本文選題：原始粉末顆粒邊界　切入點：熱等靜壓成形　出處：《中北大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：FGH96合金是我國研制的第二代粉末高溫合金,該合金具有優(yōu)異的裂紋擴展抗力、蠕變強度以及損傷容限等性能,是制造大推重比航空發(fā)動機渦輪盤等熱端部件的首選材料。使用氬氣霧化法(AA)或旋轉(zhuǎn)電極法(PREP)制備的FGH96合金粉末,經(jīng)熱等靜壓成形后組織中一般會存在原始粉末顆粒邊界(PPB),PPB是粉末高溫合金的三大缺陷之一,對合金的組織和性能非常不利。本文圍繞FGH96合金中的PPB,開展了以下工作:(1)以粉末粒度和粉末氧含量為熱等靜壓成形(HIP)變量,研究了PPB的形成機理及影響因素。研究表明,PPB是由粉末表面吸附的C、O以及表面富集的Ti、Cr、Al的氧化物在HIP時與內(nèi)部遷移的Ti、Nb等元素一起形成的邊界聚集物,主要由大尺寸γ′相和少量的氧化物、碳化物或碳氧化物組成;熱等靜壓成形時,PPB沿粉末顆粒邊界析出,PPB的析出程度受粉末粒度影響較小,與粉末氧含量成正比。(2)以HIP態(tài)的FGH96合金為研究對象,通過熱變形(HIF)和熱處理(HT)試驗研究了PPB的演變規(guī)律。研究表明,PPB處的大尺寸γ′相以及組織內(nèi)的二、三次γ′相在熱變形和熱處理過程中逐漸融入基體,轉(zhuǎn)而析出大量小尺寸γ′相和一些碳化物、氧化物或碳氧化物。(3)通過原位拉伸和原位疲勞試驗,研究了FGH96合金的損傷力學(xué)行為。研究表明,原位拉伸試驗過程中,材料處于過載狀態(tài),斷裂特征為沿PPB發(fā)生的脆性斷裂;原位疲勞試驗過程中,疲勞裂紋的萌生、擴展由滑移、孿晶及晶界主導(dǎo),疲勞斷口瞬斷區(qū)有沿PPB開裂的斷裂特征,材料的疲勞壽命與PPB相對等級成反比。
[Abstract]:FGH96 alloy is the second generation powder superalloy developed in China. It has excellent crack growth resistance, creep strength and damage tolerance. FGH96 alloy powder prepared by argon atomization method or rotating electrode method is the preferred material for the manufacture of hot end parts such as turbine disk of aeroengine with large push-weight ratio. After hot isostatic pressing, there are usually three defects in the microstructure of the powder superalloy, which are the original powder particle boundary and the PPB. In this paper, the following work has been carried out around the FGH96 alloy: the powder size and the oxygen content of the powder are taken as the variables of hot isostatic pressing forming (hip). The formation mechanism and influencing factors of PPB were studied. The results show that the PPB is a boundary aggregate formed by the Con O adsorbed on the powder surface and the oxides enriched on the surface of TiOCr-Al during HIP, along with the elements such as TiONb, which are transported internally, and so on. It is mainly composed of large size 緯 'phase and a small amount of oxides, carbides or carbon oxides, and the precipitation degree of PPB along the boundary of powder particles is less affected by particle size during hot isostatic pressing. The evolution of HIP alloy was studied by means of hot deformation and heat treatment. The results showed that the large size 緯 'phase and the two phases in the structure of PPB were studied. The cubic 緯 'phase gradually melts into the matrix during hot deformation and heat treatment, and in turn precipitates a large number of small 緯' phases and some carbides, oxides or carbon oxides. The damage mechanical behavior of FGH96 alloy has been studied. The results show that during in-situ tensile test, the material is in a state of overload and the fracture is characterized by brittle fracture along PPB, and during in situ fatigue test, the fatigue crack initiation and propagation are caused by slip. The twinning and grain boundary are dominant, and the fracture characteristics of the transient fracture zone of fatigue fracture are along PPB. The fatigue life of the material is inversely proportional to the relative grade of PPB.
【學(xué)位授予單位】：中北大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TG132.3;TF123.71

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