日本金属学会誌

J. Japan Inst. Metals, Vol. 76, No. 12 (2012),
pp. 677-683

Influence of Two-Step Aging on Cluster Formation and Tensile Property in Al-Mg-Si Alloy

Ken Takata1, Jun Takahashi2, Makoto Saga1, Kohsaku Ushioda3, Akira Hibino4 and Masao Kikuchi5

1Steel Research Laboratories, Nippon Steel Corporation, Futtsu 293-8511
2Advanced Technology Research Laboratories, Nippon Steel Corporation, Futtsu 293-8511
3Technical Development Bureau, Nippon Steel Corporation, Futtsu 293-8511
4Technical Research Center, Furukawa-Sky Aluminum Corporation, Fukaya 366-8511
5Research Center for Steel, Kyushu University, Fukuoka 819-0395

Abstract:

The change of the state of Mg-Si cluster with aging time at 303 K and 323 K after pre-aging at 363 K was studied by means of tensile test focusing on yield stress, 3DAP (3 Dimensional Atom Probe) and DSC (Differential Scanning Calorimetry) measurement. Mg-Si clusters formed during isothermal aging at the temperature of 363 K after solution treatment were different from the ones formed at the temperatures of 303 K and 323 K. During aging at 303 K and 323 K following pre-aging at 363 K, the cluster that was once formed at 363 K grew in size together with the new nucleation of another type of cluster formed at 303 K and 323 K. The increment of yield stress with aging time at 303 K and 323 K after pre-aging at 363 K was greater than the one without pre-aging at 363 K. This was considered to stem from the fact that the cluster formed during pre-aging at 363 K further grows during aging at 303 K and 323 K but at the same time the another type of cluster is supposed to newly nucleate and grow at 303 K or 323 K after pre-aging, both of which are inferred to contribute to the larger increase in yield strength.


(Received 2012/8/16)

Keywords:

aluminum-magnesium-silicon alloy, magnesium-silicon cluster, two-step aging, 3 dimensional atom probe (3DAP), differential scanning calorimetry (DSC), yield stress


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