Electron beam melting (EBM) is a metal powder bed fusion additive manufacturing (AM) technology that facilitates the production of metal parts by selectively melting areas in layers of metal powder. The electron beam melting process is conducted in a vacuum chamber environment regulated with helium (He) at a pressure on the scale of 10⁻³ mbar. One of the disadvantages of vacuum environments is the effect of vapor pressure on volatile materials: indeed, elements in the pre-alloyed powder with high vapor pressure are at risk of evaporation. Increasing the He pressure in the process can improve the thermodynamic stability of the pre-alloyed components and decrease the composition volatility of the solid. However, increasing the pressure can also attenuate the electrons and consequently reduce the energy deposition efficiency. While it is generally assumed that the efficiency of the process is 90%, to date no studies have verified this. In this study, Monte Carlo simulations and detailed thermal experiments were conducted utilizing EGS5 and an Arcam Q20+ machine. The results reveal that increasing the gas pressure in the vacuum chamber by one order of magnitude (from 10⁻³ mbar to 10⁻² mbar) did not significantly reduce the energy deposition efficiency (less than 1.5%). The increase in gas pressure will enable the melting of alloys with high vapor pressure elements in the future.

中文翻译：

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EBM增材制造工艺中电子束能量沉积过程中气压的影响

电子束熔化（EBM）是一种金属粉末床熔融增材制造（AM）技术，通过选择性地熔化金属粉末层中的区域来促进金属零件的生产。电子束熔化过程是在真空室环境中进行的，该环境由氦气（He）调节，压力为10 ^-3毫巴 真空环境的缺点之一是蒸气压对挥发性材料的影响：实际上，具有高蒸气压的预合金粉末中的元素有蒸发的危险。在此过程中增加He压力可以改善预合金成分的热力学稳定性，并降低固体的组成挥发性。但是，增加压力也会使电子衰减，从而降低能量沉积效率。尽管通常认为该过程的效率为90％，但迄今为止，尚无研究证实这一点。在这项研究中，使用EGS5和Arcam Q20 +机器进行了蒙特卡洛模拟和详细的热实验。结果表明，真空室内的气压增加了一个数量级（从10开始^-3 mbar至10 ^-2 mbar）没有显着降低能量沉积效率（小于1.5％）。气压的增加将使将来具有高蒸气压元素的合金熔化。