Control of thermally stable core-shell nano-precipitates in additively manufactured Al-Sc-Zr alloys
Control of thermally stable core-shell nano-precipitates in additively manufactured Al-Sc-Zr alloys
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DOI：
10.1016/j.addma.2019.100910
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发表时间：
2020-03-01
影响因子：
11
通讯作者：
Raabe, Dierk
中科院分区：
文献类型：
--
作者：
Kuernsteiner, Philipp;Bajaj, Priyanshu;Raabe, Dierk
轻金属（如高强度铝基合金）的激光增材制造（LAM）为运输行业提供了巨大的潜力，例如重量减轻和相关的燃料消耗减少。通常，商业含Sc合金，如Scalmalloy（R），依赖于沉淀硬化来增加其强度。常规加工涉及受控老化，在此期间，有序且连贯的Al 3 Sc沉淀物从Sc过饱和固溶体形成。在这里，我们展示了如何本征热处理（IHT）的定向能量沉积（DED）可以用来触发沉淀的Al 3Sc已经在LAM过程中。在LAM中，由于冷却速度快，过饱和Al-Sc基体发生固态相变，可获得10（23）个纳米级/m3的高数量密度析出相。然而，IHT导致沉淀物粗化，从而降低其强化效果。我们实施替代的凝固条件，以利用IHT在Al 3Sc沉淀物周围形成富Zr壳，从而防止粗化。我们的方法适用于各种沉淀硬化合金，以在LAM期间触发原位沉淀。
Laser Additive Manufacturing (LAM) of light metals such as high-strength Al-based alloys offers tremendous potential for e.g. weight reduction and associated reduced fuel consumptions for the transportation industry. Typically, commercial Sc-containing alloys, such as Scalmalloy (R), rely on precipitation hardening to increase their strength. Conventional processing involves controlled ageing during which ordered and coherent Al3Sc precipitates form from a Sc-supersaturated solid solution. Here we show how the intrinsic heat treatment (IHT) of directed energy deposition (DED) can be used to trigger the precipitation of Al3Sc already during the LAM process. High number densities of 10(23) nano-precipitates per m(3) can be realized through solid-state phase transformation from the supersaturated Al-Sc matrix that results from the fast cooling rate in LAM. Yet, the IHT causes precipitates to coarsen, hence reducing their strengthening effect. We implement alternative solidification conditions to exploit the IHT to form a Zr-rich shell around the Al3Sc precipitates that prevents coarsening. Our approach is applicable to a wide range of precipitation-hardened alloys to trigger in-situ precipitation during LAM.