その場中性子回折によるLPSO型マグネシウム合金の特異な塑性変形挙動の観測

Evaluation of specific plastic deformation behavior for LPSO-type magnesium alloy by in-situ neutron diffraction

諸岡 聡  ; Gong, W.; Harjo, S.   ; 相澤 一也  

Morooka, Satoshi; Gong, W.; Harjo, S.; Aizawa, Kazuya

本研究は動的な引張-圧縮間その場中性子回折を用いて濃度変調と構造変調を伴ったシンクロ型LPSOマグネシウム合金の可逆繰り返し硬化挙動を調査することを目的とする。最大引張応力と最大圧縮応力は繰返し数の増加に伴い上昇し、繰返し数200回時の最大引張応力と最大圧縮応力はそれぞれ+97.4 and -176.7MPaである。これは、最大圧縮応力が圧縮変形時に生じる双晶(キンク帯)の影響により最大引張応力よりも大きくなったと示唆しており、このキンク帯は、動的な引張-圧縮間の()結晶粒群の積分強度の変化から可逆的生成・消滅が生じている証拠が本実験手法により得られている。

Recently, magnesium alloys containing a Mg-Zn-Y long-period stacking ordered (LPSO) phase structure have been reported to exhibit excellent mechanical properties, including high strength and reasonable ductility. It is very important to determine the differences in plastic deformation behaviors, mechanical properties by existing of LPSO phase structure and their origin of deformation mechanism induced by the crystal structures. In this study, the reversible cyclic hardening behavior of LPSO-type magnesium alloys is investigated using TOF neutron diffraction during dynamic tension-compression cyclic loading conditions at constant 0.5 % strain amplitude. The peak stresses in both tension and compression were observed to increase gradually up to the 200th cycle. At the 200th tension-compression cycle, tension and compression peak stresses are approximately +97.4 and -176.7 MPa, respectively. The peak stress for the compression was observed to be larger than that for the tension, suggesting that kinking accompanying with hardening was occurred by compression deformation. The evidence of reversible deformation behavior was obtained from the change in individual () integrated intensity during real-time tension-compression cyclic testing.