Microstructures and mechanical properties of BP/7A04 Al matrix composites

The microstructures and interface structures of basalt particle reinforced 7A04 Al matrix composites (BP/7A04 Al) were analyzed by using OM, TEM, SEM and EDS, and the mechanical properties of 7A04 Al alloy were compared with those of BP/7A04 Al matrix composites. The results show that the basalt particles are dispersed in the Al matrix and form a strong bonding interface with the Al matrix. SiO2 at the edge of the basalt particles is continuously replaced by Al2O3 formed in the reaction, forming a high-temperature reaction layer with a thickness of several tens of nanometers, and Al2O3 strengthens the bonding interface between basalt particles and Al matrix. The dispersed basalt particles promote the dislocation multiplication, vacancy formation and precipitation of the matrix, and the precipitated phases mainly consist of plate-like η(MgZn2) phase and bright white band-shaped or ellipsoidal T (Al2Mg3Zn3) phase. The bonding interface, high dislocation density and dispersion strengthening phase significantly improve the mechanical properties of the composites. The yield strength and ultimate tensile strength of BP/7A04 Al matrix composites are up to 665 and 699 MPa, which increase by 11.4% and 10.9% respectively compared with 7A04 Al alloy without basalt particles.

Phase equilibria of Zn-Al-Ti ternary system at 450 and 600℃

The phase relationships in the Zn-Al-Ti system at 450 and 600℃ were experimentally determined using equilibrated alloys method.The specimens were investigated by means of scanning electron microscopy coupled with energy dispersive spectroscopy and X-ray diffractometry.Eleven and eight three-phase regions are confirmed in the 450 and 600℃ isothermal sections,respectively.The Ti2Al5 which only exists at high temperature(990-1199.4℃)in Ti-Al binary system is confirmed in two isothermal sections due to the dissolution of zinc.The T phase is confirmed as a ternary compound rather than an extension phase of TiZn3 at 450℃.The T2 phase is a new ternary phase stable at 450 and 600℃ in Zn-Al-Ti ternary system.

Microstructure and mechanical properties of Al-Si alloy modified with Al-3P

Al-Si alloy was modified with Al-3P master alloy at 740℃.The effects of Si content(7,8,9,10 and 11 wt.%) and adding amount of alterant A1-3P(0,0.1,0.3,0.6,1.0 and 1.5 wt.%) on microstructures and tensile properties of the alloy were investigated with optical microscope(OP),Image Pro Plus 6.0,scanning electron microscope(SEM) and universal testing machine.When the content of Al-3P is 0.6 wt.%,the area fraction of primary a(Al) in the Al-Si alloy increases more compared to the unmodified alloy with an increase in Si content,which could be explained by the movement of non-equilibrium eutectic point.When the Si content is constant(Al-lOSi),with the increase of Al-3P content,the increased rate in area fraction of primary a(Al) phase in the Al-lOSi alloy increases first and then decreases.And when 0.6 wt.% Al-3P is added,the increase in area fraction of primary a(Al) phase is the largest.Compared to the unmodified Al-lOSi alloy,the tensile strength and elongation of Al-lOSi alloy increase by 2.3% and 47.0%,respectively,after being modified with 0.6 wt.% Al-3P alloy.The fracture mode of the modified Al-lOSi alloy is ductile fracture.

7050铝合金应力腐蚀敏感性和钝化膜引起的膜致应力随电位变化的一致性（英文）

用流变应力差值法测量了不同极化电位下7050铝合金在3.5%NaCl水溶液(pH=10)腐蚀过程中表面钝化膜形成的拉应力,并用慢应变速率拉伸法测量了不同极化电位下的应力腐蚀敏感性。结果表明:7050铝合金在溶液中自然腐蚀时,表面钝化膜会产生一定的拉应力;阳极极化使表层拉应力明显上升,且随着电位升高应力增大;阴极极化时,当电位E≥-1100 mV时表层拉应力随着电位的升高而降低,当电位E≤–1100 mV时拉应力随着电位升高而升高。应力腐蚀敏感性随外加电位变化规律和钝化膜引起的附加拉应力变化完全一致。