Mg96.17Zn3.15Y0.5Zr0.18合金高壓下固溶處理時(shí)效硬化研究

Mg96.17Zn3.15Y0.5Zr0.18合金高壓下固溶處理時(shí)效硬化研究AGE-HARDENING RESPONSE FOR Mg96.17Zn3.15Y0.5Zr0.18 SOLID SOLUTION ALLOY UNDER HIGH PRESSURE

在4 GPa 高壓下對(duì)Mg96.17Zn3.15Y0.5Zr0.18合金進(jìn)行600~800 ℃固溶處理, 之后在200 ℃進(jìn)行等溫時(shí)效處理. 利用 TEM, HRTEM, SEM, XRD 等分析方法研究了高壓固溶及隨后時(shí)效處理后合金的顯微組織, 并測(cè)試了 4 GPa 高壓下固溶處理后合金的時(shí)效硬化曲線. 結(jié)果表明, 在 4 GPa 高壓下固溶能大幅提高 Zn 在 Mg 基體中的溶解度, Zn 的溶解度由常壓下 400 ℃固溶后的 2.11% (質(zhì)量分?jǐn)?shù),下同) 提高到 4 GPa 高壓下 700~800 ℃固溶后的約6.60%, 獲得了過(guò)飽和 α-Mg 固溶體. 在隨后的200 ℃溫時(shí)效過(guò)程中, 高壓固溶合金 在較短的時(shí)間內(nèi)即可獲得較高的近峰值硬度, 4 GPa 下 800 ℃固溶的合金近峰值時(shí)效硬度高達(dá) 105 HV, 比 400 ℃固溶處理合金近峰時(shí)效硬度(81 HV)提高了約 30%. HRTEM 觀察表明, 4 GPa 高壓下固溶合金時(shí)效沉 淀析出相具有很高的析出密度, 且析出相中含有粒狀準(zhǔn)晶 I-Mg3Zn6Y 相.

Rare-earth (RE) element addition can remarkably improve the mechanical properties of magnesium alloys through solid solution and age-hardening. Increasing the solubility in the Mg matrix and enhancing the precipitation density are effective measures to improve aging strengthening of magnesium alloys. In this work, solid solution treatment at 600~800 ℃ under 4 GPa, and then isothermal aging at 200 ℃ for Mg96.17Zn3.15Y0.5Zr0.18 alloy was carried out. The microstructures of the high pressure solution treatment Mg96.17Zn3.15Y0.5Zr0.18 alloy before and after aging were investigated by TEM, HRTEM, SEM and XRD, and age-hardening curves of Mg96.17Zn3.15Y0.5Zr0.18 alloy after solution treatment under the high pressure of 4 GPa have been tested. The results show that, as the rise of the solution treatment temperature, I-Mg3Zn6Y and W-Mg3Zn3Y2 continually dissolved into the Mg matrix, and the solubility of Zn in the Mg matrix drastically improved after solution treatment under the high pressure of 4 GPa. The solubility of Zn in the Mg matrix reached up to 6.60% (mass fraction) after solution treatment at 700~800 ℃ under the high pressure of 4 GPa than 2.11% after solution treatment at 400 ℃ under the atmosphere, and the supersaturated solid solution α-Mg has been attained. After aging treatment at 200 ℃, the peak hardness of Mg96.17Zn3.15Y0.5Zr0.18 alloy after solution treatment under the high pressure of 4 GPa could been reached in short aging time, the peak hardness of the Mg96.17Zn3.15Y0.5Zr0.18 alloy after solution treatment at 800 ℃ under 4 GPa was 105 HV, which was increased by 30% than 81 HV of the alloy after solution treatment at 400 ℃ under the atmosphere. HRTEM analysis results indicated that the high precipitation density was found in the Mg96.17Zn3.15Y0.5Zr0.18 alloy after solution treatment under the high pressure of 4 GPa, and some of precipitation were particle quasicrystal I-Mg3Zn6Y phases.

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