Effect of Aging on the Microstructure and Mechanical Properties of 1460 Alloy

doi:10.1007/s40195-015-0219-7

Abstract

Abstract:

Effects of the aging temperature on the hardening response, the tensile properties and the precipitate microstructure evolution of 1460 alloy were studied in this work. It was found that Al₃ (Sc, Zr) and δ′ (Al₃Li) phases were precipitated from the matrix at the very early aging stage, while the precipitation of T1 (Al₂CuLi) and θ′ (Al₂Cu) was much slower than that of the δ′ phase. When aging at higher temperature (160 and 190 °C), the δ′, T1 and θ′ phases tended to form simultaneously and grow up very quickly. Conversely, the δ′ and θ″ (Al₂Cu) phases were precipitated separately and more dispersive at lower aging temperature (130 °C). Taken together, the alloy aged at 160 °C exhibited improved mechanical properties owing to the uniform dispersion of the fine T1 precipitates.

Key words: Al-Li alloy, Precipitate, Precipitation hardening process, Mechanical property

Juan Ma, De-Sheng Yan, Li-Jian Rong, Yi-Yi Li. Effect of Aging on the Microstructure and Mechanical Properties of 1460 Alloy[J]. Acta Metallurgica Sinica (English Letters), 2015, 28(4): 454-459.

Figures/Tables 7

Fig. 1 Age hardening curves for 1460 alloy aged at 130, 160 and 190 °C

Fig. 2 Tensile strength and elongation as function of aging time at 190 °C a, 160 °C b

Fig. 3 SAED patterns (along [110]Al) of the samples aged at 190 °C for 30 min a, 2 h b, 10 h c

Fig. 4 TEM images (along [110]Al) of the samples aged at 190 °C for 30 min a, 2 h b, 10 h c, 20 h d

Fig. 5 BF and DF images taken along [110]Al of samples aged at 160 °C for different time: a, d 4 h; b, e 24 h; c, f 60 h

Fig. 6 BF images taken along [100]Al of samples aged at 130 °C for 8 h a, 24 h b, 72 h c, 84 h d, DF image taken along [100]Al of sample aged at 130 °C for 84 h e

Table 1 Summary of the features of the aging at different temperatures

Temperature	Advantage	Disadvantage	Others
130 °C	(1) High nucleation rate (2) Smaller and more dispersive precipitates	(1) Precipitates are difficult to grow up (2) T1 phase hardly shows up	δ′ and θ″ precipitate separately
160 and 190 °C	(1) Short peak-aging time (2) Precipitates nucleate and grow up easily and quickly	(1) Precipitates are apt to have big size (2) δ′ phase is easily over-aged	δ′ appears earlier; θ′ and T1 come into being later; θ″ is hardly seen

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