(1. 蘭州理工大學(xué) 甘肅省有色金屬新材料省部共建國(guó)家重點(diǎn)實(shí)驗(yàn)室，蘭州 730050；2. 蘭州理工大學(xué) 有色金屬合金及加工教育部重點(diǎn)實(shí)驗(yàn)室，蘭州 730050)
摘 要: 采用等溫?zé)崽幚韺?duì)AZ91D鎂合金進(jìn)行非枝晶化，研究半固態(tài)鎂合金的觸變壓鑄工藝，得到性能良好的觸變壓鑄鎂合金試件。通過改變壓力和壓射速度等工藝參數(shù)，發(fā)現(xiàn)其抗拉強(qiáng)度和伸長(zhǎng)率都隨著壓力或速度的上升而增加，當(dāng)增壓壓力為35 MPa和壓射速度為4.5 m/s時(shí)，其抗拉強(qiáng)度達(dá)到最大，為237.5 MPa，伸長(zhǎng)率為4.8%。通過組織分析認(rèn)為，半固態(tài)觸變壓鑄對(duì)晶粒細(xì)化效果明顯，這與固相顆粒在充型過程中的二次破碎，液相噴射分散后凝固具有直接的關(guān)系。
關(guān)鍵字: 鎂合金；觸變成形；半固態(tài)壓鑄；等溫處理；力學(xué)性能
（1. State Key Laboratory of Gansu Advanced Non-ferrous Metal Materials, Lanzhou University of Technology, Lanzhou 730050, China;2. Key Laboratory of Non-ferrous Metal Alloys and Processing, Ministry of Education, Lanzhou University of Technology, Lanzhou 730050, China）
Abstract:The non-dendrite or spherical grains microstructure of AZ91D magnesium was obtained using the isothermal treatment technique and the thixo-casting process were studied under semi-solid state. The specimens with good properties were obtained and analyzed. The effects of injection speed and additional pressure on tensile strength, elongation rate and microstructure of specimens were investigated. The results show that the mechanical properties of alloy can be improved with the increase of injection speed and additional pressure. While the additional pressure is 35 MPa and the injection speed is 4.5 m/s, the tensile strength and elongation rate can reach 237.5 MPa and 4.8%, respectively. Through the microstructure analysis, the semi-solid thixo-casting most obviously refines the crystal grain. The solid phase particles in the semi-solid ingot may be broken into pieces again and the liquid phase may be sprayed and solidified during filling process due to most high shearing strength.
Key words: magnesium alloy; thixo-forming; semi-solid die casting; isothermal heat treatment; mechanical properties
