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However, even when the BMG is in contact with the mold, the normal stress component still results in normal strains as long as the length scales involved are small compared to the thickness of the deforming BMG24. The presence of a normal component results in an outstanding surface finish (see, e.g., Fig. 2a), and it can also be utilized to pattern the surface, as demonstrated in Fig. 4c, allowing functionalization of the surfaces to be integrated into the blow mold process.Besides surface patterning, joining can also be integrated as a processing step during blow molding. In conventional metal processing, an additional processing step is required to join parts, which creates stresses and affects mechanical properties. Applying conventional joining techniques to BMGs is particularly problematic due to the metastable nature of their amorphous structure25,26. Alternatively joints can be created by blow molding around fastener sites, resulting in a mechanical bond (Fig. 4c). With blow molding, high strength bulk metallic glasses can be formed in a manner similar to plastics when the specifics of these alloys are considered.
This allows one to net shape complex geometries in an economical and precise manner, including shapes, which can not be produced with any other metal processing method. Furthermore, blow molding of BMGs enables combination of three traditional processing steps (shaping, joining, finishing) into one processing step. The superior properties of BMGs relative to plastics and typical structural metals, combined with the ease, economy, and precision Table 1 Processing parameters of BMGs, plastics, and SPF alloys. Examples for BMGs are Zr44Ti11Cu10Ni10Be25, Pt57.5Cu14.7Ni5.3P22.5, and Au49Ag5.5Pd2.3Cu26.9Si16.3, for plastic is polypropylene, for SPF alloys are Ti (6AL-4V) and Al (2004 SPF) alloys. Strain rates are 4x10-4 sec-1 for Ti SPF alloys and 5x10-3 sec-1 for Al SPF alloys. Parameter MaterialsPlastics BMG SPF alloysProcessing temperature [°C] 160 - 260 160 (Au-based)280 (Pt-based)350 (Pd-based)430 (Zr-based900 (Ti6Al4)18465 (Al 2004)Processing pressure [Pa]1 - 10 x 105 Pa 1 - 4 x 105 Pa 1 - 4 x 105 PaMaximum strain [%] ∞ ~10 000 <400Typical strain rate [s-1]10-1 - 1 10-1 10-3m ~1 1 0.4 - 0.7ms = d l—d og— Tg— (η//— TG)—⎥⎥⎥T=Tg1372052 (Pt-based)2170 (Zr-based)21Not applicableκ [W/mK] 0.3 10 170Instrument citationInstron, Instron #5569 with a 50 000 kN and 5000 kN load cell Shimadzu Lab-x, XRD-6000 diffractometer Perkin Elmer Diamond DSC of blow molding, have the potential to impact society in a manner similar to the development of synthetic plastics and their associated processing methods. AcknowledgmentsThe authors thanks NSF CMMI (MPM#0826445) for financial support and Robert Fers and Robert Martinez for their preparation of test samples. Fig. 4 By reducing the heat losses during deformation, shapes that cannot be produced with any other metal processing method can be precisely net shaped within < 1 minute through TPF based blow molding (a and b). Expansion of Zr44Ti11Cu10Ni10Be25 pre-shapes as shown in Fig. 3a result in hollow, low symmetry shapes that are seamless. (b) These include thin-walled shapes incorporating undercuts. Surface patterning and functionalization can be integrated into the blow molding processing step. (c) Joints can be created by blow molding around fastener sites, resulting in a mechanical bond. (d) Surface patterning or finishing can also be integrated into one processing step with the blow molding.
热塑性塑料吹塑金属成型
虽然塑料已经彻底改变了工业设计，但是由于其功能可加工性、和较低的强度阻碍了它们在结构部件上的使用。另一方面，当金属作为强大结构部件的几何形状的基础时，它们的处理是相当有限的。“理想”的材料可以提供一个优越的结构性能和多能力的组合。并且塑造复杂的几何形状。在这里，我们表明，散装金属玻璃（非晶合金），具有优越的力学性能，可以像塑料吹塑成型。增强BMG形成的关键是顺从它的热塑性成形。这允许BMG结构复杂，其中一些无法用任何其他金属的过程，被网形精确。论文网