Site-specific atom probe tomography (APT) from aluminum alloys has been limited by sample preparation issues. Indeed, Ga, which is conventionally used in focused-ion beam (FIB) preparations, has a high affinity for Al grain boundaries and causes their embrittlement. This leads to high concentrations of Ga at grain boundaries after specimen preparation, unreliable compositional analyses and low specimen yield. Here, to tackle this problem, we propose to use cryo-FIB for APT specimen preparation specifically from grain boundaries in a commercial Al-alloy. We demonstrate how this setup, easily implementable on conventional Ga-FIB instruments, is efficient to prevent Ga diffusion to grain boundaries. Specimens were prepared at room temperature and at cryogenic temperature (below approx. 90K) are compared, and we confirm that at room temperature, a compositional enrichment above 15 at.% of Ga is found at the grain boundary, whereas no enrichment could be detected for the cryo-prepared sample. We propose that this is due to the decrease of the diffusion rate of Ga at low temperature. The present results could have a high impact on the understanding of aluminum and Al-alloys.

铝合金的定点原子探针断层扫描 (APT) 受到样品制备问题的限制。事实上，通常用于聚焦离子束 (FIB) 制备的 Ga 对 Al 晶界具有高亲和力，并导致其脆化。这导致样品制备后晶界处的 Ga 浓度较高、成分分析不可靠以及样品产率低。在这里，为了解决这个问题，我们建议使用冷冻 FIB 来专门从商用铝合金的晶界制备 APT 样品。我们演示了这种可在传统 Ga-FIB 仪器上轻松实现的设置如何有效地防止 Ga 扩散到晶界。对室温和低温（约低于 90K）制备的样品进行比较，我们确认在室温下，在晶界处发现了高于 15 at.% 的 Ga 成分富集，而没有检测到富集对于冷冻制备的样品。我们认为这是由于低温下Ga扩散速率降低所致。目前的结果可能会对铝和铝合金的理解产生重大影响。