1. 晶(jing)粒(li)（crystalline grain）、晶(jing)界（grain boundary）
組成(cheng)金屬材(cai)料的(de)小晶(jing)(jing)體，稱為晶(jing)(jing)粒(li)。晶(jing)(jing)粒(li)與晶(jing)(jing)粒(li)之間的(de)分界面(mian)，稱為晶(jing)(jing)界。
2. 相（phase）、相界（phase boundary）
在金(jin)屬或合金(jin)中，凡成分(fen)相同、結(jie)構相同并有界面互(hu)相隔開的均勻組成部分(fen)，稱為相，相與相之(zhi)間的界面，稱為相界。
3. 固溶體(ti)（solid solution）
組成合金的(de)(de)一種(zhong)金屬元素的(de)(de)晶體(ti)中溶(rong)(rong)有另一種(zhong)元素的(de)(de)原子形成的(de)(de)固(gu)態相(xiang)，稱(cheng)為固(gu)溶(rong)(rong)體(ti)。固(gu)溶(rong)(rong)體(ti)一般有較高的(de)(de)強(qiang)度、良好的(de)(de)塑(su)性、耐(nai)蝕性以及高的(de)(de)電阻和磁性。
按(an)溶(rong)質原(yuan)子在晶(jing)格中(zhong)的(de)位(wei)置不同可分為置換固溶(rong)體和(he)間(jian)隙固溶(rong)體。
①. 置(zhi)(zhi)換(huan)(huan)固溶(rong)(rong)(rong)體：溶(rong)(rong)(rong)質(zhi)原子占據(ju)溶(rong)(rong)(rong)劑(ji)晶格中的(de)(de)結點位(wei)置(zhi)(zhi)而形成(cheng)的(de)(de)固溶(rong)(rong)(rong)體稱置(zhi)(zhi)換(huan)(huan)固溶(rong)(rong)(rong)體。當溶(rong)(rong)(rong)劑(ji)和溶(rong)(rong)(rong)質(zhi)原子直徑相差不大，一般(ban)在(zai)15％以(yi)內時，易于形成(cheng)置(zhi)(zhi)換(huan)(huan)固溶(rong)(rong)(rong)體。銅鎳二元合金即形成(cheng)置(zhi)(zhi)換(huan)(huan)固溶(rong)(rong)(rong)體，鎳原子可在(zai)銅晶格的(de)(de)任意位(wei)置(zhi)(zhi)替代銅原子。
②. 間(jian)(jian)隙(xi)固(gu)(gu)(gu)溶(rong)(rong)(rong)體(ti)(ti)(ti)(ti)：溶(rong)(rong)(rong)質原(yuan)子(zi)分布于溶(rong)(rong)(rong)劑晶(jing)格(ge)間(jian)(jian)隙(xi)而形(xing)成的(de)(de)固(gu)(gu)(gu)溶(rong)(rong)(rong)體(ti)(ti)(ti)(ti)稱間(jian)(jian)隙(xi)固(gu)(gu)(gu)溶(rong)(rong)(rong)體(ti)(ti)(ti)(ti)。間(jian)(jian)隙(xi)固(gu)(gu)(gu)溶(rong)(rong)(rong)體(ti)(ti)(ti)(ti)的(de)(de)溶(rong)(rong)(rong)劑是(shi)直徑較(jiao)大的(de)(de)過渡族(zu)金(jin)屬(shu)，而溶(rong)(rong)(rong)質是(shi)直徑很小的(de)(de)碳(tan)(tan)、氫等(deng)非金(jin)屬(shu)元素。其形(xing)成條件是(shi)溶(rong)(rong)(rong)質原(yuan)子(zi)與溶(rong)(rong)(rong)劑原(yuan)子(zi)直徑之比必須小于0.59。如(ru)鐵(tie)(tie)碳(tan)(tan)合金(jin)中，鐵(tie)(tie)和(he)碳(tan)(tan)所形(xing)成的(de)(de)固(gu)(gu)(gu)溶(rong)(rong)(rong)體(ti)(ti)(ti)(ti)-鐵(tie)(tie)素體(ti)(ti)(ti)(ti)和(he)奧氏(shi)體(ti)(ti)(ti)(ti)，皆為間(jian)(jian)隙(xi)固(gu)(gu)(gu)溶(rong)(rong)(rong)體(ti)(ti)(ti)(ti)。
按固(gu)溶(rong)(rong)度來分類，可(ke)分為有限(xian)固(gu)溶(rong)(rong)體(ti)和(he)無(wu)限(xian)固(gu)溶(rong)(rong)體(ti)。無(wu)限(xian)固(gu)溶(rong)(rong)體(ti)只可(ke)能是(shi)置換(huan)固(gu)溶(rong)(rong)體(ti)。
按(an)溶(rong)質(zhi)原子與溶(rong)劑原子的(de)相對分布來分，可(ke)分為(wei)無序固溶(rong)體(ti)和有(you)序固溶(rong)體(ti)。
4. 金屬化(hua)合物（metal compounds）
合(he)金(jin)(jin)中不(bu)同(tong)元素的原子相互作用形成(cheng)的、晶格類型和性(xing)能都完全(quan)不(bu)同(tong)于其組成(cheng)元素的，具有金(jin)(jin)屬特(te)性(xing)的固態相，稱為金(jin)(jin)屬化(hua)合(he)物。金(jin)(jin)屬化(hua)合(he)物多數具有熔點(dian)高、硬(ying)而脆(cui)的特(te)點(dian)，是合(he)金(jin)(jin)中很重要的強(qiang)化(hua)相。
