本文選題：Cu　切入點：Ag　出處：《哈爾濱工業(yè)大學(xué)》2016年碩士論文　論文類型：學(xué)位論文

【摘要】：銅和銅合金經(jīng)過熱處理后具有較高的強度、電導(dǎo)率及耐高溫低周期疲勞等特性,在航空航天領(lǐng)域具有廣泛應(yīng)用。隨著航天事業(yè)的發(fā)展,火箭發(fā)動機內(nèi)襯材料所需更高的高溫、高壓、耐高溫低周期疲勞損傷等特性,現(xiàn)役的Cu Zr合金已不能滿足后續(xù)航天事業(yè)的要求,研發(fā)新的火箭發(fā)動機內(nèi)襯材料具有十分重要的意義。相比于Cu Zr合金,Cu Ag Zr合金具有更好的高溫力學(xué)性能,在航空航天領(lǐng)域是一種極具應(yīng)用價值的材料,Cu Ag Zr合金的熱處理工藝與合金的組織結(jié)構(gòu)及力學(xué)性能關(guān)系密切。本文通過XRD、DTA、光學(xué)顯微鏡、掃描電鏡、透射電鏡、室溫拉伸試驗、硬度測試等手段,系統(tǒng)的研究Cu Ag Zr合金不同熱處理工藝制度、時效析出行為及力學(xué)性能。研究發(fā)現(xiàn),熱擠壓態(tài)Cu Ag Zr合金有α-Cu基體和β-Ag與m相形成的共晶第二相,第二相呈帶狀沿著晶界不連續(xù)分布,并具有一定的方向性。隨著固溶溫度升高、保溫時間延長,第二相由帶狀變?yōu)榫W(wǎng)狀,球狀,溶入基體中。同時,合金晶粒尺寸逐漸長大。Cu Ag Zr合金最佳固溶溫度為940℃,固溶時間為10h。當(dāng)固溶溫度為960℃時,合金過燒。透射電鏡觀察發(fā)現(xiàn),納米Ag析出相形核長大變化規(guī)律如下:時效初期,球狀納米Ag析出相優(yōu)先于位錯上非均勻形核;隨著時效時間的延長或時效溫度的升高,球狀納米Ag析出相數(shù)量逐漸增多并長大;當(dāng)球狀納米Ag析出相長大到一定尺寸,球狀納米Ag析出相在{100}面沿著011或011?延長成為桿狀;當(dāng)長度到一定程度,在過飽和的Cu基體無位錯區(qū)中,新的納米Ag析出相與拉長的納米Ag析出相形核,并沿著相同的011或011?方向繼續(xù)生長。時效時間的繼續(xù)延長或時效溫度的繼續(xù)升高,納米Ag析出相進(jìn)入粗化階段。TEM觀察表明,時效過程存在不同時效析出相。在相同保溫時間下脫溶序列為:球狀納米Ag析出相→桿狀納米Ag析出相→盤狀納米Cu Zr析出相→粒狀富Zr析出相。在相同時效溫度下脫溶序列為:球狀納米Ag析出相→桿狀納米Ag析出相→盤狀富Zr析出相。硬度測試及室溫拉伸試驗研究表明,Cu Ag Zr合金強度隨著固溶溫度的升高,保溫時間的延長而逐漸上升,當(dāng)溫度超過過燒溫度,合金強度塑性急劇下降,不同固溶工藝下,合金都具有較高的延伸率。Cu Ag Zr合金在時效過程中,350℃時效,隨著時效時間的延長,屈服強度、抗拉強度和硬度均呈現(xiàn)單調(diào)上升趨勢;當(dāng)溫度超過400℃,隨著時效時間的延長,合金屈服強度、抗拉強度和硬度先升高后降低,延伸率單調(diào)下降。在相同時效時間下,強度和硬度都隨著時效溫度的升高呈現(xiàn)先升高后降低趨勢。隨著時效溫度的升高,時效峰所需時間迅速縮短。當(dāng)時效溫度超過700℃,合金硬度降到未時效以下。
[Abstract]:Copper and copper alloys are widely used in aerospace field because of their high strength, electrical conductivity and low cycle fatigue resistance after heat treatment. With the development of aerospace industry, the lining materials of rocket engine need higher temperature. Due to the characteristics of high pressure, high temperature and low cycle fatigue damage, the current Cu-Zr alloy can no longer meet the requirements of the subsequent aerospace industry. It is of great significance to develop new liner materials for rocket motor. Compared with Cu Zr alloy, Cu Ag Zr alloy has better mechanical properties at high temperature. The heat treatment process of CuAg-Zr alloy, which is a valuable material in the field of aerospace, is closely related to the microstructure and mechanical properties of the alloy. In this paper, the X-ray DTA, optical microscope, scanning electron microscope, transmission electron microscope, room temperature tensile test were used. By means of hardness measurement, the precipitation behavior and mechanical properties of Cu-Ag-Zr alloy under different heat treatment conditions were systematically studied. It was found that there were 偽 -Cu matrix and eutectic second phase formed by 尾 -Ag and m phase in hot extruded Cu-Ag Zr alloy. The second phase is distributed discontinuous along the grain boundary and has a certain directivity. With the increase of the solution temperature and the prolongation of the holding time, the second phase changes from banded to reticulate, globular and dissolved into the matrix, at the same time, The optimum solution temperature is 940 鈩，

本文編號：1597010