工艺参数对触变压铸Al-30Si组织和性能的影响

研究了等温处理工艺和压射速度对触变压铸Al-30Si合金(加入1%的磷盐变质处理)组织和力学性能的影响。结果表明,触变压铸组织和常规铸锭组织相比,初生Si的形貌更加圆整,针状的共晶Si消失,而α-Al的的枝晶被打碎,以弥散的颗粒状分布;在固相率较高时,部分α-Al未熔化,以固相保留下来,形态为球状或近球状。常温下的抗拉强度在620℃保温100min和120min时,都随压射速度的增加呈现出先增大后减小的趋势,前者的最大值出现在6m/s,为226MPa;而后者的最大值出现在4m/s,为230MPa。在630℃保温120min时,抗拉强度随压射速度的增加而逐渐减小。

Effects of Processing Parameters on Microstructure and Mechanical Properties of Thixo-forming Al-30Si Alloy

Effects of isothermal treatment process and injection speed on microstructure and mechanical properties of thixo-forming Al-30Si alloy with 1% P modification were investigated by SEM(scanning electron microscope),XRD(X-ray diffraction) and tensile testing.The results show that the morphology of primary Si phase exhibits more spherical with disappearance of acicular eutectic Si phase compared with as-cast microstructure,while α-Al phase is dispersedly distributed in the matrix as a result of broking into.A part of α-Al phase is retained in the slurry with the higher solid fraction.Ambient tensile strength of the alloy with holding at 620℃ for 100 min and 120 min firstly increases and then decreases with increasing in injection velocity,while for the 100 min,the maximum value of tensile strength is 226MPa at 6 m/s,and for 120 min,it is 230 MPa at 4 m/s.However,with holding at 630℃ for 120 min,tensile strength of the alloy is gradually decreased with the increase of the injection velocity.