本文選題：純鎢　切入點(diǎn)：等溫退火　出處：《合肥工業(yè)大學(xué)》2017年碩士論文　論文類(lèi)型：學(xué)位論文

【摘要】：鎢基材料被認(rèn)為是聚變反應(yīng)堆中面向等離子體材料(PFMs,如第一壁和偏濾器材料)的候選材料之一,其在高溫服役條件下,可能會(huì)發(fā)生回復(fù)、再結(jié)晶和晶粒長(zhǎng)大的現(xiàn)象而改變材料微觀組織,引起材料性能的退化,如強(qiáng)度降低和再結(jié)晶脆化。這不僅關(guān)系到材料使用壽命,還會(huì)影響到核聚變裝置的服役安全性。因此研究純鎢在高熱條件下的損傷行為,具有重要的科學(xué)價(jià)值和工程意義。本文主要利用較高溫度下等溫退火實(shí)驗(yàn)來(lái)等效模擬聚變堆中高溫服役條件,對(duì)純鎢在高溫下的機(jī)械性能和顯微組織演變進(jìn)行了研究,并預(yù)測(cè)了其服役壽命。通過(guò)對(duì)純鎢退火后的機(jī)械性能演變的研究表明,隨著變形量的增加,再結(jié)晶溫度會(huì)下降,50%、67%和90%(W50、W67和W90)軋制比純鎢表觀再結(jié)晶溫度點(diǎn)大約分別為1307℃、1130℃和1072℃左右。隨著變形量增大,回復(fù)驅(qū)動(dòng)力變大,回復(fù)動(dòng)力學(xué)系數(shù)也越大,回復(fù)階段硬度下降地也越快。等溫退火過(guò)程中,硬度呈單調(diào)下降,再結(jié)晶體積分?jǐn)?shù)單調(diào)上升,溫度越高變形量越大,再結(jié)晶過(guò)程也越快。用經(jīng)典JMAK方程描述了上述變形純鎢的再結(jié)晶動(dòng)力學(xué)過(guò)程,并計(jì)算出W50、W67和W90表觀再結(jié)晶激活能Q為478KJ/mol,496KJ/mol和447KJ/mol,分別預(yù)測(cè)出W50、W67和W90在900℃時(shí)的使用壽命分別為172.7年、72.3年和8.5年,說(shuō)明W50的使用壽命更長(zhǎng)。通過(guò)對(duì)純鎢在等溫退火條件下的顯微組織演變的研究表明,變形量一定時(shí),退火溫度越高,再結(jié)晶晶粒尺寸越大;而退火溫度一定時(shí),軋制量越大,再結(jié)晶晶粒尺寸越小。初始軋制態(tài)組織的取向?qū)υ俳Y(jié)晶晶粒取向有很大影響,再結(jié)晶晶粒排布可以部分遺傳初始軋制晶粒排布的取向。原始晶粒的大小影響著再結(jié)晶晶粒組織大小,隨著軋制量的增加,原始軋制態(tài)平均晶粒尺寸減小,組織更加均勻,變形產(chǎn)生的位錯(cuò)增加,再結(jié)晶形核位點(diǎn)增加,再結(jié)晶晶粒增多,從而可以獲得細(xì)小的再結(jié)晶等軸晶組織。XRD表明W90軋制板材RD/ND面變形過(guò)程中形成強(qiáng)烈的(110)基面織構(gòu),在1350℃等溫退火時(shí),(110)基面織構(gòu)強(qiáng)度先減弱后增強(qiáng),但總體來(lái)說(shuō)仍處于減弱狀態(tài)。EBSD結(jié)果說(shuō)明軋制純鎢再結(jié)晶退火過(guò)程是大量的低角度晶界向高角度晶界轉(zhuǎn)變的過(guò)程,原始軋制態(tài)低角度晶界大量存在,完全再結(jié)晶態(tài)下晶界取向差滿(mǎn)足隨機(jī)取向分布。
[Abstract]:Tungsten based materials are considered to be candidates for plasma oriented PFMs in fusion reactors, such as first wall and filter materials, which may recover under high temperature service conditions. The phenomena of recrystallization and grain growth change the microstructure of the material and cause degradation of the properties of the material, such as reduced strength and recrystallization embrittlement. It also affects the service safety of nuclear fusion devices. Therefore, the damage behavior of pure tungsten under high heat condition is studied. It has important scientific value and engineering significance. In this paper, the mechanical properties and microstructure evolution of pure tungsten at high temperature are studied by using the isothermal annealing experiment at high temperature to simulate the high temperature service conditions of fusion reactor. The evolution of mechanical properties after annealing of pure tungsten shows that with the increase of deformation, The recrystallization temperature will decrease by 67% and 90% respectively. The apparent recrystallization temperature of pure tungsten is about 1307 鈩，

本文編號(hào)：1634751