Nd含量對Mg-6Gd-2.5Y-0.5Zr合金顯微組織和力學(xué)性能的影響

Nd含量對Mg-6Gd-2.5Y-0.5Zr合金顯微組織和力學(xué)性能的影響Effects of Nd addition on microstructure and mechanical properties of Mg-6Gd-2.5Y-0.5Zr alloy

通過金相觀察、X射線衍射、透射電鏡、硬度測試和拉伸性能測試等實驗方法，研究添加不同含量的Nd元素對Mg-6Gd-2.5Y-0.5Zr合金的顯微組織、時效硬化行為以及峰值時效下力學(xué)性能的影響。結(jié)果表明：隨著Nd含量的增加，鑄態(tài)合金中第二相Mg5(Gd/Y)和Mg24(Gd/Y)5 的含量顯著增加，合金經(jīng)固溶淬火后，時效強化現(xiàn)象越來越顯著，峰值時效時間縮短，峰值時效硬度明顯增加。當(dāng)Nd元素的含量為1.0%(質(zhì)量分數(shù))，合金的力學(xué)性能最佳，Mg-6Gd-2.5Y-1Nd-0.5Zr的抗拉強度為289 MPa，屈服強度為241 MPa。時效硬化行為和峰值時效力學(xué)性能得到改善，其主要是因為加入Nd元素后，在α-Mg基體中形成大量的β′相，且β′相明顯細化，β′相的形貌也發(fā)生改變。

The effects of Nd addition on microstructure, age-hardening behavior and mechanical properties of Mg-6Gd-2.5Y-0.5Zr alloy were investigated by optical microscopy (OM), X-ray diffractometry (XRD), transmission electron microscopy (TEM), hardness test and tensile tests. The results show that the amount of second phase (Mg5(Gd/Y) and Mg24(Gd/Y)5) increase significantly in the as-cast alloys, and the age hardening response after quenched is improved apparently with the addition of Nd, the hardness is enhanced and time to peak ageing is shortened. The Mg-6Gd-2.5Y-1Nd-0.5Zr alloy exhibits the maximum yield strength of 241 MPa and ultimate tensile strength of 289 MPa. The reason for the improvement of age-hardening behavior and mechanical properties is the higher number density and finer β′ precipitates in the α-Mg matrix, and morphologies of β′ precipitates also change with Nd addition.

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