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摘要: 718 合金是二十世纪六十年代发展起来的沉淀硬化型铁-镍-铬基变形高温合金，我国的牌号为GH4169。该合金制成的零部件在热处理的高温固溶条件下会出现较严重的氧化， 生产检验时常因严重的氧化缺陷而报废。本实验是将718合金分别在810℃和910℃条件下在箱式电阻炉中进行分别进行1h和10h恒温氧化，再进行XRD和SEM表征，研究了其氧化表面和横截面形貌及机理，主要结论为718合金在910℃氧化10h后样品表面主要由Ti0.95Nb0.95O4 +Cr2O3+(Cr.Fe)2O3的复杂相组成。随着氧化时间和氧化温度的增加，试样氧化更加完全，氧化膜更加厚。62087
718 合金内氧化影响区中深灰色的部分为Al2O3。其氧化机制是由元素的扩散决定的。在氧化膜表面，Cr离子会不断向外扩散，而外界的O离子也会透过外氧化膜向试样内部缓慢扩散。形成内氧化区。并且由于 IN718合金中加入了较多的 Mo 和 Nb，它们形成的氧化物易挥发，容易使表层氧化物损伤破坏，促使氧化向内部进行， 也会导致合金外表层氧化物结构和内层氧化物结构。在高温氧化的初期，形成外层氧化物；随着氧化时间增加，氧化膜增厚，应力也随之增加。这种机械应力将会导致氧化膜破裂，O将会沿着晶界或相界扩散并与 Cr 形成氧化物造成内部氧化， 这会导致元素 Cr 向晶界或相界扩散，进而使合金元素分布也产生了不均匀的现象。
毕业论文关键词：718合金；氧化性；合金元素
Study on a new type of high temperature oxidation behavior of 718 Alloy
Abstract：718 Alloy is developed in the 1960s precipitation hardening Fe - Ni - Cr based deformation of high temperature alloy and our grades for GH4169. The parts made of the alloy can be severely oxidized under high temperature solid solution under heat treatment, and the production test is often abandoned due to severe oxidation defects. In this experiment, the alloy 718 were in 810 DEG C and 910 DEG C in the box type resistance furnace are respectively for 1H and 10h isothermal oxidation, and then were characterized by XRD and SEM on its surface oxidation and cross section morphology and mechanism of and main conclusions for alloy 718 910 c oxidation after 10h in the sample surface is mainly composed of a complex Ti0.95Nb0.95O4 +Cr2O3+(Cr.Fe)2O3was phase composition. With the increase of oxidation time and oxidation temperature, the sample oxidation is more complete, and the oxide film is thicker.
718 the oxidation mechanism of the alloy is determined by the diffusion of the elements. Because of the more Mo and Nb into the IN718 alloy, they formed oxides volatile, easy to make the surface oxide damage, prompt oxidized into the inner, lead alloy surface oxide layer structure and the inner oxide structure. In the early stage of high temperature oxidation, the formation of the outer oxide; with the increase of oxidation time, the oxide film is thickened, the stress also increases. This machinery should force will lead to the breakdown of the oxide film, O will be along the grain boundary and phase boundary diffusion and with Cr formed oxide caused by internal oxidation, which will lead to CR elements to grain boundaries or phase boundary diffusion, and the alloy elements distribution uneven phenomenon. The effect of internal oxidation section for Al2O3 deep gray.
Keywords: 718 Alloy;Oxidation; alloying element
目录
1、绪论 1
1.1高温合金 1
1.1.1高温合金简述 1
1.1.2高温合金发展历程 1
1.1.3高温合金分类 2
1.1.4合金元素的作用 2
1.2 高温合金氧化