(北京科技大學(xué) 材料科學(xué)與工程學(xué)院, 北京 100083)
摘 要: 研究了鎢含量為36％, Ni與Fe質(zhì)量比為7/3和9/1的兩種W-Ni-Fe三元合金的預(yù)應(yīng)變時效硬度變化規(guī)律, 用X射線衍射鑒定了時效后兩種合金的物相組成, 并用透射電鏡觀察其微觀結(jié)構(gòu)。 結(jié)果表明： Ni與Fe質(zhì)量比為7/3的W-Ni-Fe三元合金在800℃下進行預(yù)應(yīng)變時效時, 硬度隨時間增加而單調(diào)降低; 相同條件下Ni與Fe質(zhì)量比為9/1的W-Ni-Fe三元合金時效初期硬度下降, 但隨時間延長硬度又逐步提高。 X射線衍射物相鑒定和透射電子顯微分析發(fā)現(xiàn)： Ni與Fe質(zhì)量比為7/3的合金在預(yù)應(yīng)變時效過程中沒有明顯沉淀析出物, 其時效硬度下降是固溶度降低、 殘余應(yīng)力消除以及回復(fù)與再結(jié)晶的結(jié)果; 而Ni與Fe質(zhì)量比為9/1的合金經(jīng)預(yù)應(yīng)變時效后析出了細小彌散的β相, 其硬度變化存在兩種機制， 一種是固溶度降低、 殘余應(yīng)力消除和回復(fù)與再結(jié)晶引起軟化, 另一種是細小β相沉淀析出導(dǎo)致彌散強化。
關(guān)鍵字: W-Ni-Fe; 預(yù)應(yīng)變時效; β相
（School of Materials Science and Engineering,
University of Science and Technology Beijing, Beijing 100083, China）
Abstract:The hardness variation of two kinds of alloys with 36% tungsten content and 7/3, 9/1 nickel-to-iron mass ratios during strain aging at 800℃ was studied. The microstructures of the aged alloys were analyzed by XRD and TEM. The results show that the strain aging hardness of W-Ni-Fe ternary alloy with 7/3 nickel-to-iron mass ratio decreases monotonically with the increase of aging time. Under the same conditions, however, the hardness of 9/1 nickel-to-iron mass ratio alloy decreases in the initial aging stage, and then increases as aging process goes on. XRD and TEM analysis show that there isn’t any precipitation depositing from the alloy with 7/3 nickel-to-iron mass ratio during aging. The monotonic decrease in hardness of this alloy during aging process results from the recovery, recrystallization and solid solubility declining. In the alloy of 9/1 nickel-to-iron mass ratio, the fine β phase precipitates dispersively during aging. Therefore, there are two different kinds of mechanisms influencing the hardness of the alloy with 9/1 nickel-to-iron mass ratio, one is recovery, recrystallization and solid solubility declining course, which softens the alloy, and the other one is the dispersion strengthening effect induced by the deposition of β phase, which hardens the alloy. These two mechanisms result in the hardness variation of the alloy with 9/1 nickel-to-iron mass ratio as mentioned above.
Key words: W-Ni-Fe; strain aging; β phase
