急速凝固 Al-Cr-Zr-Ti鋁合金之製造及其性質分析

Abstract

Rapid Solidified Process(R S P)製造的鋁合金通常用於須耐高溫、質 輕的航空用途上，。本篇論文使用R S P 中的平流鑄造法，製造以 Al-4.5Cr-xZr-yTi(wt﹪)為基本組成的鋁合金薄帶。在R S P的平流鑄造 法中，坩堝的噴口尺寸及和銅輪的間距以及銅輪轉速會影響薄帶之過冷度 和厚度。本實驗以 Al- 4.5Cr-3Zr、Al-4.5Cr-3Zr-0.5Ti、Al-4.5Cr-3 Zr-1.0Ti、Al- 4.5Cr-4.5Zr-1.5Ti、及Al-4.5Cr-1.5Ti(wt﹪)等五種原 料在相同銅輪轉速、液相熔漿溫度、噴出壓力、坩堝的噴口尺寸及和銅輪 的間距下製造急冷薄帶。本文以Vicker's硬度計、DSC(示差掃描熱量計) 、X-ray繞射儀、TEM(電子顯微鏡)等儀器分析在不同含量 Zr及Ti 添加 下對薄帶性質之影響。在進一步熱處理之下，可以得知 Al-Cr-Zr-Ti 合金析出物為 L12-Al3(Zr、Ti)及 Al13Cr2，其析出溫度隨Zr、Ti的加 入量不同而有所變化，以熱差掃描熱量計(DSC)測量析出物的放熱波峰溫 度大致分別為 430℃及530℃，以TEM觀察亦有不同面貌。且Al-4.5Cr- XZr-YTi合金中，因 Ti 加入導致硬度曲線有兩個 Peak值，但因有關文獻 對此方面的探討較少，希望經由本實驗了解Ti在鋁合金中的貢獻。 Rapidly Solidified (RS) aluminum alloy are currently being developed for high-temperature、light-weight aero space industry 。In this thesis,planar flow casting process was employed to fabricate RS ribbon based on the composition Al-4.5Cr -xZr-yTi ( wt﹪).In the planar flow casting,the size of nozzle、the gapbetween nozzle and cupper wheel and the velocity of cupperwheel will affect the resultant ribbon thickness and thedegree of undercooling.In the present work all Al-4.5Cr-xZr- yTi ribbon were produced under similar conditions,i.e.thecupper wheel speed,melt temperature ,nozzle size and the gapbetween nozzle and cupper wheel. The properties of as-formed ribbons were examined by Vicker's hardness tester、DSC(Differential scanning calori- metry、X-ray diffractometer and TEM( Transmission Electron Microscope).After heat-treatment、the precipitates of ribbon were found to be L12-Al3(Zr,Ti) and Al13 Cr2.Theprecipition temperature of Al3Zr and Al13Cr2 vary with theZr and Ti content.The precipition temperatures are 430℃and 530℃. The hardness curves present two peaks as a results of Ti addition.This effect,with little relatedliterature,requires further study.