A Swiss research team has formulated a novel bulk metallic glass (BMG) with the properties needed to be 3D printed into high-quality precious metal parts.
Using a palladium (Pd)-based BMG powder and conventional LPBF 3D printer, the engineers have been able to fabricate crack-free samples with a density of 99.6%, and a natural mirror-like finish. Given that the team’s prototypes required less than 70g of material to print, they could act as a precursor to an affordable new range of additive manufactured jewellery and watchmaking components in future.
BMGs in jewellery production
Due to their high corrosion and oxidation resistance, as well as their non-allergic nature, pure precious metals are in many ways ideal materials for manufacturing jewellery. However, such alloys also tend to exhibit low resistance to wear and scratching, and these are critical deficiencies when it comes to creating high-value consumer products.
我虽然已经进行了实际的研究nto developing precious alloys with better properties, this has previously proved difficult even after several thermo-mechanical treatments. BMGs, by contrast, are increasingly being viewed as a promising alternative to crystalline parts due to their amorphous nature, which prevents them from being impacted by dislocation and grain boundary defects.
尽管最初的BMG可以追溯到70多年来，但这些结构通常是通过常规铸造创建的，限制了可能生产的零件的大小。与此同时，使用LPBF 3D打印，在理论上可以在防止其结晶的同时打印BMG，从而产生耐用的无定形零件，但是到目前为止，该过程仅适用于铁和铝等金属。
为了评估添加剂制造在高级黄金和银基BMG生产中的全部潜力，因此，瑞士雷电竞充值团队试图确定用于创建高度不汤的钯结构的最佳参数集，此外还有热方差的临界点导致部分形状和几何不规则。
优化的贵金属印刷
最初,using single line tracks, the researchers were able to determine the ideal parameters for their experiments, which turned out to be at a laser power level of 40-60W, with anything higher than 80W resulting in print deceleration. Having identified the optimal set up, the team proceeded to fabricate twelve samples each measuring 5 x 5 x 1mm3，但早期原型表现出高度刻板的形状。
To correct this distortion, the researchers introduced a one-second wait between the printing of each layer, giving the samples time to cool between successive laser tracks. Interestingly, upon later dissection, each of the test specimens featured an amorphous in structure, but the part produced at 60W proved to have the widest processing window, validating the team’s earlier hypothesis.
为了利用其最终参数集，工程师通过3D打印3mm x 4mm圆柱体将测试包裹起来，孔隙率仅为0.4％。但是，团队确实承认，他们的结果可能会受到μCT扫描的分辨率的影响，并且标本的抗压强度比铸造的替代方案少14％，证明需要进一步优化过程。
What’s more, summary kinetic analysis revealed that the researchers’ parts crystallized more slowly than they could be processed, suggesting that cross-contamination and powder atomization may have impacted on their findings, thus the issue warrants investigation before such BMGs can be deployed as an end-use precious metal substitute.
“Despite the good glass-forming ability of Pd-based BMGs, the critical aspects in LPBF fabrication for avoiding crystallization are not so much the thermal conditions, but the absence of impurities,” concluded the team in their paper. “[Our] work illustrates how the combination of precious metals, amorphous state and AM can lead to promising applications, especially in the jewellery and watch industries.”
The multifunctionality of BMGs
Given the inherent malleability and corrosion-resistant qualities of amorphous alloys, it’s no surprise that significant research is now being conducted into developing defect-free BMGs. At theHuazhong University of Science and Technology（hust）例如，研究人员已经制作了自己的粉末，可以将3D印刷到scalable BMG structures。
Just last year, Chinese scientists also developed a combined ultrasonic vibration-assisted, thermoplastic forming and 3D printing approach to producingreinforced BMG composites。Using the novel process enabled the team to create sandwich-structured titanium alloy-reinforced parts, which proved to be much tougher than conventional monolithic BMGs.
Elsewhere,Fabrisonichas iteratively developed its Ultrasonic Additive Manufacturing (UAM) technology, which is capable of合并不同的无定形合金。作为最近一项NASA研究的一部分，该公司能够将不同的金属与结晶底物相连，从而增强了强度，耐腐蚀性和潜在的航空航天应用。
The researchers’ findings are detailed in their paper titled “Additive manufacturing of a precious bulk metallic glass。” The study was co-authored by Navid Sohrabi, Jamasp Jhabvala, Güven Kurtuldu, Ruggero Frison, Annapaola Parrilli, Mihai Stoica, Antonia Neels, Jörg F. Löffler and Roland E.Logé.
在项目期间，研究是在Swiss Federal Institute of Technology Lausanne(EPFL),ETH ZurichandSwiss Federal Laboratories for Materials Science and Technology(EMPA).
要了解最新的3D印刷新闻，请不要忘记订阅3D Printing Industry newsletteror follow us onTwitteror liking our page onFacebook。
要深入研究添加剂制造，您现在可以订阅我们的雷电竞充值YouTubechannel, featuring discussion, de-briefs and shots of 3D printing in-action.
Are you looking for a job in the additive manufacturing industry? Visit3D Printing Jobsfor a selection of roles in the industry.
特色图显示了研究人员的初始3D打印BMG样品。通过今日应用材料的照片。
