(燕山大學(xué) 亞穩(wěn)材料科學(xué)與技術(shù)國家重點(diǎn)實(shí)驗(yàn)室，秦皇島 066004)
摘 要: 采用X射線衍射技術(shù)測定了Inconel 718合金中δ相在980、 1 000和1 020 ℃時(shí)的溶解動(dòng)力學(xué)， 并采用掃描電鏡進(jìn)行了組織觀察。 結(jié)果表明： Inconel 718合金在980、 1 000和1 020 ℃保溫過程中， δ相含量逐漸降低， 經(jīng)1 020 ℃保溫2 h后， δ相可完全溶入基體； 當(dāng)溫度為980和1 000 ℃時(shí)， δ相的平衡含量分別約為3%及0.6%。 δ相的溶解過程可分為兩個(gè)階段， 溶解初期主要表現(xiàn)為長針狀δ相長度方向的斷裂，且很快溶解斷裂為短棒狀及顆粒狀， 同時(shí)在厚度方向上尺寸逐漸減小； 隨著溶解過程的進(jìn)行， 后續(xù)的溶解過程主要為短棒狀及顆粒狀δ相尺寸的減小。 δ相溶解動(dòng)力學(xué)過程的控制環(huán)節(jié)并非Nb或Ni原子的長程擴(kuò)散過程， 而為δ相分解的界面反應(yīng)過程。
關(guān)鍵字: Inconel 718合金； 溶解動(dòng)力學(xué)； 控制環(huán)節(jié)；擴(kuò)散； 界面反應(yīng)
inconel 718 alloy
（State Key Laboratory of Metastable Materials Science and Technology,
Yanshan University, Qinhuangdao 066004, China）
Abstract: The dissolution kinetics and microstructures evolution of δ phase in Inconel 718 alloy during holding at 980, 1 000 and 1 020 ℃ were analyzed using X-ray diffraction and scanning electron microscopy. The results indicate that the dynamic equilibrium state reaches after holding at 980 ℃ for more than 30 min and at 1 000 ℃ for more than 2 h, the equilibrium contents are 3.0% and 0.6%, respectively. Nearly, the δ phase dissolves into the austenitic matrix holding at 1 020 ℃ for more than 1 h. The dissolution process of needle-like δ phase can be divided into two stages, the initial stage is mainly characterized as the fracture from long needle shape to short bars or particles. Then, the size of δ phase with short bars or particles decrease at the following stage. The dissolution models of δ phase were established and the controlling step was revealed. The whole dissolution process is governed by the interface reaction mechanism, but not by the long-distance diffusion of Nb or Ni atoms in the austenite matrix.
Key words: Inconel 718 alloy; dissolution kinetics; controlling step; diffusion; interface reaction
