Al_5TiB对消失模铸造B319铝合金组织性能的影响

Effect of Al_5TiB on the Structure and Propertiesof B319 Aluminum Alloy in Lost Foam Casting

利用等离子体发射光谱仪、X射线衍射仪、差分扫描量热仪以及金相分析等手段 ,研究了Al5Ti B中间合金对消失模铸造 B31 9铝合金组织性能的影响 .结果表明 ,Al5Ti B不改变消失模铸造 B31 9铝合金 β- Fe相及 Al2 Cu相的析出机理 ,但会使 β- Fe相粗化 ,并减少 β- Fe相数量 ;Al5Ti B改变了金属型铸造 B31 9铝合金 Fe相的析出形态 ,Fe相以针状 β- Fe形式析出 ,而不再以文字状的α- Fe形式析出 .研究发现 ,消失模铸造 B31 9铝合金的共晶温度和 Al2 Cu相析出温度均比金属型铸造条件下的要高 ;采用 Al5Ti B加入 0 .1 5 % Ti,消失模铸造 B31 9铝合金的共晶温度和 Al2 Cu相析出温度分别为 5 69.8°C和 5 1 3.3°C,而在金属型铸造条件下 ,则分别降为 5 64.7°C和 5 1 0 .6°C.Al5Ti B可使消失模铸造 B31 9铝合金平均晶粒尺寸从 80 0 μm降至 370 μm以下 ;合金的 σb 和 δ分别从 1 5 2 MPa和 1 .6%提高到 1 67MPa和 2 .1 %以上 .

By use of ICP spectroscopy, X-ray diffraction, the differential scanning calorimetric (DSC) and microscope analysis, the effects of Al5TiB master alloy on the structure of B319 aluminum alloy in lost foam casting are studied. The results show that the precipitation mechanism of β-Fe and Al2Cu phases do not change by Al5TiB. But with the addition of Al5TiB, β-Fe phases become thicker and its number decreases under lost foam casting slow cooling rate. The Chinese script α-Fe phases will transform to the needle-like β-Fe phases under the rapid cooling rate condition in metallic mold by Al5TiB. The research results also show that the eutectic temperature and Al2Cu precipitation temperature in lost foam casting are higher than that in metallic mold. With the addition of 0.15%Ti by Al5TiB, the eutectic temperature and Al2Cu precipitation temperature in lost foam casting are 569.8°C and 513.3°C, respectively. But the eutectic temperature and Al2Cu precipitation temperature in metallic mold decrease to 564.7°C and 510.6°C, respectively. The grain sizes of α-Al can decrease from 800 μm to below 370μm by Al5TiB, and σb and δ increase from 152 MPa and 1.6% to above 167 MPa and 2.1%, respectively.