(1. 合肥工業(yè)大學 材料科學與工程學院，合肥 230009；
2. Chemical Sciences and Materials Systems Laboratory,
General Motors Research and Development Center, Warren, MI 48090-9055, USA)
摘 要: 利用壓鑄工藝將液態(tài)鎂和固態(tài)鋁液-固復合是一種鎂/鋁異種材料焊接的新工藝。鎂/鋁異種活性金屬液-固連接的難點首先是固態(tài)鋁合金屬表面存在一層氧化膜，阻礙鎂/鋁異種活性金屬之間形成冶金結合，其次是鎂/鋁液固復合過程中無法避免地形成大量的金屬間化合物，這些脆性相極大地破壞了界面的力學性能。對鋁合金表面進行氧化膜去除工藝，并在此基礎上，利用自制的液固雙金屬復合裝置將液態(tài)鎂鑭中間合金與經(jīng)過表面處理的固態(tài)鋁合金進行液固復合。研究鎂合金中的稀土La對鎂鋁液固擴散連接界面組織及性能的影響。結果表明：鎂合金中加入稀土La后，鎂鋁擴散連接界面處的β-Mg17Al12變少、變細，鑄態(tài)晶粒細化；大部分La與Al結合生成高熔點、高熱穩(wěn)定性的稀土相Al11La3相；當鎂合金中含有1%(質量分數(shù))稀土La時，界面可達到最大的抗剪強度88.5MPa。
關鍵字: 鋁合金；氧化膜；鎂/鋁復合；La；界面組織
（1. School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009, China;
2. Chemical Sciences and Materials Systems Laboratory,
General Motors Research and Development Center, Warren, MI 48090-9055, USA）
Abstract:Die-casting is a new magnesium/aluminum dissimilar welding process via casting liquid Mg alloy onto the solid Al alloy substrate. The difficulty of liquid-solid connection of magnesium/aluminum is the nature oxide layer on the solid Al alloy substrate surface that usually prevents metallurgical bonding between the magnesium and aluminum. During this process, the formation of some intermetallic compounds with a high hardness and brittleness over the interface would deteriorate the mechanical property of materials. The process of removing the oxide layer on solid Al substrate surface was investigated, and on this basis, the melt magnesium alloy was cast onto the solid aluminum alloy A390 by using home-made liquid-solid bimetal composite device. The effect of La on the structures and properties of the liquid-solid diffusion bonding interface of Mg/Al was researched. The results indicate that after adding the rare earth La into the magnesium alloys, β-Mg17Al12 at the interface of magnesium aluminum diffusion bonding gradually becomes less and thinner, and the cast grain is gradually refined. Most of La and Al combine to generate high melting point and high heat stability of rare earth phase-Al11La3 phase. When the magnesium alloys contain 1% rare earth La, the maximal shearing strength of the interface can achieve 88.5 MPa.
Key words: aluminum alloy; oxide layer; Mg/Al compound; La; interface structure
