Influence of introducing Zr, Ti, Nb and Ce elements on externally solidified crystals and mechanical properties of high-pressure die-casting Al–Si alloy

EXECUTIVE SUMMARY

高圧ダイカスト（HPDC）AlSi10MnMg合金は自動車産業で広く使用されています。Mgは熱処理によって鋳物の機械的特性を最適化できますが、熱応力の解放は大型一体型ダイカストの変形を引き起こします。そのため、熱処理を必要としないAl合金の開発が注目されています。また、HPDCには外部凝固結晶（ESCs）が含まれており、鋳物の機械的特性を損なう要因となっています。熱処理なしで高強度と靭性を備えたダイカストAl-Si合金を実現するために、AlSi9Mn合金を母材として、Zr、Ti、Nb、Ceを添加しました。それらがESCsと機械的特性に及ぼす影響を、三次元再構成と熱力学シミュレーションを通じて体系的に調査しました。その結果、Tiの添加はESCsのサイズと気孔率を増加させたのに対し、Nbの導入はESCsを微細化し、気孔率を減少させることが明らかになりました。一方、大型のAl3(Zr,Ti)相が形成され、機械的特性を低下させました。その後のCeの導入は、毒性効果を引き起こし、機械的特性をさらに低下させました。

要するに、この研究では、HPDC Al-Si合金において、TiとCeの添加は機械的特性に悪影響を及ぼし、Nbの添加はESCsの微細化と気孔率の減少に効果的であることを示しています。したがって、熱処理なしで高強度と靭性を確保するためには、合金元素の添加に慎重なアプローチが必要であることを示唆しています。

Influence of introducing Zr, Ti, Nb and Ce elements on externally solidified crystals and mechanical properties of high-pressure die-casting Al–Si alloy

Keywords : aluminium alloy high

Junjie Li, Wenbo Yu, Zhenyu Sun, Weichen Zheng, Liangwei Zhang, Yanling Xue, Wenning Liu & Shoumei Xiong 

Abstract

High pressure die casting (HPDC) AlSi10MnMg alloy castings are widely used in the automobile industry. Mg can optimize the mechanical properties of castings through heat treatment, while the release of thermal stress arouses the deformation of large integrated die-castings. Herein, the development of non-heat treatment Al alloys is becoming the hot topic. In addition, HPDC contains externally solidified crystals (ESCs), which are detrimental to the mechanical properties of castings. To achieve high strength and toughness of non-heat treatment die-casting Al–Si alloy, we used AlSi9Mn alloy as matrix with the introduction of Zr, Ti, Nb, and Ce. Their influences on ESCs and mechanical properties were systematically investigated through three-dimensional reconstruction and thermodynamic simulation. Our results reveal that the addition of Ti increased ESCs’ size and porosity, while the introduction of Nb refined ESCs and decreased porosity. Meanwhile, large-sized Al3(Zr,Ti) phases formed and degraded the mechanical properties. Subsequent introduction of Ce resulted in the poisoning effect and reduced mechanical properties.

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Tags: aluminum alloy; ,Aluminum Casting; ,Die casting; ,High pressure die casting; ,High pressure die casting (HPDC); ,Mechanical Property; ,Microstructure; ,Review; ,自動車産業; ,자동차; ,자동차 산업