本文關(guān)鍵詞： 鎳基單晶高溫合金 低密度 微觀組織 力學(xué)行為　出處：《沈陽(yáng)大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：本文設(shè)計(jì)了一種低密度鎳基單晶高溫合金,采用螺旋選晶法制備了[001]取向鎳基單晶試棒,利用光學(xué)顯微鏡(OM)、掃描電鏡(SEM)、透射電鏡(TEM)、差示掃描熱分析(DSC)等研究了鎳基單晶合金鑄態(tài)與熱處理態(tài)組織、典型條件下瞬時(shí)拉伸性能和高溫低應(yīng)力蠕變性能。對(duì)合金的鑄態(tài)組織研究發(fā)現(xiàn),合金中共晶含量約為0.7vol%,一次枝晶間距約為265mm,略低于典型的第二代單晶高溫合金;采用排水法測(cè)量合金的密度為8.2g/cm3,顯著低于典型二代單晶;采用DSC法和金相法測(cè)定了合金的初熔溫度,并通過(guò)不同時(shí)間的固溶處理確定了合金的固溶時(shí)間,最終制定了合理的熱處理制度:1350℃/1h+1360℃/5h+空冷→1080℃/5h+空冷→900℃/8h+空冷。研究了合金完全熱處理后γ和γ'兩相微觀組織,結(jié)果表明,合金完全熱處理后,γ'相的平均尺寸約為0.3mm,體積分?jǐn)?shù)為65vol%,γ基體寬度約為45nm;SEM和TEM觀察表明合金基體并未寬化也沒(méi)有二次γ'相析出。研究了合金在室溫、中溫和高溫三個(gè)典型溫度下的拉伸行為,結(jié)果表明,合金在室溫和中溫(760℃)拉伸時(shí)應(yīng)力應(yīng)變曲線上出現(xiàn)鋸齒流變現(xiàn)象(PLC效應(yīng)),曲線上的鋸齒波主要為C型波;對(duì)合金在不同溫度下拉伸斷口分析表明,室溫為典型的解理斷裂,中溫(760℃)為純剪切斷裂,高溫(1100℃)為微孔聚集型斷裂;同時(shí)對(duì)合金在典型高溫低應(yīng)力蠕變條件下的蠕變行為研究表明,合金蠕變斷裂后γ'相發(fā)生筏化,在1050℃/200MPa和1100℃/137MPa條件下筏化γ'相厚度分別為0.7mm和1mm;合金在上述兩種條件下均出現(xiàn)拓?fù)涞怪矛F(xiàn)象,其NA(γ')值分別為-0.04mm-2和-0.06mm-2;合金蠕變斷裂模式均為微孔聚集型斷裂。
[Abstract]:In this paper, a low density nickel base single crystal superalloy was designed. [001] oriented nickel base single crystal test rod was prepared by spiral crystal selection method. The as-cast and heat-treated microstructure of Ni-base single crystal alloy was studied by optical microscope, scanning electron microscope (SEM), transmission electron microscope (TEM) and differential scanning calorimetry (DSC). Under typical conditions, the transient tensile properties and creep properties at high temperature and low stress were studied. It was found that the eutectic content of the alloy was about 0.7 voll, and the primary dendrite spacing was about 265 mm, which was slightly lower than that of the typical second generation single crystal superalloy. The density of the alloy measured by drainage method is 8.2 g / cm 3, which is significantly lower than that of the typical second generation single crystal, the initial melting temperature of the alloy is measured by DSC and metallography, and the solution time of the alloy is determined by solution treatment at different time. Finally, a reasonable heat treatment system was worked out: 1: 1350 鈩，

本文編號(hào)：1505350