快速退火對TiAlCrNbVZr系中熵合金微結構和機械性質影響之研究;Effect of rapid heating rate annealing on the microstructure and mechanical properties of TiAlNbCrVZr medium-entropy alloy

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Title:	快速退火對TiAlCrNbVZr系中熵合金微結構和機械性質影響之研究;Effect of rapid heating rate annealing on the microstructure and mechanical properties of TiAlNbCrVZr medium-entropy alloy
Authors:	宋庭瑋;Song, Ting-Wei
Contributors:	機械工程學系
Keywords:	輕量化中熵合金;非等原子比;熱機處理;light-weight HEAs;non-equiatomic;thermomechanical treatment
Date:	2023-07-19
Issue Date:	2024-09-19 17:34:38 (UTC+8)
Publisher:	國立中央大學
Abstract:	延續先前實驗室設計之Ti65(AlCrNbV)28Zr7中熵合金，本研究目的希望就其成分基礎上微調合金組成，以提升整體機械性能去設計出能達到降伏強度>1200 MPa以及塑性能維持15 %。首先將選定之元素，用高溫電弧融煉技術鑄成具有簡單固溶相之六元Ti65AlxCryNbzVwZr7 (x, y, z, w: 4, 4, 10, 10)中熵合金，觀察調整Al, Cr, Nb與V各元素含量對整體微結構與機械性質之影響，並透過滾軋製程使其厚度降低累積應變能，再將其以短時間退火熱處理使材料晶粒細化，藉由分析微結構與機械性質探討其強化機制，找出最合適的加工製程與熱處理參數。根據先前實驗室研究Ti含量多寡對強度的變化，並且觀察調整Al, Cr, Nb與V各元素含量對整體械性質之影響後，設計出Ti60Al10Cr4Nb10V9Zr7這組合金。研究結果顯示，鑄造態的Ti60Al10Cr4Nb10V9Zr7皆為單一BCC相，並能達到1000 MPa以上的降伏強度與20.0 %以上的拉伸塑性。將此合金以熱機處理強化，使用的加工製程參數是先將材料進行50 %熱滾軋，再透過80 %冷滾軋。本實驗中，在材料以50 %熱滾軋及80%冷軋後，以25°C/s升溫速率下進行退火熱處理能達到期望之機械性質，能達到1212MPa與15.0%的延性。 ;The purpose of this study is to fine tune the alloy composition based on the previous study Ti65Al7Cr7Nb7V7Zr7 medium entropy alloy (MEA) by modify the Al, Cr, Nb and V content. The Ti65AlxCryNbzVwZr7 (x, y, z, w: 4, 4, 10, 10) MEA will maintained density close to 5 g/cm3, yield strength of 1200 MPa and plastic strain maintained above 15%. All of the as-cast Ti65AlxCryNbzVwZr7 (x, y, z, w: 4, 4, 10, 10) MEA were single BCC structure. Based on previous research on the effect of Ti content on strength and observing the influence of adjusting the content of Al, Cr, Nb, and V elements on overall mechanical properties, we designed the material Ti60Al10Cr4Nb10V9Zr7. According to the experimental test results, as-cast Ti60Al10Cr4Nb10V9Zr7 MEA is single BCC phases, and can achieve yield strength above 1000 MPa with tensile ductility above 20.0%. To strengthen this alloy through thermal mechanical treatment, the MEA was first hot rolled 50%, involve subjecting the material first to 50% and followed to cold 80%. Then the as-rolled sample were annealed at a heating rate of 15 and 25°C/s to modify the microstructure. The optima mechanical properties occurs at 700°C which are yield strength 1212MPa, ductility 15%.
Appears in Collections:	[Graduate Institute of Mechanical Engineering] Electronic Thesis & Dissertation

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