Abstract

Properties, such as morphology, particle size, and hardness affect the ability of a powder to flow and bond to a surface in additive manufacturing (AM) applications. The effects of high energy ball milling on spherical copper and stainless steel powders were evaluated. Morphology of both stainless steel and copper powders, quantifiable by aspect ratio, showed larger changes due to ball-to-powder ratio (BPR, 2:1–1:10) compared to the total milling time (2–60 min). Hardness of copper increased from 53 HV_0.01 in the as-received condition to 96 HV_0.01 after milling for 60 min with a BPR of 1:1 or 2:1. Hardness of steel increased from 336 HV_0.01 in the as-received condition to 523 HV0.01 after milling for 60 min with a BPR of 2:1. Hardness of both powders was insensitive to milling times at low BPR (1:10). At high BPR (2:1), hardness of steel increases after just 2 min of milling, while Cu changed significantly only after 60 min. Hardness was influenced more by BPR than by milling time. It is shown that a broad range of milling parameters exist where metallic powders can be processed with minimal changes to their morphology, while controlling for hardness.

摘要

诸如形态，粒度和硬度之类的特性会影响粉末在增材制造（AM）应用中流动和粘结至表面的能力。评估了高能球磨对球形铜粉和不锈钢粉的影响。与总研磨时间（2-60分钟）相比，不锈钢和铜粉的形貌可通过长径比定量显示出较大的变化，这是由于球粉比（BPR，2：1-1：10）引起的。铜的硬度从原样的53 HV _0.01增加到以1：1或2：1的BPR研磨60分钟后的96 HV _0.01。钢的硬度从336 HV _0.01增加研磨60分钟后，BPR为2：1时，在523 HV0.01的原样条件下。两种粉末的硬度对低BPR（1:10）的研磨时间都不敏感。在高BPR（2：1）时，钢的硬度仅在铣削2分钟后就增加，而Cu仅在60分钟后才发生显着变化。BPR对硬度的影响大于铣削时间。结果表明，存在广泛的铣削参数，可以在控制硬度的情况下以最小的形态变化加工金属粉末。