(陜西理工大學(xué) 材料科學(xué)與工程學(xué)院，漢中 723000)
摘 要: 利用X射線衍射儀(XRD)、金相顯微鏡、萬能試驗(yàn)機(jī)和掃描電鏡(SEM)等儀器研究在不同熱處理溫度下Zr44Co56合金顯微組織和力學(xué)性能。結(jié)果表明：在不同熱處理溫度下，試樣顯微組織由基體B2相和第二相B33相所組成；在熱處理溫度723、773和823 K下，B33相相對含量相對于鑄態(tài)合金呈增加趨勢；當(dāng)熱處理溫度達(dá)到873 K時，少量的B33相在晶界處析出；隨熱處理溫度增高，顆粒形狀由鑄態(tài)的小塊狀變?yōu)榇志€條狀，再到細(xì)條狀。試樣在723 K下熱處理后，其屈服強(qiáng)度和線彈性極限值均大于鑄態(tài)合金的相應(yīng)值，而試樣在773、823和873 K下熱處理后，其屈服強(qiáng)度和線彈性極限值均小于鑄態(tài)合金的相應(yīng)值。試樣在873 K下熱處理后，當(dāng)壓縮應(yīng)變達(dá)到18%時，其外表面無任何宏觀裂縫，材料呈現(xiàn)加工硬化現(xiàn)象；而在其余溫度下熱處理后，材料斷裂機(jī)制為延性斷裂與解理斷裂相混合的斷裂機(jī)制。
關(guān)鍵字: Zr-Co合金；B33相；熱處理溫度；力學(xué)性能
（School of Materials and Engineering, Shaanxi University of Technology, Hanzhong 723000, China）
Abstract:The microstructure and mechanical properties of Zr44Co56 alloy were studied by X-ray diffraction (XRD), metallographic microscopy, universal testing machine and scanning electron microscopy (SEM). The results show that the microstructures of the specimens at different heat-treatment temperatures are composed of B2 matrix phase and the second phase B33 phase. At heat-treatment temperatures of 723, 773 and 823 K, the relative content of the B33 phases exhibits an increasing trend comparing with the as-cast alloy. At 873 K, a small amount of the B33 phases precipitate at the grain boundaries; the particle shapes transform from the small bulk of as-casting state to thick line strip, and then to thin strips with increasing the heat-treatment temperature. The yield strength and elastic limit values of samples at the heat-treatment temperature of 723 K are greater than those of the as-cast alloy; however, the yield strength and elastic limit values of samples at heat-treatment temperatures of 773, 823 and 873 K are less than those of the as-cast alloy. When the compressive strain reaches 18%, the outer surface of the sample at the heat-treatment temperature of 873 K has no macroscopic cracks, and the material exhibits the work-hardening phenomenon; and the fracture mechanism of samples is the combining fracture mechanism of ductile fracture and cleavage fracture at other heat-treatment temperatures.
Key words: Zr-Co alloy; B33 phase; heat treatment temperature; mechanical property
