低密度雙相富鋁高熵合金之微結構觀察與其機械性質研究;Microstructure and mechanical properties of low density dual-phase Al-rich high entropy alloys

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Title:	低密度雙相富鋁高熵合金之微結構觀察與其機械性質研究;Microstructure and mechanical properties of low density dual-phase Al-rich high entropy alloys
Authors:	李兆修;Li, Chao-Hsiu
Contributors:	材料科學與工程研究所
Keywords:	高熵合金;低密度;雙相;富鋁;固溶;high entropy alloys;low density;dual-phase;Al-rich;solid solution
Date:	2019-08-20
Issue Date:	2019-09-03 14:50:23 (UTC+8)
Publisher:	國立中央大學
Abstract:	本研究旨在設計中低密度高熵合金之成分，探討Al Ti Cr Mn V 各個元素對於此合金系統的微結構、熱穩定和機械性質等影響。為設計密度低於5 g/cm3 的低密度合金，以Al為主要成分，配合高熵合金之設計參數規範，加入Ti Cr Mn V 四種元素，以不同比例添加至四元及五元合金。　　經XRD微結構分析得知AlTiCrMn、AlTiCrMnV系列合金皆可成為BCC加FCC雙相固溶體，根據合金比例不同，其硬度落在250至500 Hv，其中以Al50(TiCrMn)45V5具有最佳的機械性質表現，其硬度值為355Hv，藉由SEM影像分析計算其相比例隨著Ti Cr Mn的變化及由EDS分析雙相中的元素分別含量之結果可詳知Ti為FCC穩定劑，Cr Mn V為BCC穩定劑，此外發現添加V之後，在400至1000度之間有優異的相熱穩定性，更進一步得知最佳的均質化溫度為800°C。在壓縮測試中，Al50(TiCrMn)45V5擁有最大的壓縮強度為1900MPa，降伏強度為900MPa，壓縮延性為32%。;This study aims to design the high entropy alloy with low density. Investigate the effect of each element of Al Ti Cr Mn V on the microstructure, thermal stability and mechanical properties, etc. To reach the goal of alloy density less than 5 g/cm3, aluminum was designated as the main element and follows with the design specification of high entropy alloys to add titanium, chromium, manganese and vanadium to from the quaternary alloy or quinary alloys. The XRD results show that AlTiCrMn and AlTiCrMnV series alloys can form dual-phase solid solution (BCC and FCC). The hardness varies from 250 to 500 Hv according to the different alloy compositions. Additionally, we can figure out the effect of Ti Cr Mn additive on BCC and FCC by phase proportion calculation from SEM image analyses as well as the semiquantitative analysis by EDS. Titanium is regarded as FCC stabilizer and the elements of chromium, manganese and vanadium are regarded within BCC stabilizer. Moreover, the addition of vanadium can increase the thermal stability of phase in 400 to 1000°C. The optimum homogenization temperature is 800°C. Al50(TiCrMn)45V5 show the best mechanical properties in compression test, 900MPa of yield strength, 1900Mpa of ultimate strength , and 32% plastic strain.
Appears in Collections:	[Institute of Materials Science and Engineering] Electronic Thesis & Dissertation

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