Cabeza Sandra, Garcés Gerardo, Pérez Pablo, Adeva Paloma
Department of Non-Destructive Testing, Federal Institute for Materials Research and Testing BAM, Unter den Eichen 87, 12205 Berlin, Germany; Department of Physical Metallurgy, National Center for Metallurgical Research CENIM (CSIC), Av. Gregorio del Amo 8, 28040 Madrid, Spain.
Department of Physical Metallurgy, National Center for Metallurgical Research CENIM (CSIC), Av. Gregorio del Amo 8, 28040 Madrid, Spain.
J Mech Behav Biomed Mater. 2015 Jun;46:115-26. doi: 10.1016/j.jmbbm.2015.02.022. Epub 2015 Feb 27.
Microstructure, mechanical properties and corrosion behaviour of WZ21 (%wt) alloy prepared by a powder metallurgy route from rapidly solidified powders have been studied. Results were compared to those of the same alloy prepared through a conventional route of casting and extrusion. The microstructure of the extruded ingot consisted of α-Mg grains and Mg3Zn3Y2 (W-phase) and LPSO-phase particles located at grain boundaries. Moreover, stacking faults were also observed within α-Mg grains. The alloy processed by the powder metallurgy route exhibited a more homogeneous and finer microstructure, with a grain size of 2 μm. In this case W-phase and Mg24Y5 phase were identified, but not the LPSO-phase. The microstructural refinement induced by the use of rapidly solidified powders strengthened the alloy at room temperature and promoted superplasticity at higher strain rates. Corrosion behaviour in PBS medium evidenced certain physical barrier effect of the almost continuous arrangements of second phases aligned along the extrusion direction in conventionally processed WZ21 alloy, with a stable tendency around 7 mm/year. On the other hand, powder metallurgy processing promoted significant pitting corrosion, inducing accelerated corrosion rate during prolonged immersion times.
研究了通过粉末冶金路线由快速凝固粉末制备的WZ21（重量百分比）合金的微观结构、力学性能和腐蚀行为。将结果与通过传统铸造和挤压路线制备的相同合金的结果进行了比较。挤压铸锭的微观结构由α-Mg晶粒以及位于晶界处的Mg3Zn3Y2（W相）和LPSO相颗粒组成。此外，在α-Mg晶粒内也观察到了堆垛层错。通过粉末冶金路线加工的合金表现出更均匀、更细小的微观结构，晶粒尺寸为2μm。在这种情况下，鉴定出了W相和Mg24Y5相，但未发现LPSO相。使用快速凝固粉末引起的微观结构细化在室温下强化了合金，并在较高应变速率下促进了超塑性。在PBS介质中的腐蚀行为证明，在传统加工的WZ21合金中，沿挤压方向排列的第二相几乎连续排列具有一定的物理屏障作用，腐蚀速率稳定在每年7mm左右。另一方面，粉末冶金加工促进了明显的点蚀，在长时间浸泡期间导致腐蚀速率加快。
