finer grain and higher hardness than electrolytic Al-Ti-Zr alloys. Electrolytic samples have finer grain and higher hardness than the same component as-cast alloys.

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CLC: > Industrial Technology > Metallurgy and Metal Craft > Metallurgy and Heat Treatment > Metallic materials > Non - ferrous metals and their alloys > Light non-ferrous metals and their alloys > Aluminum
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