Investigation of Microstructural Factors Affecting the Plane-Strain Fracture Toughness of Mg-Zn-Y-Al Alloys Processed by Consolidation of Rapidly Solidified Ribbons
Investigation of Microstructural Factors Affecting the Plane-Strain Fracture Toughness of Mg-Zn-Y-Al Alloys Processed by Consolidation of Rapidly Solidified Ribbons
复制标题
影响快凝带固结Mg-Zn-Y-Al合金平面应变断裂韧性的显微组织因素研究
DOI：
10.1007/978-3-030-72432-0_8
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Kawamura Yoshihito
中科院分区：
文献类型：
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作者：
Nishimoto Soya;Yamasaki Michiaki;Inoue Shin-ichi;Kawamura Yoshihito
采用快速凝固（RS）带固结法制备了具有较高断裂韧性的Mg96.75Zn0.85Y2.05Al0.35（at%）高强度纳米晶块状合金。在~1.4 × 105Ks−1的冷却速率下，将单辊熔融纺丝制备的RS带压入铜坯中，然后进行热挤压固结。合金的显微组织由α-Mg相和长周期有序堆积相组成。预固/挤压热处理条件影响合金的两相组织演变。在未进行预挤压热处理的合金中，晶粒内部析出板状的LPSO相。另一方面，在预挤压热处理合金中，在晶界周围形成块状的LPSO相。块状LPSO相的形成引起裂纹偏转和弯曲，从而提高断裂韧性。经~738 K预挤压热处理24 h的合金具有良好的平面应变断裂韧性（KIc= ~15 mpam /2）和抗拉屈服强度（σ0.2= ~400 MPa）平衡。
High strength nanocrystalline bulk Mg96.75Zn0.85Y2.05Al0.35(at%) alloys featuring increased fracture toughness were fabricated by the consolidation of rapidly solidified (RS) ribbons. The RS ribbons prepared by single-roller melt-spinning at a cooling rate of ~1.4 × 105Ks−1were pressed into a copper billet and then consolidated by hot-extrusion. The microstructure of the alloys consists of α-Mg and long-period stacking ordered (LPSO) phases. The two-phase microstructure evolution in the alloys is influenced by conditions of pre-consolidation/extrusion heat treatment. In the alloys without pre-extrusion heat treatment, plate-shaped LPSO phase precipitates in grain interior. On the other hand, in the alloys with pre-extrusion heat treatment, block-shaped LPSO phase forms around grain boundaries. Formation of the block-shaped LPSO phase induces crack deflection and meandering, resulting in improvement of fracture toughness. The alloy subjected to pre-extrusion heat treatment at ~738 K for 24 h exhibited a good balance of plane-strain fracture toughness (KIc= ~15 MPam1/2) and tensile yield strength (σ0.2= ~400 MPa).