一次時效溫度對新型高強(qiáng)耐蝕GH925合金顯微組織和力學(xué)性能的影響Effects of primary aging temperature on microstructures and mechanical properties of new corrosion-resistant alloy GH925 with high strength

為了研究一次時效溫度對新型高強(qiáng)耐蝕GH925合金顯微組織和力學(xué)性能的影響，利用熱力學(xué)計算軟件Thermo-Calc對合金中可能析出的平衡相及相組成進(jìn)行計算并分析，采用超高分辨率場發(fā)射掃描電鏡及附帶能譜儀、掃描電鏡和金相顯微鏡對合金中的析出相和沖擊斷口形貌進(jìn)行觀察。結(jié)果表明：一次時效溫度對GH925合金中σ相和γ′相的析出行為影響顯著；一次時效溫度升高不僅會促進(jìn)σ相在晶界上的大量析出并向晶內(nèi)生長，而且會引起γ′相的粗化，導(dǎo)致合金強(qiáng)度和韌性降低；晶界σ相引起的脆化效應(yīng)是導(dǎo)致沿晶斷裂的根本原因。

In order to study the effect of primary aging temperature on the microstructures and mechanical properties of a new corrosion-resistant alloy GH925, the precipitated equilibrium phases and their compositions were calculated and analyzed by Thermo-Calc software, and the precipitated phases and impact fracture morphology were observed by ultra high resolution field emission scanning electron microscopy (FESEM) and energy dispersive spectrometry (EDS), scanning electron microscopy (SEM) and metallographic microscopy. The results show that the primary aging temperature has significant effect on the precipitation behaviors of σ phase and γ′ phase. The increase of primary aging temperature not only promotes the precipitation of a large number of σ phase at the grain boundary and its growth to the inner of the grain, but also leads to the coarsening of γ′ phase, giving rise to the decreases of strength and toughness. The root reason for the intergranular fracture is the embrittlement effect caused by σ phase at the grain boundary.

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